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  • 1980-1984  (643)
  • 1920-1924
  • 1982  (643)
  • Physics  (517)
  • Physical Chemistry  (126)
  • 1
    Digitale Medien
    Digitale Medien
    The mechanism of O3-aldehyde reactions (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 237-249 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new mechanism is proposed for gas-phase O3-aldehyde reactions. Certain aspects of the new mechanism may be applicable also to O3-aldehyde reactions in solution. The proposed mechanism involves initiation by addition of O3 across the aldehydic C=O bond. The initiation process and the subsequent chemistry together represent an exact analogue of the Criegee mechanism for O3-alkene reactions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140304
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  • 2
    Digitale Medien
    Digitale Medien
    Kinetics and energetics of the criegee intermediate in the gas phase. II. The criegee intermediate in the photooxidation of formaldehyde, in alkyldioxy disproportionation and O + oxoalkane addition reactions (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 225-236 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas-phase kinetics and energetics of the Criegee intermediate, deduced from studies of O3-alkene systems, suggest that a hydroxy-substituted Criegee intermediate probably participates in the photooxidation of formaldehyde. In contradistinction, the existing evidence suggests that the Criegee intermediate and its isomers are probably not involved in alkyldioxy disproportionation reactions. In the case of O + oxoalkane addition reactions, the Criegee intermediate and its isomers are discussed in terms of a complex equilibrium: .
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140303
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  • 3
    Digitale Medien
    Digitale Medien
    Kinetics of the thermal reactions of bicyclo[4.2.2]deca-3,7-diene and endo-and exo-5-vinylbicyclo[2.2.2]oct-2-ene in the gas phase (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 251-257 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the thermal reactions of bicyclo[4.2.2]deca-3,7-diene (BDD) and endo- and exo-5-vinylbicyclo[2.2.2]oct-2-ene (endo- and exo-VBO) have been studied in the gas phase. The temperature range was 459-526 K for BDD, 476-563 K for endo-VBO, and 513-578 K for exo-VBO. The initial pressures were varied from 2 to about 40 torr. These compounds isomerize to cis-1,2,4a,5,8,8a-hexahydronaphtalene (HHN) and into each other, and decompose to 1,3-butadiene (BD) + cyclohexa-1,3-diene (CHD). The reactions are homogeneous and first order. Their rate constants (in s-1) are given by: where the superscripts represent the reagents and the subscripts the products. The heats of formation and the entropies of endo-VBO, exo-VBO, and BDD are estimated.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140305
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  • 4
    Digitale Medien
    Digitale Medien
    Heterogeneous reactions of sulfur dioxide with carbonaceous particles (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 269-277 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate of adsorption of SO2 on a prototype carbonaceous surface was measured at low pressure in a flow reactor. The measured rate indicates a maximum atmospheric loss of SO2 by heterogeneous reaction of 1%/h for a particle density of 100 μg/m3. The capacity of carbon particles to adsorb SO2 is limited at ∼1 mg SO2 g-1 C. NO2 has no effect on the rate of SO2 adsorption or the saturation behavior.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140307
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  • 5
    Digitale Medien
    Digitale Medien
    Kinetics and mechanism of the addition of 1,3-butadiene to cyclohexa-1,3-diene in the gas phase (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 259-267 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermal reactions of 1,3-butadiene (BD) with cyclohexa-1,3-diene (CHD) have been studied in a static system between 437 and 526 K. The pressures of BD and CHD were varied from 61 to 397 torr and from 50 to 93 torr, respectively. The percentages of consumed BD and CHD were always kept lower than 14%. The reactions - in the order of importance - are All the reactions are homogeneous and of the first order with respect to the reagents. Their rate constants (in L/mol·s) are given by \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \log _{10} k_{{\rm HHN}} = - (25,370 \pm 70)/4.576T + (7.02 \pm 0.03) \\ \log _{10} k_{{\rm KNDO}} = - (24,840 \pm 50)/4.576T + (6.58 \pm 0.02) \\ \log _{10} k_{{\rm BDD}} = - (25,530 \pm 50)/4.576T + (6.61 \pm 0.02) \\ \log _{10} k_{{\rm EXO}} = - (26,760 \pm 50)/4.576T + (7.06 \pm 0.02) \\ \end{array} $$\end{document} A thermochemical analysis of a biradical mechanism is in agreement with these results.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140306
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  • 6
    Digitale Medien
    Digitale Medien
    Shock-initiated decomposition of tetramethylgermane and the reaction of methyl radicals with toluene (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 279-289 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The shock-initiated decomposition of tetramethylgermane (1078-1242 K) has been found to involve successive elimination of methyl radicals with the rate constant k1 for the first step given by \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_{\rm 1} {\rm}(s^{- 1}) = {\rm}(17.00 \pm 0.35) - (77.0 \pm 1.9)\theta {\rm kcal/mol} $$\end{document} In the presence of excess toluene the products were CH4 (major), C2H4, and C2H6. Results relevant to the reaction of methyl radicals with toluene compared to methyl radical recombination are discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140308
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  • 7
    Digitale Medien
    Digitale Medien
    Masthead (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982) 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140401
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  • 8
    Digitale Medien
    Digitale Medien
    The thermal decomposition of fluorinated esters. II. The effect of γ-substitution (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 291-297 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas-phase kinetics of thermal decomposition of ethyl difluoroacetate, pentafluoropropionate, and hepatfluorobutyrate have been studied. The normal ester decomposition route to ethylene plus carboxylic acid is taken in each case, but the fluorinated acids decompose rapidly at the temperatures used. The primary decompositions are homogeneous and unimolecular, and the three Arrhenius equations are \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \log k{\rm}({\rm CF}_2 {\rm HCO}_2 {\rm Et}){\rm}({\rm s}^{- 1}) = (12.81 \pm 0.39) - (46,740 \pm 1290){\rm cal/mol/2}{\rm .303}RT \\ \log k{\rm}({\rm C}_2 {\rm F}_5 {\rm CO}_{\rm 2} {\rm Et}){\rm}({\rm s}^{- 1}) = (12.16 \pm 0.32) - (43,760 \pm 970){\rm cal/mol/2}{\rm .303}RT \\ \log k{\rm}({\rm C}_3 {\rm F}_7 {\rm CO}_{\rm 2} {\rm Et}){\rm}({\rm s}^{- 1}) = (12.29 \pm 0.13) - (43,880 \pm 370){\rm cal/mol/2}{\rm .303}RT \\ \end{array} $$\end{document} The postulate of a slightly electron-rich γ carbon in six-center ester transition states is supported by the higher rates and lowered activation energies observed when increasingly electron-withdrawing fluorinated groups are linked to this center. The stabilization is reflected in a ρ constant of +0.30. The results are compared with previous work on α substitution in fluorinated esters.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140309
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  • 9
    Digitale Medien
    Digitale Medien
    Specialist periodical reports. Gas kinetics and energy transfer, volume 4, edited by P. G. Ashmore and R. J. Donovan, The Royal Society of Chemistry, London, 1981. Pp. VI + 242 (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 325-326 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140311
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  • 10
    Digitale Medien
    Digitale Medien
    The kinetics and mechanisms of the gas-phase unimolecular eliminations of halogeno esters. Participation of the carbomethoxy group (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 381-397 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the gas-phase elimination of several chloroesters were determined in a static system over the temperature range of 410-490°C and the pressure range of 47-236 torr. The reactions in seasoned vessels, and in the presence of a free-radical inhibitor, are homogeneous, unimolecular, and follow a first-order law. The temperature dependence of the rate coefficients is given by the following Arrhenius equations: for methyl 3-chloropropionate, log k1(s-1) = (13.22 ± 0.07) - (231.5 ± 1.0) kJ/mol/2.303RT; for methyl 4-chlorobutyrate, log k1(s-1) = (13.31 ± 0.25) - (221.5 ± 3.4) kJ/mol/2.303RT; and for methyl 5-chlorovalerate, log k1(s-1) = (13.12 ± 0.25) - (221.7 ± 3.2) kJ/mol/2.303RT. Rate enhancements and lactone formation reveal the participation of carbonyl oxygen of the carbomethoxy group. The order COOCH3-5 〉 COOCH3-6 〉 COOCH3-4 in assistance is similar to the sequence of group participation in solvolysis reactions. The partial rates for the parallel eliminations to normal dehydrohalogenation products and lactones have been estimated and reported. The present results lead us to consider that an intimate ion-pair mechanism through participation of the carbomethoxy group may well be operating in some of these reactions.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140406
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  • 11
    Digitale Medien
    Digitale Medien
    Cyclobutane production via the O3--thiolane reaction (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 439-445 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140410
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  • 12
    Digitale Medien
    Digitale Medien
    An empirical formula for gas-wall collision efficiencies in VLPP experiments (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 447-450 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140411
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  • 13
    Digitale Medien
    Digitale Medien
    A dual-frequency Belousov Zhabotinskii oscillating reaction with ethyl acetoacetate as organic substrate (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 815-821 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The experimental behavior of the cerium- and manganese-catalyzed Belousov Zhabotinskii oscillating reaction with ethyl acetoacetate as organic substrate has been investigated. Under certain conditions the system displays two types of temporal oscillations. Damped highfrequency oscillations appear immediately after the addition of potassium bromate solution to complete the reaction mixture. These high-frequency oscillations may be regarded as being superimposed on an induction period of the type found in the reaction using malonic acid. After the induction period, low-frequency oscillations of the normal type are obtained. Both the high-frequency and the low-frequency oscillations can be monitored with a platinum redox or with a bromide specific ion electrode.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140802
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  • 14
    Digitale Medien
    Digitale Medien
    Rate constants for the gas-phase reaction of OH radicals with a series of ketones at 299 ± 2 K (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 839-847 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Relative rate constants for the reaction of OH radicals with a series of ketones have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of hydroxyl radicals. Using a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10-12 cm3 molecule-1 s-1, the rate constants obtained are (× 1012 cm3 molecule-1 s-1): 2-pentanone, 4.74 ± 0.14; 3-pentanone, 1.85 ± 0.34; 2-hexanone, 9.16 ± 0.61; 3-hexanone, 6.96 ± 0.29; 2,4-dimethyl-3-pentanone, 5.43 ± 0.41; 4-methyl-2-pentanone, 14.5 ± 0.7; and 2,6-dimethyl-4-heptanone, 27.7 ± 1.5. These rate constants indicate that while the carbonyl group decreases the reactivity of C—H bonds in the α position toward reaction with the OH radical, it enhances the reactivity in the β position.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140804
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  • 15
    Digitale Medien
    Digitale Medien
    The reaction of methyl p-nitrophenyl sulfate with hydrogen peroxide anion determination of pKa of hydrogen peroxide in methanol by a kinetic spectrophotometric procedure (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 823-837 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A kinetic spectrophotometric investigation of the reaction of the hydrogen peroxide anion with methyl p-nitrophenyl sulfate in methanol solvent resulted in the evaluation of the pKa of HOOH in methanol at 25°C as 15.8 ± 0.2. Since normal kinetic procedures for the determination of the equilibrium constant K for the process CH3O- + H2O2 ⇄ CH3OH + HO2- were found to be associated with high uncertainty, another procedure was devised to establish the magnitude of K. This method is based on an analysis of the changing slopes of plots of pseudo-first-order rate constants against the total base concentration as the stoichiometric amount of hydrogen peroxide is varied. The method is applicable to any system in which anionic nucleophiles generated in situ compete with solvent anions. Such a corroboration of kinetically determined equilibrium constants is believed essential. The kinetic data allow the specific rate constant kHOO-for the reaction of methyl p-nitrophenyl sulfate with hydrogen peroxide anions to be evaluated and yield the rate constant ratio kHOO-/kMeO- = 8.8 ± 2.2. This confirms the existence of an α effect at saturated carbon in this system.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140803
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  • 16
    Digitale Medien
    Digitale Medien
