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  • Articles: DFG German National Licenses  (3,577)
  • Electronic Resource  (3,577)
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  • 1990-1994  (3,577)
  • 1991  (3,577)
  • Polymer and Materials Science  (3,577)
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  • Articles: DFG German National Licenses  (3,577)
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  • Electronic Resource  (3,577)
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  • 1990-1994  (3,577)
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  • 101
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1883-1888 
    ISSN: 0887-624X
    Keywords: guanine containing monomers ; N6-acetylguanine containing monomers ; guanine derivatives ; monomer synthesis ; biomimetic monomers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of four new monomers containing guanine or a guanine precursor was achieved. These were two isomeric acid ester derivatives of guanine and two isomeric vinyl ether derivatives of N2-acetylguanine. In the case of the synthesis of the guanine acid esters IV and V, it was necessary to prepare first the guanine alcohol derivatives II and III. These N-7 and N-9 isomeric alcohols of guanine were separated by fractional crystallization. Subsequent esterification of these alcohols with maleic anhydride gave the desired products. In the other case, N2-acetylguanine was alkylated with 2-chloroethyl vinyl ether to yield the N-7 and N-9 isomer VI and VII, respectively. These were separated using flash column chromatography.
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  • 102
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1925-1931 
    ISSN: 0887-624X
    Keywords: new synthetic method ; polyamide-imides ; N,N′-bis(trimethylsilyl) diamines ; 4-chloroformylphthalic anhydride ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of N,N′-bis(trimethylsilyl)-substituted aromatic diamines with 4-chloroformylphthalic anhydride in various solvents at a temperature range between 10 and 70°C afforded polyamide-amic acid trimethylsilyl esters having inherent viscosities of 0.8-1.4 dL/g. Transparent and flexible films of the silylated precursor polymers were obtained by casting directly from the polymer solutions. Desilylation of the silylated polymers with methanol resulted in the formation of the corresponding polyamide-amic acids. Subsequent thermal imidization of the silylated precursor polymers with the elimination of trimethylsilanol afforded yellow, transparent, and tough films of the aromatic polyamide-imides. The thermal conversion of the silylated precursor polymer to polyamide-imide proceeded almost as rapidly as that of the corresponding polyamide-amic acid prepared by a conventional method from the parent aromatic diamine and 4-chloroformylphthalic anhydride.
    Additional Material: 5 Ill.
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  • 103
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1949-1953 
    ISSN: 0887-624X
    Keywords: chromium catalysts ; Phillips type catalysts ; Lewis acidity ; polyethylene catalysts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From literature data it is concluded that the rate of the reduction, alkylation, polymer chain growth, and chain transfer reactions of three chromium(II) and one chromium(III) surface species all increase with decreasing electron density at the chromium ion. This electron density has previously been measured by the IR shift of the stretching vibration of one CO molecule terminally adsorbed on these chromium ions. It is observed that the reduction half time decreases proportional to the increasing Lewis acidity and that the rate of the polymer chain growth reaction increases exponentially for three chromium surface species with increasing CO stretching vibration. Due to the large difference of the polymer chain growth rates for the two chromium (II) species (Ad and Cd), common in the normal Phillips catalyst, both contribute almost equally to the polymer product, although the Ad species outnumbers the Cd one by more than 3 to 1.
    Additional Material: 4 Ill.
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  • 104
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1987-1990 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 105
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1595-1601 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of ethylene/propylene copolymerization catalyzed by (ethylene bis (indeyl)-ZrCI2/methylaluminoxane) has been investigated. Radiolabeling found about 80% of the Zr to be catalytically active. The estimates for rate constants at 50°C are k11 = 1104 (Ms)-1, k12 = 430 (Ms)-1, k22 = 396 (Ms)-1,k21 = 1020 (Ms)-1, and kAtr,1 + kAtr.2 = 1.9 × 10-3 s-1. Substitution of trimethylaluminum for methylaluminoxane resulted in proportionate decrease in polymerization rate. The molecular weight of the copolymer is slightly increased by loweing the [Al]/[Zr] ratio, or addition of Lewis base modifier but at the expense of lowered catalytic activity and increase in ethylene content in the copolymer. Lowering of the polymerization temperature to 0°C resulted in a doubling of molecular weight but suffered 10-fold reduction in polymerization activity and increase of ethylene in copolymer.
    Additional Material: 7 Ill.
