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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 2019-2029 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A sample of commercial atactic polypropylene was extracted with ether and the residue extracted with boiling n-heptane. Six fractions of the heptane-soluble material, which is very similar to that obtained by heptane extraction of isotactic polypropylene, were obtained by stepwise addition of acetone to a solution in cyclohexane. Densities, melting points, and x-ray photographs of the fractions and the unfractionated material were obtained and infrared absorption spectra used to estimate tacticity. Molecular weights, determined by means of a vapor pressure osmometer, ranged from about 3000 to about 25,000. That of the fraction of highest molecular weight was in good agreement with a separate determination by means of osmotic pressure measurements. Separation in fractionation occurred in order of decreasing molecular weight and increasing crystallinity as estimated from densities and x-ray photographs. Tacticity also seems to increase with decreasing molecular weight. Melting points of the fractions were not entirely in the order expected from their molecular weights and estimated crystallinities, and it is possible that low DP isotactic material may be preferentially concentrated in the highest molecular weight fraction. It is emphasized that the unfractionated material may contain polymers possessing a range of order intermediate between those of purely atactic and purely isotactic polymer and that refractionation may be required in order to characterize the material completely.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 1121-1132 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Reduced melting point and swelling measurements, involving heptane-soluble material from atactic polypropylene and over thirty liquids of differing chemical type, are reported. A value of 578 ± 40 cal. is obtained for the molar heat of fusion of a crystalline repeat unit which is much lower than values given for isotactic polypropylene. Some reasons for the low value are considered. Values of the polymer-solvent interaction parameter χ1 for systems involving alkylbenzenes and n-alkanes suggest a solubility parameter of 7.9 ± 0.1 (cal./cc)1/2 for the polymer. These values of χ1 decrease with increasing molar volume of liquid. Polar liquids of comparable solubility parameter or molar volume are associated with higher values of χ1. Intrinsic viscosities and values of the slope constant k′ are given for fractions in the molecular weight range 3,000-25,000 and six solvents at 25°C. The results suggest the following order of solvent power: cyclohexane ≈ cyclohexene 〉 methylcyclohexane 〉 trichloroethylene 〉 decalin 〉 carbon tetrachloride. Intrinsic viscosities are higher than those generally obtained for flexible polymers of comparable molecular weight, and the values of the Mark-Houwink exponent appear to be high. Some reasons for these high values are considered.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 2619-2630 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Osmotic, viscometric, and initial phase separation studies of dilute solutions of poly-(vinyl chloride) in cyclohexanone, cyclopentanone, tetrahydrofuran, morpholine, nitrobenzene, and tetrahydropyran are reported together with some swelling measurements involving these solvents and dioxane, acetone, and methanol. Values of the polymer-solvent interaction parameter χ1 obtained from osmotic and swelling measurements suggest the order of solvent power for poly(vinyl chloride) to be cyclohexanone 〉 cyclopentanone 〉 tetrahydrofuran 〉 morpholine 〉 nitrobenzene 〉 tetrahydropyran. A similar order is suggested by the volumes of hexane required to cause initial phase separation. Values of intrinsic viscosity and of the viscosity slope constant k′ give somewhat different orders of solvent power. Reasons for differences in order are considered. The correlation of the volume of hexane required to cause initial phase separation with χ1 is discussed and it is suggested that the polymer is solvated in solution. Other factors affecting the solvent power of solvents for poly(vinyl chloride) would appear to include the bulk and the solubility parameter of the solvent.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 15 (1955), S. 305-319 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Absorption of solvent and swelling by nitrocellulose fibers and films, in binary solventhexane mixtures of varying concentration and involving ketones, acetates, and phthalates, have been compared. Equilibrium is less rapidly attained with films. With solvents of smaller molecular size the equilibrium absorption of fibers and films, at a given concentration, is the same, suggesting that all regions of the nitrocellulose are accessible to such solvents. With solvents of larger molecular size lower equilibrium absorption values are obtained with films, suggesting that only certain regions are accessible to these solvents and such accessibility is less in films. Where absorption values are similar, swelling of films and fibers are comparable and similar modes of solution are observed. The assumption that no hexane is absorbed appears to be justified at lower solvent concentrations, but at higher concentrations the mixture in equilibrium with the nitrocellulose may be imbibed. Assuming such imbibition, the relationship between swelling or solvent power and cohesive energy density of solvent is interpreted in terms of interaction between solvated polymer and mixture.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 29 (1958), S. 37-52 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Heats and entropies of dilution of dilute solutions (concentration range 0.2-1.0 g./100 ml.) of cellulose acetate, ethyl cellulose, and cellulose nitrate, of similar degrees of substitution and polymerization, in a number of representative solvents, have been obtained from temperature coefficients of osmotic pressure. In some cases, degradation of polymer at the higher temperature used seems possible and an attempt is made to allow for this in the estimation of values of ΔH̄1 and ΔS̄1. Heats of dilution for the cellulose acetate and ethyl cellulose systems are generally endothermal, those for the cellulose nitrate systems being exothermal. Entropies of dilution are less than those obtained for comparable systems containing less polar and more flexible polymers. Those for the cellulose nitrate systems do not differ much from “ideal” values. The value of ΔH̄1/φ22, where φ2 is the volume fraction of polymer calculated from the density of the bare polymer, for each cellulose acetate system and most of the ethyl cellulose systems seems to be effectively independent of concentration. Values for the cellulose nitrate systems seems to be effectively independent of concentration. Values for the cellulose nitrate systems become less negative as the concentration increases. Values of ΔH̄1 for the cellulose acetate and ethyl cellulose systems are generally in the order to be expected from the solubility parameters of the solvents and polymers. ΔS̄1/φ22 may vary with concentration in a manner rather similar to that suggested by simpler lattice theories. These results are tentatively interpreted in terms of solvation of polymer and possible endothermal mixing of solvated polymer and solvent. Although values of the entropy contribution to the interaction parameter χ1 for the cellulose acetate and ethyl cellulose systems are not always inagreement with the predictions of simpler lattice theories it is possible, if solvation, segment size, and chain stiffness are allowed for, that the thermodynamic properties of dilute solutions of cellulose derivatives may be at least qualitatively interpreted in terms of such theories.