    A reexamination of the pyrolysis of bis trifluoromethyl peroxide (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 933-944 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The literature results for the pyrolysis of bis trifluoromethyl peroxide are reexamined and compared with those for dimethyl peroxide. The thermochemistry yields the result that the π-bond energy in carbonyl fluoride is 96 ± 10 kcal/mol compared to 74 kcal/mol for that in formaldehyde. Thermodynamic additivity contributions are derived for the C—(F)3(O) and O—(C)(F) groups. Some conclusions are drawn in relation to the oxidation of halogeno methyl radicals and the chemistry of the atmosphere.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550140812
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  • 17
    Digitale Medien
    Digitale Medien
    Reaction of hot H atoms with CDCl3 (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 1105-1112 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Energetic hydrogen atoms generated by photolysis of HBr or HI react with CDCl3 by abstracting either a deuterium atom (1) or a chlorine atom (2): The integral probability of reaction (2) has been measured for several defined initial translational energies of H*, and the phenomenological threshold energy is 31 ± 14 kJ/mol. For initial translational energies in the range of 66-121 kJ/mol, the ratio of the integral probabilities of Cl abstraction and of D abstraction, when normalized to equal numbers of Cl and D atoms, is 2.4 ± 0.3. The interpretation of the integral reaction probabilities in terms of the excitation functions of reactions (1) and (2) is discussed. Measurements of the moderating effect of CO2 on reactions (1) and (2) show that CDCl3 is slightly more effective than CO2 as a moderator of H atoms in the energy range of 90-30 kJ/mol.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550141004
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  • 18
    Digitale Medien
    Digitale Medien
    Kinetics and mechanism of the oxidation of halotoluenes by acidic hexacyanoferrate(III) (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 1113-1124 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The oxidation of halotoluenes by hexacyanoferrate(III) in aqueous acetic acid containing perchloric acid (0.5M) at 50°C gave the corresponding aldehyde as the major product, and a small amount of polymeric material. The order with respect to each of the reactants - substrate, oxidant, and acid - was found to be unity. Increasing proportions of acetic acid increased the rate of the reaction. The reaction was influenced by changes in temperature, and the activation parameters have been evaluated. The Hammett plot yielded a ρ+ value of -1.8. A kinetic isotope effect kH/kD = 6.0 has been observed. The pathway for the conversion of the halotoluenes to the products has been mechanistically visualized as proceeding through the benzylic radical intermediate, formed in the rate-determining step of the reaction. The radical undergoes rapid conversion to the products.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550141005
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  • 19
    Digitale Medien
    Digitale Medien
    Masthead (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982) 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550141101
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  • 20
    Digitale Medien
    Digitale Medien
    Spectra of propylperoxy radicals and rate constants for mutual interaction (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 1125-1138 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The flash photolyses of azo-n-propane and azoisopropane in the presence of oxygen have been studied by kinetic spectroscopy. The transient absorption spectra observed in the region of 210-290 nm are assigned to the n-propylperoxy and isopropylperoxy radicals. For the n-propylperoxy radical, εmax = 1148 ± 29 L/mol cm at 242.5 nm and for the isopropylperoxy radical, εmax = 1273 ± 75 L/mol cm at 240 nm. The rate constants for the mutual reactions (7) 2RO2· → products were measured to be k7 = (2.0 ± 0.2) X 108 L/mol s for the n-propylperoxy radical and k7 = (7.8 ± 2.2) X 105 L/mol s for the isopropylperoxy radical.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550141006
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  • 21
    Digitale Medien
    Digitale Medien
    Mechanism of oxidation of diphenyl sulfide by peroxyanions (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 1139-1147 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reactions of diphenyl sulfide with the two oxidants peroxydisulfate and peroxydiphosphate are described. With each oxidant, the reaction is first order in the oxidant and zero order in the substrate. The rate of the reaction is also independent of the effect of the substituent. Hydrogen ion catalyzes the reactions. The lack of inhibition of the reaction rate by added acrylamide rules out the possibility of a radical reaction initiated by the homolysis of the peroxyanions. From the effect of [H+] on the oxidation rates, the active species involved in the reactions have been determined. The redox reaction is essentially proceeding via hydrolysis of the protonated peroxy anions in a rate-determining step, followed by a fast step involving the oxidation of diphenyl sulfide to diphenyl sulfoxide. This has been confirmed by estimating the hydrolyzed products in each case and also by the product analyses.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550141007
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  • 22
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    Digitale Medien
    A flash photolysis resonance fluorescence investigation of the reaction OH + H2O2 → HO2 + H2O (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 14 (1982), S. 1149-1161 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The flash photolysis resonance fluorescence technique has been used to measure the rate constant for the reaction over the temperature range of 250-370 K. The present results are in excellent agreement with three very recent studies, and the combined data set can been used to derive the expression similar to that currently used in atmospheric modeling applications.A summary of our computer simulation of this reaction system is presented. The results of the computations indicate the absence of secondary reaction complications in the present work while revealing significant problems in the earlier (pre-1980) studies of the title reaction.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550141008
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  • 23
    Digitale Medien
    Digitale Medien
    Effect of disorder in the twist angle on light scattering by a three-dimensional spherulite (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1-13 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Light scattering patterns are calculated for imperfect three-dimensional spherulites with fluctuations in the twist angle. The fluctuations are described in terms of a parameter characterizing the distance correlation function. Cases are considered in which (i) the principal axis of the scattering element makes a constant angle with the radius but there is disorder in the twist angle about the axis, and (ii) there is combined twist disorder and orientation disorder of the scattering elements. Calculations suggest that the disorder in the twist angle may lead to a decrease in the higher-order variation of scattered intensity with scattering angle and deviation from the four-leaf-clover-type scattering characteristic of a perfect spherulite at lower scattering angles. On the other hand, disorder in orientation has little effect on the scattering pattern.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200101
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  • 24
    Digitale Medien
    Digitale Medien
    Effect of glass filler size on the tensile properties and tear strength of polybutadiene (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 49-63 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: An experimental study of the tensile properties, tear strength, hysteresis, and swelling ratio of model composite elastomeric compounds consisting of polybutadiene filled with glass beads has been carried out as a function of the size of the beads. The diameter of the beads ranged from 25 to 1000 μm and the volume fractions examined were 0.16, 0.092, and 0.048. Mechanical properties of the filled elastomers were functions of the loading (separation distance), the particle size (surface area/volume), and the elastomer-filler systems studied.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200104
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  • 25
    Digitale Medien
    Digitale Medien
    Concentrated solution viscosities of polymeric associates (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 99-106 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Reasons have been advanced why in some cases concentrated-polymer-solution viscosity measurements are not a suitable method for determining the degree of association of groups attached to polymer chains. These are based on the finite lifetimes of associates compared with the finite lifetimes of the entanglements, which are the major contributors to concentrated-polymer-solution viscosities. The validity of these reasons has been checked in a system where the degree of association of polymer chains can be measured spectroscopically. It was found that the viscosity of these solutions was considerably less than that calculated by the concentrated-solution viscosity equation for solutions of polymers of the average molecular weight expected from the spectroscopically found degree of association.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200108
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  • 26
    Digitale Medien
    Digitale Medien
    Poly(P-phenylene sulfide) hexafluoroarsenate: A novel conducting polymer (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 117-130 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Poly(p-phenylene sulfide) (PPS) is a melt- and solution-processible polymer which on treatment with AsF5 forms a blue-black material with a conductivity of 1-10 Ω-1 cm-1. Thermopower measurements indicate that the resulting polymer is p type, consistent with partial oxidation of the PPS by the AsF5. The rate and extent of this doping process prove to be particularly sensitive to the degree of crystallinity of the starting polymer. There is also evidence of crosslinking of the polymer chains during the reaction with AsF5. The details of both the chemistry and physics of the doping of PPS and several of its derivatives are presented.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200110
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  • 27
    Digitale Medien
    Digitale Medien
    Use of quantum chemistry relations in cationic polymerization: A critical examination (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 131-139 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The temperature dependence of the reactivity ratio r2 (subscript 2 for styrene) is reported for 1-and 2-vinyl naphthalenes, 4-halogeno-1-vinyl naphthalenes, 2- and 3-vinyl phenanthrenes, and o-methylstyrene. The monomers are classified with respect to In (1/r2) and ΔH # and ΔS# (the differences in activation parameters for homopropagation and crosspropagation). It is shown that the reaction is entropically controlled. It appears that there is no correlation between stabilization energy (ΔE)rs and ΔH# and that the correlation with In(1/r2) is only apparent. The origin of this lack of correlation is analyzed and a new index of reactivity is proposed; its correlation with ΔH# is quite satisfying.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200111
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  • 28
    Digitale Medien
    Digitale Medien
    Miscibility of polycaprolactone/chlorinated polyethylene blends (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 191-203 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Blends of polycaprolactone (PCL) with chlorinated polyethylenes (PECls) having chlorine contents of 25, 30, 36, 42, and 48% by weight were prepared and studied by differential scanning calorimetry and small-angle light scattering (SALS). It was found that blends made with PECls containing 30% or more chlorine are completely miscible with PCL (a single glass transition temperature Tg is found) while the PCL/PECl(25) blends are immiscible. PCL crystallizes in the miscible blends at any composition and it has an enthalpy of fusion which decreases only slightly with PECl content. Blends in the PECl composition interval of 0-80% are spherulitic, as shown by SALS, but a rodlike morphology is found at the 85% composition and dispersed crystals are observed at higher compositions. It is suggested that the k parameter of the Gordon-Taylor equation can be taken as a measure of the strength of the specific interaction between PCL and PECl. Low values of k (0.26 and 0.35) are found for PCL/PECl blends but a higher value of k (0.51) has been reported for PCL/poly(vinyl chloride) (PVC) blends, indicating a stronger interaction in the latter mixtures. In agreement with these findings poly(α-methyl-α-n-propyl-β-propiolactone) and poly(valerolactone) are not miscible with PECl, whereas they were previously shown to be miscible with PVC.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200203
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  • 29
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    Digitale Medien
    Comparison between neutron and quasielastic light scattering by polyacrylamide gels (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 225-233 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The authors describe small-angle neutron scattering measurements of the screening length ζ in polyacrylamide-water gels. Although these are inhomogeneous systems, the screening length is clearly observable and is in good numerical agreement with the relation E = 3kT/4πζ3, where E is the longitudinal elastic modulus of the gel obtained from measurements of the intensity of qu-asielastically scattered light. Static light scattering observations reveal a larger-scale (ca. 30 nm) superstructure in the gel.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200205
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  • 30
    Digitale Medien
    Digitale Medien