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  • 106
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1585-1593 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of metallocene/methylaluminoxane (MAO) catalysts have been compared for ethylene/propylene copolymerizations to find relationship between the polymerization activities, copolymer structures, and copolymerization reactivity ratio with the catalyst structures. Stereorigid racemic ethylene bis (indenyl) zirconium dichloride and the tetrahydro derivative exhibit very high activity of 10 7 g (mol Zr h bar)-1, giving copolymers having comonomer compositions about the same as the feed compositions, molecular weights increasing with the increase of ethylene in the feed, random incorporation of comonomers, and narrow molecular weight distribution indicative of a single catalytic species. Nonbridged bis (indenyl) zirconium behaved differently, favoring the incorporation of ethylene over propylene, producing copolymers whose molecular weight decreases with the increase of ethylene in the feed, broad molecular weight distribution, and a methanol soluble fraction. This catalyst system contains two or more active species. Simple methallocene catalysts have much lower polymerization activities. CpTiCl2/MAO produced copolymers with tendency toward alternation, whereas Cp2HfCl2/MAO gave copolymer containing short blocks of monomers.
    Additional Material: 7 Ill.
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  • 107
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly[(4-N-ethylene-N-ethylamino)-α-cyanocinnamate] was prepared by solution esterification of (4-N-ethyl-N-(2-hydroxyethyl) amino)-α-Cyanocinnamic acid and by melt transesterification of ethyl (4-N-ethyl-N-(2-hydroxyethyl) amino)-α-cyanocinnamate. The melt transesterification generally yielded polymer with a number-average molecular weight of about 10,200 by gel permeation chromatography (GPC) versus polystyrene standards. The polymer was found to be amorphous with a glass transition temperature of about 103°C by differential scanning calorimetry (DSC). The solution esterification generally gave a polymer with a number-average molecular weight of about 2200 by GPC versus polystyrene standards. This polymer was found to have a glass transition temperature varying between 60 and 90°C by DSC. The infrared (IR) spectrum of the polymer made from both methods were analyzed in detail. The 1H- and 13C-NMR spectra of the meltsynthesized ethyl cinnamate derivative polymer are consistent with the reported structure.
    Additional Material: 6 Ill.
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  • 108
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1649-1660 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have synthesized model compounds representing the repeating units of a polyamic acid prepared from pyromellitic anhydride and an aromatic amine. They were characterized with HPLC, 1H and 13C liquid and solid NMR and FTIR. The Kinetic study of the ring dehydration reaction of model compounds showed that the reaction paths were very different, depending on the experimental conditions (isotherms, liquid, or solid states). They could lead to a deterioration of the polyamic of the polyamic acid by the formation of side reactions. These reactions could predominate as a result of the existence of an equilibrium between the amic acid group and starting monomers.
    Additional Material: 13 Ill.
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  • 109
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1675-1680 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three benzyl p-hydroxyphenyl methylsulfonium salts with different counter anions were synthesized as novel latent thermal initiators. Syntheses of the sulfonium salts (2) were performed by the reaction of p-hydroxyphenyl methyl sulfide with benzyl chloride followed by exchange of the counter anion (Cl-) with SbF-6 (2a), PF-6 (2b), or BF-4 (2c). In the bulk polymerization of glycidyl phenyl ether (PGE) with 2, initiator activity of the sulfonium salts was evaluated by comparison with that of benzyl tetramethylenesulfonium hexafluoroantimonate (1, R = H). Among the initiators, 2a showed the highest activity, and was much more active than 1 (R = H). Since the polymerization of PGE with 2a proceeded efficiently at more than 80°C but not at all at less than 60°C, 2a was suggested to be a good latent thermal initiator.
    Additional Material: 3 Ill.
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  • 110
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1697-1706 
    ISSN: 0887-624X
    Keywords: fumaramide ; radical polymerization ; substituted polymethylene ; radical co-polymerization ; monomer reactivity ratios ; chain rigidity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical polymerization of N,N,N′,N′-tetraalkylfumaramides (TRFAm) bearing methyl, ethyl, n-propyl, isopropyl, and isobutyl groups as N-substituents (TMFAm, TEFAm, TnPFAm, TIPFAm, and TIBFAm, respectively) was investigated. In the polymerization of TEFAm initiated with 1,1′-azobiscyclohexane-1-carbonitrile (ACN) in benzene, the polymerization rate (Rp) was expressed as follows: Rp = k [ACN]0.28 [TEFAm]1.26, and the overall activation energy was 102.1 kJ/mol. The introduction of a bulky alkyl group into N-substituent of TRFAm decreased the Rp in the following order: TMFAm 〉 TEFAm 〉 TnPFAm 〉 TIBFAm 〉 TIPFAm ∼ 0. The relative reactivities of these monomers were also investigated in radical copolymerization with styrene (St) and methyl methacrylate (MMA). In copolymerization of TRFAm (M2) with St (M1), monomer reactivity ratios were determined to be r1 = 1.07 and r2 = 0.20 for St-TMFAm, and r1 = 1.88 and r2 = 0.11 for St-TEFAm, from which Q2 and e2 values were estimated to be 0.35 and 0.44 for TMFAm, and 0.19 and 0.47 for TEFAm, respectively. The other TRFAm were also copolymerized with St, but copolymerization with MMA gave polymers containing a small amount of TRFAm units. The polymer from TRFAm consists of a less-flexible poly(N,N-dialkylaminocarbonylmethylene) structure. The solubility and thermal property of the polymers were also investigated.