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 5 (1950), S. 91-109 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 18 (1955), S. 63-86 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Preferential absorption and swelling by cellulose acetate in binary solvent-type liquid/hexane mixtures has been studied at 25°C. Secondary cellulose acetate, of acetic acid yield 53.7%, was used in fibrous form and as film. Triacetate, prepared by nondegradative acetylation of the secondary, was also used. Factors affecting preferential absorption by the fibrous secondary acetate seem to include the activity of the solvent-type liquid and its chemical type, the swelling power of the mixture, and steric effects. Preferential absorption of ketones and esters other than methyl formate appears to be independent of both acetyl content and structure. Absorption of methyl formate, acetic acid, and heterocyclic bases by the triacetate is less, at all concentrations, than by the secondary acetate. At low concentrations cresols and chlorinated hydrocarbons are absorbed to a smaller extent by the triacetate but at higher concentrations the reverse is the case, such variations in absorption being ascribed to steric effects and to the elimination of hydroxyl groups on complete esterification. Absorption by the secondary acetate films also suggests steric effects. Comparison of the measured weight of films with that estimated from the change in composition of the mixture following absorption, assuming no hexane to be absorbed, Suggests that this assumption is true at low concentrations. At higher concentrations, leading to high degrees of swelling or to gelatinization, the mixture seems to be imbided. There is no general relationship between swelling and the δ value of the solvent-type liquid but δ values for the mixtures just causing complete solution of the acetates are not very different when the mixtures involve solvents of similar chemicals type.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 23 (1957), S. 23-46 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Osmotic pressure, initial phase separation, and viscosity results are presented for dilute solutions of cellulose nitrate, cellulose acetate, and ethyl cellulose, using polymers of similar molecular weight and degree of substitution. A fairly wide range of solvents has been used in each case. Osmotic pressure results suggest molecular dispersion of polymer in most solvents but there is evidence for association of ethyl cellulose in aromatic hydrocarbons. Values of the Huggins μ are obtained and, for systems involving cellulose nitrate and ethyl cellulose in homologous series of ketones and acetates, seem to fall to a minimum and then increase on ascent of each series. It is suggested that the heat term in μ should include an exothermic contribution arising from solvation in addition to an endothermic contribution resulting from mixing of solvated polymer and solvent. It is tentatively suggested that, in a homologous series of solvents, the entropy and exothermic contributions may not vary much and that the variation of μ may arise from varying endothermic contributions. The volumes of hexane required to cause initial phase separation of the nitrate and acetate from solution increase with solvent power, as estimated from μ, but with ethyl cellulose the volumes tend to decrease. It is suggested that solvated polymer may separate from solutions involving polar solvents and, making certain assumptions, estimates are made of the solubility parameters of the polymers separating. Those for cellulose nitrate vary markedly with solvent. The variation of solubility parameter with solvent is less with cellulose acetate and ethyl cellulose but in the latter case values for polymer separating from polar solvents are less than from nonpolar. Comparison of these estimated solubility parameters with those of the solvents and hexane suggests that the volumes of hexane required to cause initial phase separation will only serve as measures of solvent power if the solubility parameters of solvents and precipitant all lie on the same side of that of the polymer separating. This seems to be so for cellulose acetate and possibly the nitrate but not for ethyl cellulose. Comparison of viscosity parameters and values of μ suggests that in certain cases both [η] and the initial slope of the plot of ηsp/c against c increase with solvent power. Other suggested viscosity measures of solvent power do not seem to be generally applicable. Some variation of chain configuration with solvent seems probable. Solvation, solvent type and association of polymer may also affect the viscosities of dilute solutions of cellulose derivatives.
    Additional Material: 13 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 9 (1952), S. 472-475 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 27 (1958), S. 459-472 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Osmotic pressure of dilute solutions (c≤1.0 g./100 ml.) of a fraction from a secondary cellulose acetate in representative solvents have been measured at two or three temperatures. Number-average molecular weights in acetone, aniline, methyl acetate, and pyridine do not vary with temperature but are significantly higher in methyl acetate in which association of polymer is possible. Molecular weights in acetic acid, nitromethane, and dioxane decrease with increase of temperature presumably because of degradation. Values of ΔF1, ΔH1, and ΔS1 have been estimated from temperature coefficients of osmotic pressure. All the systems are endothermal. It is suggested that the polymer is fully solvated and that solvated polymer and solvent mix with absorption of heat. With the exception of the aniline system, values for which are high, values of ΔH1 appear to be in the order to be expected from the solubility parameters of solvent and solvated polymer. ΔH1 and ΔS1 decrease with increase of temperature in all cases except that of acetic acid. ΔH1/φ22, where φ2 is the volume fraction of polymer, seems to be effectively constant at each temperature. Values of ΔS1 are greater than “ideal” values but are less than those obtained for comparable systems containing more flexible and less polar polymers. ΔS1/φ22 decreases with increase of concentration but in some cases there is an increase at the highest concentration. ΔF1 becomes more negative with increase of temperature. It would seem that both entropy and heat terms contribute to the value of the interaction parameter χ1. It is possible, if solvation and the segment size and stiffness of chains are taken into account, that approximate lattice theories may apply to solutions of cellulose derivatives at lower concentrations than in cases of more flexible and less polar polymers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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