    Melt rheology of ion-containing polymers. I. Effect of ionic content in a model polyesterionomer (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 259-268 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The effects of copolymerizing small amounts of an ionic moiety (0-7 mol %) into the backbone of a polycondensation polymer have been investigated by a combination of linear viscoelastic, steady-shear, and extensional testing. At a constant viscosity in dilute solution, both the zero-shear-rate viscosity and the maximum relaxation time in the melt increase monotonically with an increase in the ionic character. These effects are present after the data are normalized to remove the increase in the glass transition temperature Tg with increased ionic content. Large-strain, steady-shear flow experiments showed that the viscoelastic memory of the melt is affected by ionic content. An increase in ion content causes a decrease in the effect of strain on the memory function. This effect is not apparent in extensional flow experiments, which indicate that the ionic content does not affect the response if the tests are conducted at a constant temperature above Tg.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200208
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  • 31
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    Digitale Medien
    Studies of tensile failure in oriented polymeric fibers by quantitative fractography (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 297-305 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: For some fibers, such as the nylon monofilaments studied here, quantitative information may be obtained from scanning electron micrographs of fracture surfaces. On these surfaces the segment of the cross section that supports the load at the instant of rupture is seen distinctly, and its area can be measured. Normalizing breaking load by this area provides a breaking stress characteristic of the final supporting segment. “Ultimate” breaking stresses calculated in this way indicate (i) For notched filaments, the ultimate breaking stress is almost constant with notch depth and also with strain rate. (ii) For un-notched filaments, there is an increase of breaking load with strain rate, due in part to the extent of the slow cleavage that precedes failure; however, the ultimate breaking stress increases as rate of strain decreases. These two findings are incompatible with mechanisms of failure based on growth of microcracks by heat- and stress-activated chain breakage. A possible explanation involves rearrangement of microfibrils within the fiber which alters their strength distribution. (iii) The apparent strength reduction on wetting nylon filaments in water is due to a faster rate of growth of the slow-cleavage area; the ultimate breaking stress is unchanged, except at high rates of strain.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200211
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  • 32
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    Digitale Medien
    Investigation of local order in unreacted DGEBA epoxy resin monomers by light scattering (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 327-344 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The existence of local order in two epoxy resins of the diglycidyl ether of bisphenol-A (DGEBA) type has been investigated using Rayleigh scattering and Brillouin spectroscopy. The resins differ in their molecular weight distributions and their relative concentrations of epoxide and hydroxyl groups. The complementary use of both techniques in elucidating the thermal behavior of local order is illustrated, and the use of the latter technique to study thermal acoustic phonons and hypersonic relaxation is discussed. Both techniques independently show that molecular aggregates exist in each resin system. The scattering-envelope dissymmetry shows that the resin with the high epoxide/hydroxyl group ratio contains aggregates up to 20 nm in size, and the low-ratio resin exhibits sizes up to 70 nm. These aggregates are thermally unstable in the temperature range studied (293-443 K). Dissolution in chloroform shows that these aggregates are reduced in size and that further structural changes occur which are dependent on solvent concentration. Aggregate volume fractions were determined for a range of aggregate size. Brillouin spectroscopy indicated that both resins exhibit hypersonic relaxation in the temperature range studied. The complex longitudinal moduli of the resins were superimposable under a WLF temperature transformation comparable to the difference in their static glass transition temperatures. Molecular aggregate size, number, and stability are related to the epoxide/hydroxyl ratio of the resins and the degree of intermolecular hydrogen bonding.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200214
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  • 33
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    Digitale Medien
    Reduced-variable mechanical characterization of styrene-butadiene rubber with varying crosslink density, temperature, and finite strain statesThis research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract No. NAS7-100, sponsored by the National Aeronautics and Space Administration.Corrected proofs received January 4, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 363-374 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A single master logarithmic stress relaxation curve of reduced modulus as a function of reduced time is established for a styrene-butadiene rubber (SBR) system, accounting for the effects of crosslinking density, temperature, and time. The results from recent tests involving uniaxial and various biaxial strain states at finite strain levels may be represented by a unique strain-energy function W of the Valanis-Landel separable symmetric type, \documentclass{article}\pagestyle{empty}\begin{document}$ W = \sum\limits_{i = 1}^3 {w(\lambda_i)} $\end{document} where the λi are principal extension ratios. These two representations demonstrate that the mechanical response of whole families of elastomeric materials may be predicted once a single member of the family is fully characterized.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200301
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  • 34
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    Digitale Medien
    Characterizing the kinetics of volume recovery in glasses by instantaneous temperature-jump experimentsThis work was supported by the U.S. Department of Energy, under Contract No. DE-AC04-76-DP00789 and by the National Science Foundation under Contract No. DMR 78-24185. (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 375-387 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: This article proposes a temperature-jump (T-jump) approach for characterizing the kinetics of volume recovery in glassy materials. The kinetic characterization is based on the Kovacs-Aklonis model. This incorporates a retardation-time spectrum which shifts according to both the temperature and the instantaneous volume. The proposed experiments involve measuring the change in recovery rate caused by an abrupt temperature jump. Although an analogous procedure has been used to determine the activation energy for linear viscoelastic creep, the analysis for volume recovery is complicated by its inherent nonlinearity. Nevertheless, accounting for the nonlinearity by a reduction of the time scale permits the T-jump results to be analyzed. In particular, the T-jump approach can be used to: (i) test a particular functional form for the shift factor and (ii) determine the previously unmeasurable parameter x, which defines the relative importance of the temperature dependence and the volume dependence in this function. In addition, numerical simulations indicate that the proposed method can be implemented in the laboratory.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200302
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  • 35
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    Digitale Medien
    Structure-property behavior of films containing disk spherulites: A model study (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 457-472 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Thin films of a polyester of lactic and glycolic acid were prepared to give controlled amounts of disk spherulites. The spherulite contents ranged from zero to 100% and were accurately measured. The stress-strain properties of the films were then determined at 60°C, i.e., about 20°C above the glass transition temperature Tg. The mechanical behavior varied quite systematically with spherulite content and displayed little dependence on spherulite size. It was found that much of the mechanical data could be reasonably well described by a simple composite model. In addition, the yield strain as well as the strain to break could be principally coupled to the deformation of only the amorphous phase. SEM and optical microscopy studies supported the above conclusion, also demonstrating that the isolated spherulites adhered well to the amorphous matrix and behaved as stress concentrators in the system when the deformation temperature was above Tg.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200308
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  • 36
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    Digitale Medien
    Model networks of end-linked polydimethylsiloxane chains. XIV. Stress-strain, thermoelastic, and birefringence measurements on the bimodal networks at very low temperaturesPresented in part at the 27th International Symposium on Macromolecules, Strasbourg, France. 1981. (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 473-480 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Bimodal networks consisting of very short and relatively long poiydimethylsiloxane (PDMS) chains were studied from 30 to -52°C in an attempt to elucidate the anomalous increases in modulus [f*] exhibited by such elastomeric materials at high elongations. Temperature was found to have very little effect on (i) the elongation at which the upturn in [f*] becomes discernible, (ii) the elongation at which rupture occurs, and (iii) the total increase in [f*] up to the rupture point. The standard force-temperature (“thermoelastic”) plots were linear, but gave values of the energetic contribution to the total force which were significantly smaller than those universally obtained on unimodal, long-chain PDMS networks. Birefringence-temperature relations were also found to be linear, and yielded values of the optical-configuration parameter and its temperature coefficient which were in satisfactory agreement with the corresponding values reported for unimodal PDMS networks. These results indicate that even at very low temperatures the observed increases in modulus (and consequent improvements in ultimate strength) are due to non-Gaussian effects arising from limited chain extensibility, rather than from intermolecular reinforcing effects such as strain-induced crystallization.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200309
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  • 37
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    Digitale Medien
    Increased water sorption of poly(methyl methacrylate) after removal of methanol (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 557-560 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200316
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  • 38
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    Digitale Medien
    A neutron scattering analysis: How does the conformation in polyethylene crystals reflect that in the melt? (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 561-578 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Neutron scattering data for melt-crystallized polyethylene have been analyzed in order to clarify to what extent the chain folding is randomly reentrant. No attempt has been made to specify the molecular conformation in every detail, and the emphasis is on distinguishing between different classes of conformation. The most random folding corresponded to a model where the folding is imposed solely by the criterion of the chain segments moving the least possible distance during the crystallization process (a “freezing-in” model). This has been shown not to be compatible with published data. For this model analytic calculations are possible based on the projection of a three-dimensional Gaussian distribution onto a plane. A subunit model is then proposed which requires substantial local rearrangement of the chain as it folds during crystallization, but where the distribution of the subunits within the whole molecule is imposed by the preexisting Gaussian chain of the melt. Arguments based on space filling considerations are invoked, with the postulate of a surface structure which is neither crystalline nor truly amorphous. Anything approaching a random switchboard model (e.g., the freezing-in model which we consider) is contrary to both space filling considerations and to the comparison of observed and calculated neutron scattering. The analytical calculation which was performed for the freezing-in model was employed so as to simplify calculations for the subunit model. For scattering intensities over a wide range of scattering angle it is deduced that only the structure within the subunit need be considered. Numerical computer calculations involving only a small number of stems were then carried out for a number of different subunit structures, and some general features are noted which restrict the type of model which can explain the data. As in previously published analyses, a very high proportion of adjacent folds is not compatible with the results. A row model for the stems within a molecule can achieve good agreement, either with straight rows or with a certain amount of “stagger” incorporated. Up to about 40% of the folds could be adjacent. Models based on two-dimensional random walks did not give good agreement.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200401
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  • 39
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    Digitale Medien