    Additional Material: 12 Ill.
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  • 111
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    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1725-1737 
    ISSN: 0887-624X
    Keywords: (heparin-PEO) grafted segmented polyurethaneurea ; surface modification ; nonthrombogenic surface ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new synthetic approach for the preparation of segmented polyurethaneurea (SPUU)-PEO-Heparin graft copolymers (B-PEO-Hep) has been developed. The procedure involved the coupling of hexamethylene diisocyanate (HMDI) to soluble Biomer® (B) through an allophanate/biuret reaction. The free isocyanate (NCO) groups attached to Biomer® were then coupled to PEO terminal hydroxyl groups to form PEO grafted Biomer® (B-PEO). B-PEO free hydroxy groups were modified with HMDI to introduce terminal isocyanate groups. The NCO functionalized B-PEO was then coupled to heparin (Hep) functional groups (—OH, —NH2) producing B-PEO-Hep graft copolymer. Synthetic intermediates were confirmed by FTIR, NCO group determination, and toluidine blue heparin assay. Physical characterization techniques, such as contact angle measurements, water swelling, light scattering measurements, and DSC thermal analysis, detailed properties of the graft copolymer containing covalently bound heparin. This new heparinized copolymer can be applied as a coating on other existing blood contacting surfaces without changing bulk properties. The heparin bioactivity observed attests to the usefulness of this new procedure as a coating to improve the blood compatibility of blood-contacting surfaces.
    Additional Material: 13 Ill.
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  • 112
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    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1779-1787 
    ISSN: 0887-624X
    Keywords: α-methyleneindane ; tacticities ; monomer reactivity ratios ; exo-methylene cyclic monomers ; depropagation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-Methyleniedane (MI), a cyclic analog of α-methylstyrene which does not undergo radical homopolymerization under standard conditions, was synthesized and subjected to radical, cationic, and anionic polymerizations. MI undergoes radical polymerization with α,α′-azobis(isobutyronitrile) in contrast to α-methylstyrene, owing to its reduced steric hindrance, though the polymerization is slow even in bulk. Cationic and anionic polymerization of MI with BF3OEt2 and n-butyllithium, respectively, proceed rapidly. The thermal degradation behavior of the polymer depends on the polymerization conditions. The anionic and radical polymers are heteortactic-rich. Reactivity ratios in bulk radical copolymerization on MI (M2) with methacrylate (MMA, M1) were determined at 60°C (r1 = 0.129 and r2 = 1.07). In order to clarify the copolymerization mechanism, radical copolymerization of MI with MMA was investigated in bulk at temperatures ranging from 50 to 80°C. The Mayo-Lewis equation has been found to be inadequate to describe the result due to depolymerization of MI sequences above 70°C.
    Additional Material: 8 Ill.
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  • 113
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1819-1824 
    ISSN: 0887-624X
    Keywords: side chain liquid crystalline polymer ; side-on mesogenic group ; MNDO-evaluation ; dipolar configuration ; polarizability tensor ; nonlinear electro-optical response ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 114
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1833-1833 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 115
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1835-1835 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 116
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    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1845-1851 
    ISSN: 0887-624X
    Keywords: sulfonium salt ; cationic initiator ; effect of substituent ; cationic polymerization ; glycidyl phenyl ether ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Benzyl o-, m-, and p-substituted phenyl methyl sulfonium salts (2b-2g) were synthesized and their activities as cationic initiators were evaluated in the bulk polymerization of phenyl glycidyl ether (PGE). Especially, their activities were estimated with respect to the effect of substituents on the aryl groups. In the polymerizations of PGE with a series of benzyl p-substituted phenyl methyl sulfonium salts, the order of their activities was found to be 2c (CH3OCOO) 〉 2b (CH3COO) 〉 2d (CH3O) ∼ 2a (HO). In particular, 2c was the most active initiator of all, capable of initiating the polymerization of PGE even at room temperature. In the polymerizations with 2a, 2e (m-Cl), 2f (o-CH3), and 2g (m-CH3), the activity of 2e was the highest of all while those of 2a, 2f, and 2g were almost the same. These results strongly suggested that the electron-withdrawing group placed on the aryl group undoubtedly enhanced the activity of the sulfonium salts as the cationic initiators.
    Additional Material: 5 Ill.