    Stress relaxation of a polymer solution in double-step shear deformations: A separate evaluation of the stress components due to entangled segments of different orientations (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 623-632 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: When two shear deformations γ1 and γ2 are successively applied to an entangled polymeric system, a composite temporary network is formed. In this article a simple method is proposed for evaluating separately the contributions from the component networks of different deformations, γ1 + γ2 and γ2, to the observed shear and normal stresses. The method is applied to literature data for a polystyrene solution. It is revealed that the entangled chain segments formed between the applications of two deformations relax very rapidly, while those formed prior to the first deformation do not relax for quite a long time. The result is in accord with the conjecture based on the tube model of entanglement that the chain ends lose their orientation as the chain creeps out of an oriented tube.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200405
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  • 40
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    Digitale Medien
    The use of chemical contrast in the SEM analysis of polymer blends (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 651-658 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A novel method for investigating the morphology of multiphase polymers is discussed. In this procedure, inherent differences in secondary and backscattered electron emission from the various components rather than topographical variations are used to produce image contrast. The combined use of various selective stains and energy-dispersive x-ray analysis to accentuate and positively identify individual phases is discussed. The effects of coating thickness and type and changes in accelerating voltage on image quality are also described.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200408
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  • 41
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    Digitale Medien
    The characteristic ratios of stereoirregular polybutadiene and polyisoprene (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 743-750 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The characteristic ratios of stereoirregular polybutadiene and polyisoprene have been evaluated by a combination of intrinsic viscosity and light-scattering measurements under θ conditions. The polydienes were synthesized by anionic polymerization and thus had near-monodisperse molecular weight distributions and were of uniform microstructure. The polybutadiene C∞ was found to be 5.1, which is in good agreement with the Abe-Flory predictions. However, the value of 5.1 for polyisoprene is somewhat higher than prediced by theory.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200415
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  • 42
    Digitale Medien
    Digitale Medien
    Styrene-acrylonitrile random copolymer in ethyl acetate (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 773-775 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200418
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  • 43
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    Digitale Medien
    Studies of magnetic resonance phenomena in polymers. I. The effects of free volume and segmental mobility on the motion of nitroxide spin probes and labels in poly(methyl methacrylate)This paper presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract NAS7-100 sponsored by the National Aeronautics and Space Administration, and supported in part by the Encapsulation Task, Low Cost Solar Array Project, and also in part by the RAD Task of the Solar Thermal Power System Project, funded by the Department of Energy. (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 763-772 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Thin films of spin-probed and spin-labeled poly(methyl methacrylate) (PMMA) have been examined by electron spin resonance (ESR) at X-band frequency (9.2 GHz) and at various temperatures. Direct spectral evidence is presented to indicate that the composite ESR spectra observed in a certain temperature range originate from two states of distinctly different mobility, one with slow motions corresponding to a glassy state and the other with fast motions corresponding to a liquidlike state. The coexistence of these two states at temperatures considerably below the glass transition temperature can be explained as a result of the effect of free volume in a solid polymeric glass.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200417
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  • 44
    Digitale Medien
    Digitale Medien
    An expression for local composition in polymer-solution thermodynamics (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 783-791 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: An expression for local composition which describes nonrandom interactions between unlike molecules in polymer solutions is proposed. This expression makes the nonrandom model compatible with the one-fluid hypothesis and satisfies the limits of randomness when experimental conditions evolve in such a way. Data on several binary systems are studied using this model which represents simultaneously activity and heat-of-mixing data.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200501
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  • 45
    Digitale Medien
    Digitale Medien
    Molecular aggregation of solid aromatic polymers. II. Mechanical properties of aromatic polyimide film (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 837-844 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Molecular aggregation of the aromatic polyimide poly(4,4′-oxydiphenylene-pyromellitimide) is influenced by the initial imidization temperature and by cold drawing. The effect of molecular aggregation in polyimides on their mechanical properties has been investigated. The density of a polyimide in which molecular aggregation gives an amorphous state is increased slightly by cold drawing. On the other hand, if molecular aggregation leads to a heterogeneous two-phase structure, the density is decreased by cold drawing. With increasing initial imidization temperature, the α absorption peak in dynamic tensile measurements becomes broader and smaller, and shifts to a higher temperature. From analysis of correlations between molecular aggregation and mechanical properties, it is concluded that the mode of molecular motion corresponding to the α dispersion in polyimide is a long-range cooperative motion of the main chain which is associated with the glass transition.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200506
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  • 46
    Digitale Medien
    Digitale Medien
    Phase relationships in a ternary solution composed of a solvent and two monodisperse homologous polymers (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 893-898 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Exact expressions are derived for the spinodal, critical conditions, and separation factor of a ternary solution consisting of a pure solvent and two monodisperse homologous polymers in which the Flory-Huggins interaction parameter χ depends separately on the concentrations of the polymer components. The results allow one to see the difference from previous expressions obtained with χ depending on the total concentration of the polymer, and are expected to be useful for experimental determination of the Gibbs free energy of ternary solutions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200511
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  • 47
    Digitale Medien
    Digitale Medien
    On the mechanism of fibril growth in polycarbonate and poly(methyl methacrylate) crazes (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 929-930 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200514
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  • 48
    Digitale Medien
    Digitale Medien
    Fluorescence depolarization in polymers: The microviscosity of bulk polybutadiene and of solutions in cyclohexane (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 953-959 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The reorientational relaxation of 9-cyananthracene fluorescent label molecules has been measured in bulk polybutadiene and solutions with cyclohexane by a fluorescent depolarization technique. The procedure adopted consists in the incorporation of an Arrhenius temperature dependence of the orientational relaxation time in the Perrin equation, thus obviating the necessity of an independent determination of the intrinsic polarization ratio P0 and enabling one to obtain the preexponential factors and the activation energies of the reorientational relaxation times. The most noteworthy result in our view is the validity of the Arrhenius equation for the effective microviscosity as opposed to the validity of the Fulcher-Vogel-Tamann equation with a glass point of T0 = 136 K for the shear viscosity of a polymer solution (90%).
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200603
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  • 49
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    Digitale Medien
    Birefringence of highly oriented fibers (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 981-987 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A spectrophotometric method was developed for measuring the birefringence of highly oriented synthetic fibers. This method surmounts the low birefringence limit of the standard quartz compensator method and the difficulties in interpretation of the photographic fringe method. A highly oriented aramid fiber gave birefringence values of 0.60-0.75 by this method, compared with 0.25 for polyester and 0.06 for nylon by other conventional methods. The operating principles and excellent results of this new method provide a basis for the extension of routine birefringence characterization to highly oriented fibers.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200606
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  • 50
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    Digitale Medien
    Three-dimensional crystalline order in an atactic comblike polymer (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1013-1018 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The production of oriented “crystalline” fibers of an atactic polymer, poly{1-[6-(4-biphenylyloxy)hexyloxycarbonyl]ethylene} is reported. The x-ray diffraction is consistent with a two-chain unit cell with a = b = 23.5 Å, c = 6.48 Å, and γ = 120. Although the cell is essentially hexagonal, the absence of screw symmetry along the polymer chain reduces the crystal symmetry to P A packing model consistent with these data is proposed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200609
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  • 51
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    Digitale Medien
    FTIR studies of calcium and sodium ionomers derived from an ethylene-methacrylic acid copolymer (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1069-1080 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A systematic study of the sodium and calcium salts of an ethylene-methacrylic acid copolymer is reported. Fourier-transform infrared spectroscopy (in the midinfrared region) is applied to the characterization of structural changes as a function of temperature and time of annealing. In the spectra of calcium ionomers, bands associated with carboxylate dimers are identified and assignments of specific spectral features to multiplets and clusters are discussed. The spectroscopic changes observed in the spectra of sodium ionomers differ somewhat from their calcium counterparts in that a single infrared band attributed to isolated carboxylate groups is observed. Assignments of specific bands to multiplets and clusters can, however, be made in a manner consistent with the interpretation of the spectra of calcium ionomers.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200614
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  • 52
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    Digitale Medien
    Structural studies of ultrahigh-modulus polyethylene using nitric acid etching and gel permeation chromatography. II. Influence of polymer molecular weight, draw temperature, and annealing (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1107-1128 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The technique of nitric acid etching followed by gel permeation chromatography has been used to determine the crystal length distribution in ultrahigh-modulus polyethylenes. The crystal length distribution has been studied as a function of draw ratio, polymer molecular weight, processing conditions, and annealing. The results confirm that although there is a considerable broadening of the crystal length distribution on drawing, the majority of crystals have lengths less that 500 Å. There are detailed changes in the length distribution due to changes in draw temperature, molecular weight, and annealing which are not always reflected in corresponding changes in the long period determined from small-angle x-ray scattering. Possible reasons for these discrepancies are discussed.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200702
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  • 53
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    Digitale Medien
    The entanglement network and craze micromechanics in glassy polymers (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1129-1141 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Crazes have been grown from crack tips in thin films of the following five polymers: polytertbutylstyrene (PTBS), polystyrene (PS), poly(styrene-acrylonitrile) (PSAN), poly(phenylene oxide) (PPO), and poly(styrene-methyl methacrylate) (PSMMA). These polymers represent a wide range of le values, where le is the chain contour length between entanglements. Quantitative transmission electron microscopy has been used to analyze the extension ratio λcraze and displacement profiles for these crazes. From these measurements the craze surface stresses have been computed by using the method of distributed dislocations. This analysis also permits an accurate measure of the level of the applied stress σ∞. These measurements show that the stress necessary for crazing increases as le decreases and that the higher surface stresses present at crack tips generate crazes that have higher λs than isolated crazes in the same polymers. Surface drawing is shown to be the dominant mechanism for craze thickening in all five polymers.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200703