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  • 117
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1917-1924 
    ISSN: 0887-624X
    Keywords: polyimides ; cyclophane ; endcap ; 4-amino[2.21] para cyclophane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new family of addition curing polyimides were prepared that contained 4-amino [2.2]-paracyclophane as the endcap. An improved synthesis of the endcap 4-amino-[2.2] cyclophane was accomplished increasing the yield to 60% and simplifying the procedure. DSC and rheological analysis of endcapped polyimide oligomers confirmed that the onset for polymerization of the ethylene bridge was 250°C. 13C CP/MAS NMR was used to determine the structural changes of the oligomers after thermal treatment. The cyclophane capped polyimides were successfully compression molded to from void free neat resin specimens. T'gs as high as 353°C were obtained by thermomechanical analysis for postcured samples. Preliminary thermal stability studies (TGA) suggest that these resins have a high onset of decomposition ranging from 549 to 567°C.
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  • 118
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1941-1947 
    ISSN: 0887-624X
    Keywords: new synthetic method ; polyamide-benzoxazoles ; trimethylsilylated diaminophenol ; aromatic diacid chlorides ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic poly(o-hydroxy amide)s having inherent viscosities of 0.6-2.2 dL/g were readily synthesized by the low-temperature solution polycondensation of N,N′,O-tris(trimethylsilyl)-substituted 2,4-diaminophenol with aromatic dicarboxylic acid chlorides in various organic solvents. The viscosity values were much higher than those of the polymers obtained by a conventional method using parent 2,4-diaminophenol. Subsequent thermal cyclodehydration of the poly(o-hydroxy amide)s at 280°C under vacuum afforded the corresponding aromatic polyamide-benzoxazoles. Most of the poly(o-hydroxy amide)s dissolved readily in amide-type solvents, whereas the polyamide-benzoxazoles were quite insoluble in organic solvents. The polyamide-benzoxazoles, which gave yellow, transparent, and tough films, had glass transition temperatures of 260-300°C and were stable up to 400°C in air.
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  • 119
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1971-1976 
    ISSN: 0887-624X
    Keywords: butadiene sulfone ; poly(butadiene sulfone) ; ultrasonic vibration ; electroinitiation ; electropolymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electroinitiated polymerization of butadiene sulfone was achieved by direct electron transfer in acetonitrile - tetrabutylammonium fluoroborate system by controlled potential electrolysis technique. High conversions were obtained at reasonable temperatures and polymerization times. The polymer was found to be composed of linear segments along with some cyclic units. The effect of monomer concentration, temperature, and polymerization potential on the rate of polymerization was investigated. Temperature and polymerization potential have positive effects on the rate of polymerization. The effect of ultrasonic vibration was also investigated by conducting electrolyses at different monomer concentrations in the presence and absence of ultrasonic vibration. It was observed that the rate of polymerization increases significantly in the presence of ultrasonic vibration. The inverse relationship between the rate of polymerization and monomer concentration was observed in presence and absence of ultrasonic vibration.
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  • 120
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. i 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 121
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 29-37 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The monomer reactivity ratios for copolymerization of 2-vinyl-4,4-dimethylazlactone (VA) and ethyl α-hydroxymethylacrylate (EHMA) were 0.20-0.24 and 0.53-0.74, respectively, which show that EHMA is slightly more reactive with VA than with itself and should lead to random copolymers favoring alternation. The VA-styrene (VA-St) system also has a tendency to form random copolymers but with increased tendency for alternation with both r1 and r2 between 0.18-0.22. Tg's of VA-EHMA and VA-St copolymers varied between 100 and 136°C, and 96 and 117°C, respectively. Thermolysis of VA-EHMA copolymers resulted in crosslinking via the ring-opening reaction of VA groups by EHMA alcohols, followed by transesterification involving EHMA units at higher temperatures leading to highly crosslinked structures. The performed dimer of EHMA and VA was also synthesized and found to be an effective crosslinking agent in free radical vinyl polymerizations.
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  • 122
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 39-43 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New soluble polyimides with inherent viscosities of 0.2-0.6 dL/g were synthesized from 3,4-bis (4-aminophenyl)-2,5-diphenylfuran and various aromatic tetracarboxylic dianhydrides by the conventional two-step method which involved ring-opening polyaddition and subsequent cyclodehydration. Almost all of the polymides were generally soluble in a wide range of organic solvents such as N,N-dimethylacetamide, 1,3-dimethyl-2-imidazolidone, m-cresol, o-chlorophenol, and pyridine. The polyimide prepared from pyromellitic dianhydride was crystalline, whereas the other polyimides were amorphous. All the polyimides have glass transition temperatures in the range of 281-344°C and showed no appreciable weight loss up to 410°C in both air and nitrogen atmospheres.