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  • 54
    Digitale Medien
    Digitale Medien
    Shrinkage and retractive forces during the annealing of drawn low-density polyethylene (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1175-1192 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Shrinkage of unconstrained low-density polyethylene samples and the retractive stress of samples with ends fixed have been investigated as a function of the annealing time tA and temperature TA on material drawn at room temperature to draw ratios λ between 4 and 6. The shrinkage increases with tA and TA. The retractive stress on a sample annealed with ends fixed goes through a maximum as the sample is annealed and then drops to a limiting value which increases with TA as long as TA is at or below 80°C and rapidly decreases with higher TA. The drop from the maximum to the limiting retractive stress, slow at lower TA and rapid at higher TA, seems to be a consequence of rapid pulling of chain segments out of crystal block in which interfibrillar tie molecules are anchored. This process is facilitated by the high TA, which softens the crystal matrix. At constant end-to-end distance, the contour length of the tie molecules is irreversibly increased, and this causes a reduction in the contribution of the affected tie molecules to the overall retraction stress. Hence one finds a substantially higher retraction stress during first heating than during subsequent cooling and heating of the drawn sample.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200706
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  • 55
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    Digitale Medien
    Theoretical birefringence of ultraoriented polyethylene from model structure calculations (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1193-1205 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The birefringence of model structures of ultraoriented polyethylene has been calculated by using the point-dipole concept and the polarizability tensor of the methylene group derived recently by Pietralla. For well-oriented chains the birefringence is determined by the combination of a negative anisotropy of the polarizability tensor of the methylene group and a positive anisotropy of the Lorentz tensor, both with respect to the chain direction. As a consequence it decreases with increasing density. The results are in agreement with experimental values of Mead, Desper, and Porter. In the model the amorphous regions are regarded as a mixture of planar and helical segments arranged in nematiclike bundles which additionally may have a certain distribution of orientation. The birefringence is not much affected by defects which, on the other hand, strongly influence the ultimate mechanical properties.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200707
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  • 56
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    Digitale Medien
    Effect of substituents in the styrene ring on the dynamic mechanical relaxations of a styrene-crosslinked unsaturated polyester resin (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1223-1232 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The dynamic mechanical properties of a series of polyester resins made from a maleic/phthalic anhydride-based unsaturated polyester crosslinked with each of styrene, 4-methyl styrene, 4-ethyl styrene, 4-n-butyl styrene, 4-isopropyl styrene, tertiary butyl styrene, 4-chlorostyrene, and 3,4-dichlorostyrene were studied. The order of the α transition temperatures was as expected from that for the homopolymers, except in the case of the chlorostyrenes, for which dipolar interactions with the polyester chain may be important. The styrene bridges appeared to be involved in a steric interaction (and in the case of the chlorostyrenes, a dipolar interaction) with the β relaxing ester species. It is suggested that both the γ and γ′ relaxations involve similar interactions between the matrix and the relaxing moieties. For the 4-n-butyl styrene resin, an additional relaxation below -170°C was observed, and is ascribed to relaxation of the n-butyl group.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200709
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  • 57
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    Digitale Medien
    Polyelectrolyte solutions: Counterion condensation and intermolecular interactions (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1233-1247 
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    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: This article demonstrates that the neglect of nonlinear effects in the conventional counterion condensation theory for the double layer about a charged cylinder can be significant, especially for phenomena involving intramolecular or intermolecular interactions in dilute solutions. For concentrated solutions the Manning theory derives from a linearized superposition approximation for the potential, in contrast to the cylindrical-cell model, which explicitly treats interactions within an ordered array of parallel cylinders. A new theory which treats interactions explicitly while permitting disorder in two dimensions is presented, and predictions for the osmotic pressure are compared with those from the Manning and cylindrical-cell models.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200710
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  • 58
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    Digitale Medien
    Additive moduli for crosslinked epoxies (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1269-1278 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Ultrasonic measurements were made on a series of eight crosslinked polyepoxides over the temperature range from 0 to 60°C at a frequency of 2 MHz. From these measurements the bulk (K) and shear (G) moduli were calculated. These data were then analyzed in terms of molecular component properties. Proceeding by analogy with Rao's rule for liquids, the authors found that K is not an additive property but the function U = V(K/ρ)1/2γ is an additive property. Here V is molar volume, ρ is the density, and γ is the Gruneisen parameter (for interchain vibrations). A similar relation was found to hold for shear modulus. In particular, G is not an additive property but W = V(G/ρ)1/2g is an additive property, where g = (1/2α) (∂ InG/∂T)p - 1/2 is the shear analog of the Gruneisen parameter. Using U and W, calculations were made of K and G as functions of temperature for the eight epoxies. These results agree with the measured values within the experimental uncertainty of the measurements.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200713
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  • 59
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    Digitale Medien
    Dynamic birefringence studies of high-density polyethylene (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1279-1287 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A rheo-optical investigation has been carried out on a sample of high-density polyethylene (HDPE) in an attempt to examine the nature of the α-relaxation mechanism. Dynamic mechanical and bi-refringence behavior was measured over the frequency range of 0.008-4.3 Hz and temperature range -40 to 100°C. The dynamic mechanical and birefringence data were reduced to a reference temperature of 50°C by a combination of horizontal and vertical superposition. The significance of the vertical shift factor has been discussed extensively in previous papers and is not dealt with here. An Arrhenius plot was made of the log of the horizontal shift factor versus reciprocal temperature for the mechanical and optical data. The mechanical data exhibited three distinct regions, the slopes of which led to activation energies of 70, 90, and 150 kJ mol-1. The temperature at which these dispersions occurred suggested the observation of the β, α1, and α2 relaxation processes. The optical data contained two distinct regions from which activation energies of 55 and 95 kJ mol-1 were obtained. The high-temperature α2 process was not observed in the Arrhenius plot; however, a maximum in K′ and a change in sign of K″ probably reflects a contribution from the α2 relaxation mechanism.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200714
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  • 60
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    Digitale Medien
    Etude cinétique des effets de fluence énergétique, de débit de fluence, et d'effacement induits par des ions lourds et des photons γ dans le triacétate de cellulose (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1313-1326 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The kinetic interpretation of the damage produced by heavy ions (3684Kr and 1735Cl from 1 MeV/amu) and γ radiation in cellulose triacetate leads to an exponential dependence on the ion fluence. A comparison of the fading effect produced by heavy ions and γ rays shows that the heavy ions, unlike γ rays, cause irreversible damage. Finally, a nonlinear dependence on the flux of ions and γ rays is found in the kinetics of radiation damage. This result is contrary to the usual assumption that heavy-ion flux, like γ-ray flux, is additive, at least for the fluxes of 109-2 × 1010 ions/cm2s and dose rates of 103-104 Gy/h used in this work.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200716
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  • 61
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    Digitale Medien
    Observations par microscopie électronique de traces d'ions lourds dans le triacétate de cellulose (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1327-1340 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Tracks of heavy charged particles have been observed in cellulose acetate by conventional electron microscopy (100 kV) and by high voltage microscopy (1, 2 MV). The tracks are formed of successive islets following each other at distances of 70-150 Å. With the evolution of the diameter of these zones is shown the existence of a highly perturbed cylindrical volume (diameter 400 Å for the case of krypton) corresponding to regions in which free radicals have been created. The different techniques used do not allow observation of the latent track because of the complications of energetic phenomena: the electron beam current density being limited, the contrast is small and hence the resolution is restricted.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200717
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  • 62
    Digitale Medien
    Digitale Medien
    Distribution spatiale des dommages produits par les ions 3684Kr (1 MeV/amu) et 1735Cl (1 MeV/amu) dans le triacétate de cellulose (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1289-1311 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Our earlier results on ασ and heavy-ion-radiation damage in cellulose triacetate (CTA) are compared with those of previous authors on UV-and γ-radiation damage in the same material. Thus the common effects of these different methods of irradiation can be distinguished from those characteristic of the radiation employed. With heavy-ion radiation the production of stable radicals is accompanied by C - O cleavage. In the case of 3684Kr (1 MeV/amu) ions, the number of free radicals produced is investigated, without distinguishing the species, by using the scavenger technique in the solid phase, combined with UV spectroscopy. On the other hand, C - O cleavage is observed by IR spectroscopy, with its inherent selectivity. A statistical study shows that the experimental curves representative of the evolution of the optical transmittance ratio before and after irradiation L(N) versus the ion fluence N are of exponential type: $$ L(N) = \alpha e^{\beta N} $$ where β is a parameter related to the volume damaged by a single ion and, therefore, to the latent track size. The latter is approximated by a cylinder whose height is equal to the range of the ion. For 3684Kr8+ (1.1 MeV/amu) the track length is 21 μ. For each type, damages are localized within a radius of 250 Å for free-radical yields, 148 Å for cellulosic chain cleavages, 108 Å for deacetylation, and 100 Å for opening of pyrannosic rings. The track length is 14 μ for 1735Cl6+ (1 MeV/amu), while the radius of the cylinder in which free radicals are produced is only 80 Å.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200715
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  • 63
    Digitale Medien
    Digitale Medien
    Liquid-crystalline textures in binary and ternary block copolymer-solvent systemsCorrected proofs received May 3, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1341-1353 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A number of characteristic liquid-crystalline textures can be obtained in binary and ternary systems (i.e., including one or two solvents) based on polystyrene-poly(ethylene oxide) (PS-PEO) and polystyrene-polyisoprene block copolymers. These textures include oily streaks, myelinic figures, and vesicles, all characteristic of a lamellar structure; fan-shaped textures of cylindrical structure; and isotropic domains indicative of a cubic structure. Experimental conditions used to systematically produce the mesomorphic textures are described, and the rather critical solubility conditions which the solvents must meet are indicated. The rules and described procedures should be quite general and applicable to other copolymers as well. Finally, highly unusual examples of “pseudomorphosis” typical of liquid-crystalline textures occurring in bulk upon melting and crystallization of the PEO sequences in PEO-PS copolymers are also reported.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200801
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  • 64
    Digitale Medien
    Digitale Medien