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  • 123
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 93-100 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(2-methoxy-5-methylthio-1,4-phenylene vinylene), PMTPV, and copolymers containing both unsubstituted or 2,5-dimethoxy-substituted and 2-methoxy-5-methylthio-1,4-phenylene vinylene units were prepared in thin films from their water-soluble, sulfonium salt precursor polymers. Doping of drawn and undrawn films of PMTPV with I2 vapor led to conductivities of 10-4-10-3 S cm-1, which is significantly lower than those reported for poly(2,5-dimethoxy-1,4-phenylene vinylene). Conductivity of I2-doped copolymer films ranges from 10-3-100 S cm-1 depending on composition.
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  • 124
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 121-125 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 125
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    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 193-200 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High molecular weight alternating block copolymers of polyethesulphone (PES) and polydimethylsiloxane (PDMS) were prepared by the condensation of dimethylamino-terminated PDMS oligomers and hydroxy-terminated PES oligomers in 1,2-dichlorobenzene. Microphase separation of the block copolymers at exceptionally short block lengths was observed by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The Si—O—C intersegment linkage in these materials appeared to display poor hydrolytic stability which is contrary to results obtained for other block copolymers.
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  • 126
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 225-231 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied in detail the effects of synthesis conditions, such as current density and sodium dodecylsulfate electrolyte concentration, on the electrical and mechanical properties of polypyrrole. Flexible and self-supported films were electrochemically obtained using an aqueous solution containing pyrrole and sodium dodecylsulfate. The conductivity (2-20 S/cm) of the films increases with increases in either the current density or the electrolyte concentration. This behavior is caused by the structural changes induced by the different kinetics of film formation. Result indicate that the dodecylsulfate anion, incorporated as dopant in the polymer, randers it flexible with tensile strength in the order of MPa.
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  • 127
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 209-218 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of an epoxy prepolymer based on bisphenol A diglycidylether (DGEBA) with γ-aminopropyltriethoxysilane (γ-APS) are studied. The results of different techniques are compared: size exclusion chromatography, differential scanning calorimetry, chemical titration, and Fourier Transform Infrared absorption. Epoxy amine reactions are shown to be faster than the crosslinking reactions between alkoxysilane and hydroxy groups, and thus, can be studied seprately. The reactivity of the epoxy group in DGEBA is compared with that of phenylglycidylether (PGE). And the reactivity of the amine group of γ-APS is compared with that of hexylamine. The kinetic constants are calculated with a mechanism which takes into account both the catalytic and noncatalytic reactions. The ratio r = k2/k1 of the reactivity of the secondary to the primary amino-hydrogens was also determined. The values of r are 1.4 for hexylamine and 1.2 for γ-APS. The reactivity of the epoxy groups are the same for both PGE and DGEBA.
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  • 128
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 251-259 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of methacrylate esters of 4-cyanophenyl-(4-(ω-hydroxyalkyloxy)) cinnamates, with spacer lengths of 2 and 6 methylene units and the synthesis of the corresponding acrylate ester with a spacer of 2 methylene units are described. The methacrylate monomers were polymerized by free radical polymerization, both as homopolymers and as copolymers with the analogous benzoate monomer of spacer length 6. The acrylate ester could not be polymerized successfully under the same reaction conditions. Polymers were characterized by NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermo-optic observations. Of the monomers prepared, only the cinnamate with a hexamethylene spacer shows a mesophase, seen on supercooling of the melt. All of the polymers prepared were liquid crystalline, with smectic behavior predominating in the polymethacrylates with the longer spacer group. A narrow nematic region is seen just below the clearing temperature with a range of 3-9°C, nematic character is increased in the copolymer series with the degree of incorporation of the cinnamate monomer with the spacer group of length 2.
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  • 129
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 287-289 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 130
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 291-292 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 131
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 453-457 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel poly(amide-sulfonamide)s have been prepared by reacting terephthalic, isophthalic, and sebacic acid and their acid chlorides with variously substituted diamines containing preformed sulfonamide linkages utilizing solution polymerization techniques. Inherent viscosities of the prepared polymers varied from 0.22 to 1.21 dL/g. Those having inherent viscosities greater than 0.4 dL/g formed clear, tough, flexible films. Glass transition temperatures ranged from 87 to 273°C. Thermogravimetric analyses of the polymers showed moderate thermal stability.
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  • 132
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 515-523 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of 9-vinyl anthracene (VAn) on solution and emulsion polymerization of styrene are examined, to gain information about the mechanism of particle formation in emulsion polymerizations. Styrene solution polymerization in ethyl benzene is found to be inhibited by small amounts of VAn. In an emulsion system, the effects of VAn are found to depend on surfactant concentration [S]. With [S] = 0, addition of VAn engenders some inhibition and very little change in the steady-state polymerization rate. As [S] is increased from zero to above the critical micelle concentration (cmc), a slight increases in the induction period and an increasing retardation (reduction in the steady-state rate) are observed. Below the cmc, VAn has no significant effect on the particle number, but above the cmc it considerably increases the latter with concomitant appearance of very small (5-15 nm radius) particles. The data strongly support the supposition that the coagulative/homogeneous nucleation mechanism dominates particle formation for [S] below the cmc. Above the cmc, the data are compatible with both the micellar entry and coagulative/homogeneous mechanisms.
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  • 133
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modification of fluorine-containing polymers has recently received much attention due to new chemistries allowing for refunctionalization of these materials, especially their surfaces. In this article results are discussed which demonstrate various interesting modifications (including incorporations of —OH and oxygen comprised functionality) to expanded poly(tetrafluoroethylene) (ePTFE) surfaces. This is effected through the use of low damage, radio frequency glow discharge (RFGD) processes. The low damage conditions, which preserve the original pore structure/morphology of these RFGD treated materials, are supported by Scanning Electron Microscopy (SEM) while the resulting atomic and molecular effects are investigated through other surface analytical methodology. All materials reported in this investigation have been subjected to intensive structural analyses utilizing Electron Spectroscopy for Chemical Analysis (ESCA), Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), and wettability profiles obtained through contact angle measurements using a large series of liquids having varying surface tensions and surface reactive functionality. Through this multitechnique analysis of both expanded PTFE and poly(vinylidene fluoride) (PVDF) treated surfaces, a model is supported which illustrates surfaces possessing both high and low energy regions comprising both oxygen and fluorine functionality in close molecular proximity.
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  • 134
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 607-610 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 135
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 637-642 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propagating radicals of dialkyl fumarates (DRFs) and deuterated fumarate were trapped by admitting a 2-methyl-2-introsopropane (BNO) solution to the polymerization mixture containing the active radicals or by the polymerizations initiated with di-t-butyl hyponitrite in the presence of BNO. Although ESR spectra of the propagating radicals were appreciably changed with the size of the ester alkyl groups, all the nitroxyl radicals resulting from the spin trapping exhibited similar six-line spectra. The hyperfine splitting constant for the α-hydrogen of the radical moiety showed a slight dependence on the chain length, and the bulkiness of the ester alkyl group did not affect splitting of the spectra. These findings indicate that a substituted methylene radical is produced by addition of the primary radical to DRF followed by propagation throughout the polymerization and that poly(DRF) radical does not encounter severe hindrance in the reaction with BNO.
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  • 136
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 671-676 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A polymer bearing pendant norbornadiene (NBD) moieties and a low molecular weight model compound ([2-carbobenzyloxy-3-phenyl-2,5-norbornadiene CBPNB)], were synthesized by substitution reaction of poly(p-chloromethylstyrene) and benzyl chloride, respectively, with the potassium salt of 3-phenyl-2,5-norbornadiene-2-carboxylic acid. Photochemical valence isomerization and storage stabilities of the resulting polymer having corresponding pendant quadricyclane (QC) groups and the low molecular weight QC compound were investigated in dichloromethane solution. It was found that the rate of photochemical valence isomerization of the pendant NBD moiety in the polymer was the same as or slightly higher than that of CBPNB, and the storage stability of the QC group in the polymer was higher than that of the QC compound resulting from CBPNB in the solution. The photochemical reaction of the pendant NBD moiety within the polymer without catalyst proceeded quantitatively in the film state. However, the photochemical reaction of the polymer films blended with 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt (II) catalyst (Co-TPP) did not proceed quantitatively, and the degree of conversion of the pendant NBD moiety in the polymer decreased with increasing amounts of Co-TPP in the film. The QC group produced in the polymer by photo-irradiation had excellent storage stability in the film state without Co-TPP. On the other hand, the QC group in the polymer films blended with Co-TPP Catalyst reverted gradually to the NBD group at room temperature.
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  • 137
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 547-553 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyisobutylene-co-isoprene (PIBI) can be epoxidized with hydrogen peroxide in the presence of methyltrioctylammonium tetrakis (diperoxotungsto) phosphate(3-) as the catalyst in a biphasic system. The effects of the reaction time and temperature, the ratio of the organic phase to the aqueous phase, the concentration of the catalyst and polymer and stirring intensity, respectively, are studied on the conversion of double bonds to oxirane groups. 1H-NMR analysis confirms the absence of ring opening side reactions in this epoxidation reaction system. The kinetics of the reaction are discussed. The rate constants are measured at four temperatures and the activation energy for the reaction is determined as 54.2kJ/mol. The optimum reaction temperature is about 60°C.
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  • 138
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 585-589 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 139
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 599-602 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 140
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 685-696 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The evolution of the photochemical degradation of ABS has been studied in conditions of long wavelength irradiation (λ's〉 300 nm). The main photoproducts involved in the oxidative evolution have been identified by using FTIR spectroscopy and chemical titrations. A particular attention has been devoted to α-β unsaturated ketones that appear as secondary photoproducts. Those ketones present a low photochemical stability when exposed in the range 300-400 nm. Conditions for their formation have been experimentally studied. Formation of oxidation photoproducts has been also studied at the macroscopic level and it has been shown that their repartition in the polymer is heterogeneous. The origins of the heterogenities have been studied.