    Thermodynamic properties of a polyelectrolyte solution containing a mixture of counterions of the same chargeCorrected proof received April 27, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1355-1364 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Electrostatic internal and free energies are calculated for the cell model of a polyelectrolyte solution having two kinds of counterions of the same charge but different size. The calculation is based on the solution of the Poisson-Boltzmann equation obtained previously. The electrostatic contributions to the internal and free energies are presented as functions of valences, radii, and mole fractions of counterions, and their application to interpretation of experimental results is discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200802
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  • 65
    Digitale Medien
    Digitale Medien
    Absolute integrated SAXS measurements during the crystallization of linear polyethyleneResearch sponsored by the Army Research Office (Durham) under Grant No. DAAG 29-77-G-0201 and by the Department of Energy, Division of Materials Science, under Contract W-7405-eng-26 with the Union Carbide Corporation.Corrected proofs received April 29, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1365-1369 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Absolute intensity measurements of a dynamic small-angle x-ray scattering from a linear polyethylene were carried out during polymer crystallization from melt in a temperature range of 113.5° to 124.5°C. The mean-square modulation of the electron density over the irradiated volume was evaluated and the feasibility of dynamic experimentation for crystallization kinetic analysis was established. The results provide an absolute value of mass density of the amorphous phase of a semicrystalline polymer at the crystallization temperature.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200803
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  • 66
    Digitale Medien
    Digitale Medien
    Effects of high-pressure CO2 on the glass transition temperature and mechanical properties of polystyreneCorrected proofs received May 20, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1371-1384 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Hydrostatic pressure usually increases the glass transition temperature Tg of a polymer glass by decreasing its free volume; if the pressurizing environment is soluble in the polymer, however, one might expect an initial decrease in Tg with pressure as the polymer is plasticized by the environment. Just such a minimum in the Tg of polystyrene (PS) is observed as the pressure of CO2 gas is increased over the range 0.1-105 MPa from both ultrasonic (1 MHz) measurements of Young's modulus E and static measurements of the creep compliance J. A time-temperature-pressure superposition law is obeyed by PS which allows a master curve for the compliance to be constructed and shift factors to be determined. A master curve for E is then obtained by using the Boltzmann superposition principle. The compliance J reaches a maximum, and E and Tg reach minima, at a CO2 pressure of ca. 20 MPa at both 34 and 45°C, which are above the critical temperature (31°C) of CO2. At the minimum, Tg is 41 at 45°C and 36 at 34°C, the larger depression at 34°C evidently corresponding to the higher solubility of CO2 at the lower temperature. The plasticization effect due to CO2 can be isolated by subtracting the effect of hydrostatic pressure alone from the experimental data. The results leave no doubt that at high pressures CO2 gas is a severe plasticizer for polystyrene.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200804
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  • 67
    Digitale Medien
    Digitale Medien
    Pressure-volume-temperature properties of blends of poly(2,6-dimethyl-1,4-phenylene ether) with polystyreneCorrected proofs received May 3, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1385-1397 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The pressure-volume-temperature (PVT) properties of blends of poly(2,6-dimethyl-1,4-phenylene ether) (PPO) with polystyrene (PS) have been studied experimentally in both the glassy and melt states at 0, 20, 40, 50, 60, 80, and 100% PPO content. In all compositions a strong glass transition was observed varying linearly with composition. For all but the 40% PPO composition this was the only transition, indicating molecular compatibility of the components in these blends. The 40% PPO composition showed a very weak second transition near the glass transition of pure PS. A small amount of phase separation may have occurred in this blend. The data for the glassy and melt states were fitted to an empirical equation of state based on the Tait equation. The volume of the melts at constant pressure and temperature showed a virtually linear dependence on composition. Any negative excess volume of mixing compatible with the data would have to be very small, smaller than expected from previous measurements in the glassy state. Various properties relating to the glassy and melt states and to the glass transition were evaluated and are discussed as a function of composition. It was found that most properties of the glasses could not be modeled by simple functions of composition.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200805
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  • 68
    Digitale Medien
    Digitale Medien
    Theoretical equation of state of polymer blends: The poly(2,6-dimethyl-1,4-phenylene ether)-polystyrene pairCorrected proofs received June 1, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1399-1408 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A recent theory of multicomponent fluids is applied for the first time to a compatible binary polymer blend. Good accord between the experimental pressure-volume-temperature measurements over the whole range of compositions by Zoller and theoretical predictions obtains. In particular, satisfactory predictions of high pressure from low-pressure information result. From the interplay between experiment and theory, the scaling quantities and thus the characteristic self- and cross interaction parameters are derived. The excess volumes are discussed and estimates of excess enthalpies presented. The theory predicts the actual enthalpy of the components or mixtures once the scaling parameters have been determined by means of volume-temperature data at atmospheric pressure. Enthalpy measurements to test these predictions are highly desirable.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200806
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  • 69
    Digitale Medien
    Digitale Medien
    Infinite-dilution oscillatory flow birefringence properties of polystyrene and poly(α-methylstyrene) solutionsCorrected proofs received June 3, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1409-1425 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Oscillatory flow birefringence (OFB) measurements have been carried out for an extensive series of solutions containing narrow-distribution, atactic, linear polystyrenes PS (10, 000 or 390, 000 Mw) or poly(α-methylstyrene) PMS (400,000 Mw) in a high-viscosity solvent, Aroclor 1248. The concentration ranges examined are such that the concentration dependence is obtained in both the “dilute” and “semidilute” regimes; the data are sufficiently precise to permit extrapolation to obtain for the first time the infinite-dilution properties. Various plotting formats are explored to determine an appropriate extrapolation procedure. The infinite-dilution OFB properties are compared with the bead-spring model (Zimm) theory which predicts quantitatively the frequency dependence of the observed properties for the PS and PMS solutions studied except for the high-frequency regime. The sensitivity and precision of the OFB experiment is such that the extrapolation curves-and the resulting infinite-dilution properties-show substantially less scatter than comparable visco-elasticity (VE) data. There is no evidence of a change in the character of the concentration dependence for the range of concentrations studied.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200807
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  • 70
    Digitale Medien
    Digitale Medien
    Stress response and energy dissipation in a linear viscoelastic material under periodic triangular strain loading (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1437-1442 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A general equation is derived for the stress response of a linear viscoelastic material to periodic strain excitation at constant strain rates. The energy dissipated in any cycle, especially in a steady-state loop, is discussed. The results can be used to analyze test results in determining mechanical properties of polymers. A simple Maxwell model and a three-parameter Maxwell model are used to illustrate the calculation of stress response and energy dissipation under constant-strain-rate loading.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200809
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  • 71
    Digitale Medien
    Digitale Medien
    Crystalline order in polyethylene: A 13C NMR CP/MAS solid-state T1 studyCorrected proofs received June 2, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1427-1435 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The carbon-13 spin-lattice relaxation times T1 of the crystalline components of four solid ethylene-octene copolymers have been studied as a function of thermal history, branching number, and branching distribution. Slowly cooled samples (1 deg/min from melt to room temperature) exhibited similar or longer T1s with respect to the same sample quench cooled (from the melt into 20°C water). The greater the degree of branching and the more homogeneous the branching distribution, the shorter were the observed crystal lattice T1s. Differences of up to a factor of 3 in T1 were observed for the same sample undergoing the two thermal treatments. Different degrees of branching homogeneity (for the same total number of branches) resulted in differences approaching a factor of 7 for samples with the same thermal history. These variations were attributed to the differing effects of side-chain disruption of the crystal lattice.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200808
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  • 72
    Digitale Medien
    Digitale Medien
    Effects of data analysis on accuracy and precision of GPC results (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1443-1451 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The effects of data imprecision and baseline uncertainties have been investigated by computer simulation of GPC data from a polymer sample with a truncated log-normal molecular weight distribution. If the data are very accurate, as few as five data points can be sampled without serious error in computed molecular weight averages. The number of data points required is much larger, however, if these are taken at equal increments of molecular weight rather than elution volume. The effects of noise can be counteracted by increasing the sampling frequency. Baseline uncertainties present a more serious problem, especially for broad-distribution samples. If the detected signal is too noisy to permit accurate location of the baseline, errors can be minimized by using a second, more sensitive detector to determine the peak start and end. It is very difficult to estimate M̄z and higher molecular weight averages accurately if the noise level is greater than 0.5%.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200810
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  • 73
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    Digitale Medien
    A study of the pressure-volume-temperature relationships of four related amorphous polymers: Polycarbonate, polyarylate, phenoxy, and polysulfone (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1453-1464 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The pressure-volume-temperature (PVT) relationships of bisphenol-A polycarbonate, polyarylate, and phenoxy were studied at pressures to 1800 kg/cm2 and in both the glassy and melt states. Earlier data on polysulfone are included in the analysis and discussion of the results. All four polymers contain the bisphenol-A residue in their repeat unit, together with a moiety of varying complexity, and are therefore somewhat related. At the glass transition, equations of the Ehrenfest type hold, provided the pressure dependence of the glass transition temperature is defined from the line obtained by intersecting the quasiequilibrium PVT relationship of the glass with the equilibrium PVT surface of the melt. The Prigogine-Defay ratio r = ΔκΔCp/TgVg(Δα)2 at P = O is unity within experimental error for all four polymers. The melt data were fitted successfully to the Simha-Somcynsky theory. Molecular parameters deduced from the reducing parameters vary in a reasonable manner among these four related polymers, lending support to the foundations of the theory.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200811
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  • 74
    Digitale Medien
    Digitale Medien
    The effect of anhydrous ammonia on the crystalline-state deformation of nylons 6 and 6,6 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1485-1496 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The aliphatic polyamides nylon 6 and 6,6 have been cold drawn by using the new concept of reversible plasticization with NH3. Two aspects were investigated: the effect of NH3 plasticization on the stress-strain behavior of nylon 6,6, and the extent of NH3 absorption as determined by x-ray analysis for the structurally simpler nylon 6. X-ray analysis shows that ammonia is absorbed preferentially by the amorphous phase and that the plasticization has a significant effect on the unit-cell orientation, the small-angle void scattering, and the interplanar spacings between sheets of hydrogen-bonded chains. The effect of plasticization was seen in the lower yield stress, the higher draw ratio (up to 8X) and tensile modulus (10 GPa) not attainable with unplasticized specimens.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200813
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  • 75
    Digitale Medien
    Digitale Medien