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  • 141
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 719-727 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The scope of polyformal formation from nitro- and fluorodiols has been explored further with a series of α, ω-diols. Polymers with M̄ns of 2000-4000 were generally obtained but M̄ns approaching 10,000 are possible in some cases. Effects of monomer structure and reaction parameters on polymer molecular weight are described. The polymers were characterized by GPC, 1H-NMR, and DSC analysis.
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  • 142
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 749-758 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new acetylene-terminated Schiff base monomer, N,N′-(1,4-phenylenedimethylidyne)-bis-(4-ethynylaniline) (PPP), was synthesized and was characterized by nuclear magnetic resonance and infrared spectroscopy. This monomer was then polymerized to yield a new polymer (PPPP) with alternating units of aromatic imine and diacetylene via an oxidative coupling polymerization of the acetylenic terminal groups. The monomer was also polymerized by thermal curing at elevated temperatures up to 400°C to afford a crosslinked polymer network without significant structural decomposition. Thermal properties and thermal reactions of the monomer and the polymers were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymers exhibit excellent thermal stabilities in an inert atmosphere. Electronic properties of the polymers are also discussed.
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  • 143
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 781-784 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 144
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 807-812 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomer-isomerization polymerization of cis-2-butene (c2B) with Ziegler-Natta catalysts was studied to find a highly active catalyst. Among the transition metals [TiCl3, TiCl4, VCl3, VOCl3, and V (acac)3] and alkylauminums used, TiCl3—R3Al (R = C2H5 and i-C4H9) was found to show a high-activity for monomer-isomerization polymerization of c2B. The polymer yield was low with TiCl4—(C2H5)3Al catalyst. However, when NiCl2 was added to this catalyst, the polymer yield increased. With TiCl3—(C2H5)3Al catalyst, the effect of the Al/Ti molar ratio was observed and a maximum for the polymer yields was obtained at molar ratios of 2.0-3.0, but the isomerization increased as a function of Al/Ti molar ratio. The valence state of titanium on active sites for isomerization and polymerization is discussed.
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  • 145
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1015-1021 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of copolymers containing triad ester mesogenic units, with pendent n-octyl substituents, and triad ester nonmesogenic units, both with flexible spacer groups, was prepared and characterized for the effect of the nonmesogenic unit content on transition temperatures and thermodynamic parameters. The mesophase temperature range increased, but temperature, enthalpy, and entropy of isotropization decreased in a linear manner with increasing nonmesogen comonomer content. The entropy of isotropization is considered to be a quantitative measure of the degree of order of the nematic phase, but this order may include both the amount and the order parameter of the mesophase if, as proposed, both the isotropic and nematic phase exist below the isotropization temperatures of the copolymers.
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  • 146
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1045-1052 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a novel bisphenol, 9,9-bis(3,5-diphenyl-4-hydroxyphenyl)fluorene, in high yield by the transalkylation of 9,9-bis(4-hydroxyphenyl)fluorene is described. Three poly(arylene ether)s based on this hindered phenol were prepared with molecular weights (Mn) ranging from 34 800 to 51 300 and inherent viscosities ranging from 0.27 to 0.43 dL/g. The polymers have Tg's of 236-262°C and did not lose weight below 350°C, with 10% weight loss recorded above 550°C. They are readily soluble in chlorinated solvents such as methylene chloride, chloroform, and 1,2-dichloroethane at room temperature. Attempts to synthesize an analogous monomer, bis (3,5-diphenyl-4-hydroxyphenyl)diphenylmethane, are described.
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  • 147
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 495-503 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High strength alumina fibers were fabricated with a polymer precursor process which was monitored with 13C-NMR, elemental analysis, gas evolution, SEM, and X-ray diffraction. Methylaluminoxane was chain extended by reaction with H2O, the unreacted methyl groups were converted to propanoyloxyl and i-propanoyl groups in molar ratios of 0.2 : 0.8 to 0.4 : 0.6 to afford spinning dope of adequate fluidity which can be spun into filaments with suitable stability. These precursor fibers were hydrolyzed in two stages at ambient temperatures and at 320-350°C, and then calcined at 950°C. The resulting alumina fibers have average tensile strengths up to 1.1 GPa and modulus of greater than 140 GPa.