    Supermolecular structure of poly(ethylene oxide) fractions (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1465-1484 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The crystalline morphology, or supermolecular structure, of poly(ethylene oxide) has been studied as a function of molecular weight and crystallization conditions. Molecular weight fractions, covering the range 6 × 103 to 1 × 107 are used over the range of accessible temperatures for isothermal crystallization as well as for a large set of controlled nonisothermal crystallization conditions. A morphological map is constructed from these studies and compared with the literature results. Prior reports were primarily confined to low molecular weights, which restricted the generalization of the findings. In the present work, as a consequence of the extended molecular weight range, conditions are established for the systematic development of several different, well-defined, organized super-molecular structures as well as for highly crystalline but disorganized systems. Strong similarities are found between the results for poly(ethylene oxide) and previous reports for linear polyethylene. A generalization for all chain molecules is suggested.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200812
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  • 76
    Digitale Medien
    Digitale Medien
    Light-scattering studies on polystyrenes in isorefractive poly(methyl methacrylate)-toluene “solvents” (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1497-1502 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The rms radii of gyration 〈S2〉1/2 and second virial coefficients Γ2 of five monodisperse polystyrenes (M × 10-5 = 1.6, 2.8, 4.2, 6.6) were measured in isorefractive toluene-poly(methyl methacrylate) (M̄v = 4.0 × 104, 1.6 × 105, and 6.3 × 105) “solvents.” For a given PMMA, the concentration at which the θ condition (defined by Γ2 = 0) was reached was independent of PS molecular weight, but varied inversely with PMMA molecular weight (0.10, 0.056, and 0.023 g/mL, respectively). When this θ condition is reached by adding PMMA to toluene, the radii of gyration are decreased by only about 15%, much less than when it is reached by going to a poor, low-molecular-weight solvent. This reflects the exclusion of PMMA from the PS coils, the internal environment of which is essentially pure toluene.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200814
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  • 77
    Digitale Medien
    Digitale Medien
    Microphase separation in sulfonated polystyrene ionomers (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1503-1509 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Small- and wide-angle x-ray scattering results for a series of un-neutralized and neutralized sulfonated polystyrenes are presented for the range of sulfonation from 0 to 7.26 mol %. From the small-angle scattering it is shown that above the 3 mol % level for both the zinc and sodium salts, a Bragg spacing (37 Å) and diameter (6.9-8.4 Å) of the scattering unit can be calculated. When the concentration of salt is increased, there is no appreciable change in the latter two measurements. The wide-angle data indicate that the cations do not influence to any large extent the basic intramolecular and intermolecular structure of polystyrene. All the data are consistent with the onset of clustering above a critical ion concentration.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200815
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  • 78
    Digitale Medien
    Digitale Medien
    Optical and calorimetric analysis of stress-induced crystallization in natural rubber networksCorrected proofs received July 14, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1525-1531 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Stress-induced crystallization of natural rubber networks is studied. The analysis is carried out using two different experimental techniques and the results are compared. In particular, the microcalorimetric and photoelastic results seem to be in disagreement, but the disagreement can be resolved by assuming that organization phenomena take place even at strains less than the critical value at which thermally detectable crystallization occurs. It is believed that such organization phenomena give rise to highly defective crystallites which behave as nucleation agents in the crystallization process that is induced at larger strains.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200902
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  • 79
    Digitale Medien
    Digitale Medien
    Dynamical behavior of xanthan polysaccharide in solutionPaper presented at A.I.Ch.E. National Meeting, March 1981, Houston, TX.Corrected proofs received June 23, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1513-1524 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Dilute-solution hydrodynamic data for xanthan biopolymer in water suggest a rodlike molecule of dimensions 15,000 × 20 Å, and molecular weight 2.2 × 106 g/mol. Upon addition of NaCl to this system, the xanthan molecules self-associate to form stable aggregates. The native xanthan conformation can be thermally denatured to a disordered coil which can be stabilized at room temperature in 4M urea. The transition to semidilute solutions is manifested by discrete changes in the concentration dependence of diffusion coefficient and zero-shear viscosity at c ≈ 2.0 × 10-4 g/mL. At higher concentrations c ≥ 1.0 × 10-3 g/mL, the light-scattering and shear-viscosity data are qualitatively but not quantitatively consistent with predictions of the dynamical theory of Doi and Edwards for an isotropic entangled solution of rigid-rod molecules. Measurements of latex sphere diffusion in xanthan-water solution show a sudden retardation at c ≈ 1.0 × 10-3 g/mL, consistent with the cooperative formation of a motionally restricted network of long, thin, rigid fibers. At high shear rates, flow birefringence experiments indicate enhanced ordering of the xanthan chains in the semidilute regime.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200901
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  • 80
    Digitale Medien
    Digitale Medien
    Some evidence against the existence of the liquid-liquid transition. I. Transitions or dispersions: A quantitative explanation of one torsional braid log decrement peak (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1533-1550 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Some of the history of the proposed liquid-liquid transitions Tll and T′ll that have been reported to exist above the glass transition temperature Tg and the role played by the torsional braid analyzer are outlined. Confusion has been created by the failure to clearly distinguish such kinetic phenomena as viscoelastic and dielectric loss processes from thermodynamic transitions. It is shown quantitatively how the log decrement of an oscillating system can exhibit one more peak than is found in the loss tangent-temperature curve of a viscoelastic liquid.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200903
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  • 81
    Digitale Medien
    Digitale Medien
    Some evidence against the existence of the liquid-liquid transition. II. Properties of and measurements with a torsional braid analyzerCorrected proofs received July 2, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1551-1564 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A torsional braid analyzer (TBA) has been constructed for an investigation into the behavior of this instrument. An explanation was desired for the presence of the proposed second liquid-liquid transition T′ll peak in the log decrement-temperature curve of a low-molecular-weight polystyrene whose loss tangent increases monotonically as a function of increasing temperature at constant frequency. The response of the TBA was studied as a function of amplitude of oscillation, the nature of the braid, the braid tension, frequency, and the nature of the impregnant. All of the braids examined were shown to be extremely nonlinear in their response. Two peaks in the damping of the composite system as a function of temperature are attributed to the interaction between the impregnant properties and the nonlinear response of the glass fiber braid.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200904
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  • 82
    Digitale Medien
    Digitale Medien
    Some evidence against the existence of the liquid-liquid transition. III. The evaluation of the Tll event by differential scanning calorimetryCorrected proofs received July 12, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1565-1574 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The liquid-liquid transition Tll has been examined by using differential scanning calorimetry as the tool of measurement. The results presented show that for the case of polystyrene, the Tll event appears to be an artifact caused by the presence of volatile components. Purified samples of polystyrene, polydienes, and poly(1-butene) do not show the Tll transition.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200905
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  • 83
    Digitale Medien
    Digitale Medien
    Some evidence against the existence of the liquid-liquid transition. IV. The temperature dependence of shear viscosityCorrected proofs received July 2, 1982 (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1575-1583 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The viscosity data available for four anionically polymerized polystyrenes ranging in molecular weight from 1100 to 47,000 for the temperature range Tg to Tg + 100°C have been fitted by computer programs to both the Vogel, Fulcher, Tamman, and Hesse (VFTH) equation and to two optimum intersecting Arrhenius equations. The intersection point has been interpreted as a manifestation of a liquid-liquid transition. The fits to the VFTH equation were in every case found to be far superior. Systematic deviations of the residuals were observed for the best Arrhenius fits which indicate the lack of any validity for such a representation of the data.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200906
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  • 84
    Digitale Medien
    Digitale Medien
    Properties of aqueous salt solutions of poly(ethylene oxide) (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1585-1592 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The determination of the properties of aqueous salt solutions of poly(ethylene oxide) has been extended to cloud-point and θ-temperature measurements in sodium acetate, potassium fluoride, sodium thiosulfate, and potassium phosphate. The Hofmeister series for the decreasing effect of anion species in salting out the polymer is accordingly extended. However, the order of the effect depends on whether it is made on the basis of molar anion concentration the molar concentration of unit anion charge, or the ionic strength. Viscosity measurements on θ and non-θ solutions containing zinc sulfate, potassium fluoride, and potassium phosphate gave polymer dimensions (in addition to limiting viscosity numbers etc.), and characteristic ratios in good agreement with theoretical predictions (Abe and Mark), and enthalpy and entropy parameters χH and χs; the latter values, nominally -0.14 and 0.63, are identical at 298 K for the three salt species.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200907
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  • 85
    Digitale Medien
    Digitale Medien
    Small-angle x-ray and neutron scattering studies of amorphous polymer blends (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1593-1607 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Dilute mixtures of poly(ε-caprolactone) (PCL) in poly(vinyl chloride) (PVC), poly(p-iodostyrene) (PpIS) in polystyrene, and deuterated polystyrene (d-PS) in protonated poly(o-chlorostyrene) (PoCIS) were investigated by means of small-angle x-ray scattering and small-angle neutron scattering. The radii of gyration of PCL in PVC and of d-PS in PoCIS were found to be expanded over the θ values by 50 and 30%, respectively. Values of the second virial coefficient were positive although errors prevented definitive evaluation of the interaction parameter. PpIS was found to aggregate, with both the radius of gyration and molecular weight increasing with concentration. Concentrated mixtures of PCL and PVC were also investigated by using the Debye-Bueche correlation function analysis. Correlation distances indicated good mixing throughout the entire composition range.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200908
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  • 86
    Digitale Medien
    Digitale Medien
    Fractography of glassy networks formed from ethylene glycol dimethacrylate (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1609-1615 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Ethylene glycol dimethacrylate (EGDM) was polymerized to provide specimens suitable for three-point bending tests. Fracture surfaces were generally similar to those reported previously for relatively brittle materials such as silicate glasses. Attention was concentrated on linear features which lay in roughly parallel arrays in the direction of crack propagation. Generally the features had a circular cross section which, in a few cases, tapered to a fine point. In other cases partially detached features were observed to have an irregular radius of curvature. The two preceding observations were interpreted as evidence of localized plastic deformation. The linear arrays of surface features were explained by adoption of Preston's mechanism for formation of “stries” in brittle materials. However, this mechanism calls for a characteristic cross section which in the case of poly(EGDM) was replaced by a circular cross section. To account for this difference, localized plastic deformation was invoked.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200909
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  • 87
    Digitale Medien
    Digitale Medien
    Affinity of a hindered phenol antioxidant for reagents in hydrocarbon media: A low-temperature dielectric relaxation study (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1617-1622 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Low-temperature dielectric loss measurements reveal a tendency of 4-methyl-2, 6-di-tert-butyl phenol (the antioxidant BHT) to associate with various reagents in hydrocarbon media. The affinity with carbonyl groups appears to be particularly appreciable. It is suggested that this may have a bearing on the antioxidant activity of this type of compound.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200910
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  • 88
    Digitale Medien
    Digitale Medien
    NMR spectroscopic, osmometric, and viscometric study of association of syndiotactic poly(methyl methacrylate) in dilute solutions (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1623-1632 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Association of syndiotactic (s) poly(methyl methacrylates) (PMMAs) in toluene, benzene, and acetonitrile has been studied by NMR spectroscopy, osmometry, and viscometry. It was found that in solutions of highly syndiotactic PMMA in toluene, most of the polymer exists in the associated state. Association takes place by means of stereospecific intermolecular and intramolecular interactions of long parallel syndiotactic sequences. The minimum length of syndiotactic sequences necessary for association of s-PMMA in toluene is 7-8 monomer units. Viscosity data indicate that in dilute solutions the associated structures appear as large formations which do not have the character of compact particles. The formation of the aggregates of PMMA is a relatively slow process. A model of the structure of the aggregates of s-PMMA in toluene is proposed. As compared with that in toluene, the tendency to aggregation in benzene and acetonitrile is negligible. Integral parameters currently used for the characterization of polymer-solvent interaction, like “good” or θ solvent, are not suitable for predicting the tendency of s-PMMA to aggregation. The formation of aggregates evidently has some connection with the effect of the solvent upon the conformational structure of syndiotactic sequences.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200911
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  • 89
    Digitale Medien
    Digitale Medien
    Assignment of an anomalous peak in the brillouin spectrum of oriented polymer films (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1641-1645 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The origin of a previously unassigned peak in the Brillouin spectrum of an oriented polymer film has been clarified. This peak is shown to be due to backscattering from a quasitransverse acoustic phonon from the reflected laser beam. Studies of this peak are expected to provide the information concerning the birefringence effect of the oriented film.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200913
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  • 90
    Digitale Medien
    Digitale Medien
    Diffusion-controlled growth of lamellar crystals in an isotactic polystyrene-polyphenylene oxide blend (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1633-1639 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The growth rates of lamellar crystals grown onto preseeded fibrillar crystals (“shishes”) in isotactic polystyrene and blends of isotactic polystyrene (iPS) with polyphenylene oxide are followed by using transmission electron microscopy. The preseeded fibrillar crystals avoid the problem of timedependent primary nucleation. The time dependence of lamellar growth is investigated. At a concentration of 50% PPO in iPS, the lateral lamellar growth rate of the precipitating isotactic polystyrene crystals conforms to a time law characteristic of diffusion-controlled growth (R ∝ t1/2). Diffusion coefficients are estimated from the growth kinetics. The method could prove a simple means of measuring diffusion coefficients in polymer blends in which one component is crystallizable.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200912
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  • 91
    Digitale Medien
    Digitale Medien
    Studies of the effect of orientation on the elastic constants of stretched and hydrostatically extruded polychlorotriflouroethylene: A reorientational model in semicrystalline polymers (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1647-1658 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A reorientational model of polymer solids is given. The solid is described as a collection of small, orientable units. The elastic constants of the oriented polymer are given as a combination of the elastic constants of the orientable units and of the orientation parameters 〈P2(cosθ)〉 and 〈P4(cosθ)〉. The elastic constants of stretched and hydrostatically extruded samples of polychlorotriflouroethylene are obtained with Brillouin light scattering. These are fitted to the model and the orientation parameters are calculated. The elastic constants from the extruded samples are fit well by the model but the fit to the stretched film is less satisfactory. Hydrostatic extrusion in polymers is thus assumed to be a reorientation process in the amorphous phase, but the stretching process is not completely reorientational.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200914
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  • 92
    Digitale Medien
    Digitale Medien
    Entanglements and elasticity in polybutadiene networks (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1659-1668 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Polybutadiene networks were prepared by peroxide crosslinking of monodisperse 1,4-polybutadienes both in solution and in bulk. The effect of the entangled sol fraction on the elastic modulus of high-molecular-weight polybutadiene was observed in stress relaxation measurements. Sol fraction was shown to make a large contribution to the Mooney-Rivlin 2C2 term. This effect was also observed on the molecular level in NMR spin-spin relaxation measurements. For networks crosslinked in bulk the stress relaxation measurements suggest the presence of trapped entanglements. The 2C2 term is insensitive to sol extraction in these networks. NMR spin-lattice relaxation measurements in the rotating frame at 4.68 kHz verify the presence of additional effective crosslinks in these networks.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200915
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  • 93
    Digitale Medien
    Digitale Medien
    The measurement of crystallite size in ultrahigh-modulus polyethylene (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1677-1685 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Crystal length determinations have been undertaken on ultrahigh-modulus linear polyethylene fibers by dark-field electron microscopy. There is good agreement between the results and those obtained from wide-angle x-ray diffraction line broadening. The crystal length distributions from the dark-field microscopy are also consistent with those determined by nitric acid etching. The significance of the present results is considered in the light of recent proposals for the structure of these materials and the achievement of high modulus.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200917
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  • 94
    Digitale Medien
    Digitale Medien
    Crystallization of trans-1,4-polyisoprene (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1669-1676 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Crystals of fractionated trans-1,4-polyisoprene (TPI) were grown from amyl acetate solution at two weight fractions, 5.7 × 10-4 and 0.011; for the lower concentration a precooling followed by heating and then crystallization at temperatures in the 10-32°C range was used, while for the higher concentration this method and direct crystallization at a temperature TC in the 0-32°C range were employed. The precooling method yielded samples crystallized in the α form, while direct crystallization led to formation of β-TPI at low TC and α at higher TC. The value for the DSC endotherm, characteristic of α-form melting, increased with increasing TC, with a shift to lower values with increasing concentration for precooled samples. A β to α transformation was found to occur for synthetic unfractionated TPI when swollen with amyl acetate at 35°C for 17h. Swelling in n-butyl acetate for one day at 25°C or 17 h at 35°C also led to this transformation. From experimental results 74°C is chosen as the temperature at which the α and β forms coexist in the bulk, and this is used to calculate the enthalpy of fusion of β-TPI, yielding a value of 8.6 kJ mol-1.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200916
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  • 95
    Digitale Medien
    Digitale Medien
    The effect of interlamellar forces on the longitudinal acoustic mode of polyethylene crystals (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1687-1693 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The fold periods and longitudinal acoustic modes [LAMs] for isothermally crystallized polyethylene (PE) single crystals were determined in the dried state and in the presence of decalin and silicone oil. Upon swelling with decalin, the fold period increased by 7% while the LAM peak frequency decreased by approximately 1 cm-1. Several possible explanations for the change in LAM frequency are discussed but the exact interpretation is open to question. No change in fold period was observed upon soaking a dried crystal mat in silicone oil. This fold period invariance along with the fact that silicone oil has no effect on the melting point of PE crystals indicates that there is no significant interaction between the oil and the methylene groups on the crystal surface. The effect of suspending crystals (which have never been dried down) in silicone oil should only be to increase the average interlamellar distance and, therefore, to reduce any interlamellar forces. It is shown that the LAM peak frequency for crystals suspended in silicone oil is the same as that for the dried crystals, indicating that interlamellar forces do not exert a significant perturbing influence on the LAM of polyethylene crystals.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200918
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  • 96
    Digitale Medien
    Digitale Medien
    Polymerization and reptation, an analytical treatment (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1695-1708 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Free-radical polymerization without crosslinking is considered. By taking the chain length as a continuous variable the reaction kinetics is treated in a simple way for the stationary state. Equations for instantaneous average degrees of polymerization and related quantities are generalized to allow for chain-length dependence of the termination rate constant. For the Ito model, which treats reptation-controlled termination, approximate versions of these equations are derived in the limits of low and high conversion. The observed structure in the peak of the gel permeation chromatograms is shown not to be related to the bimodality in the instantaneous molecular weight distribution. None of the results is very sensitive to the precise reptation behavior.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200919
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  • 97
    Digitale Medien
    Digitale Medien
    Bimodal molecular weight distributions of a branched condensation polymer (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1709-1716 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Gel permeation chromatograms of a hindered-phenolic, branched condensation polymer display pronounced bimodality at high conversion. The true molecular weight distributions, obtained by means of a GPC calibration curve based on narrow-distribution fractions, exhibit corresponding anomalous high-molecular-weight “shoulders.” These results are discussed in terms of preferential aggregation and reaction of the higher-molecular-weight species during the polymerization, promoted by intermolecular hydrogen bonding in the apolar reaction medium.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200920
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  • 98
    Digitale Medien
    Digitale Medien
    Fluorescence studies of polymer blends: Effect of host matrix on copolymers of 1-naphthyl alkyl methacrylates and 9-anthryl methyl methacrylate (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1749-1753 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200923
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  • 99
    Digitale Medien
    Digitale Medien
    A new look at the crystallization of polyethylene. II. Crystallization from the melt at low supercoolings (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1717-1732 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: This article is part of the general project laid out in Part I (ref. 9) and is concerned with obtaining information on primary (unthickened) crystals of polyethylene formed at low supercoolings. For this, a technique had to be devised by which crystallization could be speeded up so as to eliminate or at least reduce lamellar thickening. Indeed we were able to increase the rate of crystallization by an order of magnitude using a technique which we have called enhanced self-nucleation. Using this technique we find that when viewed under an optical microscope, spherulites crystallize uniformly over the field of view, and not, as is usual, by a radial growth process. Isothermal crystallization in bulk linear polyethylene has been studied by means of the enhanced self-nucleation technique as a function of crystallization time by using Raman LAM and melting points to assess variations of fold length Data have been obtained at very much shorter times than before. At short times, we find a constant fold length; at longer times the crystals thicken linearly with the logarithm of time. Values of the initial fold length for crystallization temperatures between 118 and 130°C are presented. Associated with the thickening at short times we find an induction time which increases with temperature.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200921
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  • 100
    Digitale Medien
    Digitale Medien
    A neutron scattering analysis: How does the conformation in polyethylene crystals reflect that in the melt? (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1755-1755 
    Details
    ISSN: 0098-1273
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1982.180200924
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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