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  • 148
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent work in our laboratories has fully characterized the surface region of a segmented poly(ether-urethane) (PEU) extending from the air/polymer interfacial region through bulk depths in the micron range. This characterization utilized energy and angle dependent Electron Spectroscopy for Chemical Analysis (ESCA), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and Comprehensive Wettability Profiling (contact angle using a homologous series of liquids) as defined by Zisman. In this study this same multi-analytical-technique approach is used to elucidate changes in these PEU surfaces induced through an H2O Radio Frequency Glow Discharge (RFGD) plasma. This investigation reports both qualitative and quantitative changes due to the modification treatments as well as the permanency of the changes effected on these surfaces through the plasma treatment. From our analyses, the amount of surface residing polyurethane (hard segment) is observed to increase due to a proposed plasma etching mechanism. Further, the addition of oxygen containing functionality is detected at the modified surfaces unique with respect to the unmodified PEU. These surface modifications which show large increases in wettability, are finally observed to be semi-permanent over a time period of 6 months.
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  • 149
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1379-1385 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrrole (PY) and 2,2′-bithiophene (BT) have been electropolymerized at various feed ratios in LiClO4/Propylene carbonate (PC) and the mer ratios in the copolymer determined by N and S. microanalysis. A strong correlation was observed between the copolymer compositions and the monomer feed ratios using the copolymer equation, and reactivity ratios were determined by a nonlinear error-in-variables approach. Although PY predominates in these copolymers, the proportion of BT increases with increasing applied potential. It is shown that reactivity ratios do not have to be understood in the traditional sense, but may be simply a measure of the relative ease of oxidation of the monomers at the electrode.
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1439-1446 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes of boron trichloride, boron tribromide, and ethylaluminumdichloride with various acetates were directly observed by 1H-NMR. Complexes of secondary and tertiary acetates which model macromolecular active species in polymerization of styrene and isobutene are stable at -75°C, but decompose at temperatures above -30°C to yield corresponding chlorides or bromides. The stability of complexes depends on the Lewis acid, the alkyl group in the ester, and the structure of acetate. Rates of the bimolecular exchange of complexes with excess acetate were calculated from dynamic NMR to be kex = 2 × 101 L mol-1 s-1 (-65°C) and kex = 5 × 104 L mol-1 s-1 (-75°C) for 1-phenylethyl acetate with BCl3 and EtAlCl2, respectively.
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  • 151
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1475-1482 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Styrene oxide (SO) (phenyl oxirane) and 1,2-cyclohexene oxide (CO) (7-oxa bicyclo[410] heptane) have been copolymerized neat with the aid of the carbocation salt triphenylmethyl hexachloroantimonate (Ph3CSbCl6) (HC) at 0, 30, and 56°C. NMR spectra of the polymeric products before and after extraction with acetone indicated that the copolymerization products were copolymers and not mixtures of the respective homopolymers. Both, the Kelen-Tüdos and Fineman-Ross methods for the determination of the monomer reactivity ratios yielded identical results. These were: 0°C: r1 (CO) = 4.34, r2(SO) = 0.34; 30°C, r1(CO) = 4.19, r2(SO) = 0.42; 56°C, r2(CO) = 3.94, r2(SO) = 0.46.
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  • 152
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1561-1574 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymers were synthesized from substituted phenolic and aromatic amine compounds with hydrogen peroxide as the source of an oxidizing agent and horseradish peroxidase enzyme as the catalyst. The polymerization reaction was carried out in a monophasic organic solvent with small amounts of water at room temperature. Conditions for the synthesis of polymers with respect to reaction time and yield were studied with a number of monomers at different concentrations and in solvents with different buffers with pH range of 5.0-7.5. Physical and chemical properties of these homo-and copolymers were determined with respect to melting point, solubility, elemental analysis, molecular weight distribution, infrared absorption (including FTIR), solid-state 13C nuclear magnetic resonance, thermal gravimetric analysis, and differential scanning calorimetry. The enzyme catalyzed reactions produced polymers of molecular weight greater than 400,000 which were further fractionated by differential solubility in solvent mixtures and the molecular weight distribution of the polymer fractions were determined. In general, the polymers synthesized have low solubilities, high melting points, and some degree of branching.
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1603-1607 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Supported catalyst for fluidized bed polymerization processes has been prepared by reacting macroporous SiO2 first with MAO (methylaluminoxane) and then with Et [Ind]2ZrCl2. It contains 0.60 wt % of Zr and an [Al]/[Zr] ratio of 50. This catalyst produces homogeneous E/P (ethylene/propylene) copolymers with truly random copolymerization behaviors and required to achieve the same copolymerization activity for the Et[Ind]2ZrCl2/MAO would be required a total [Al]/[Zr] of only 670. Several time larger amount of MAO would be required to achieve the same copolymerization activity for the Et [Ind]2ZrCl2/MAO catalyst in solution. This random copolymerization is independent of catalyst concentration and composition. Activation of the supported catalyst with i-butylaluminoxane, tri-i-butylaluminum, or trimethylaluminum resulted in lower activity and copolymers having high ethylene content and crystallinity.
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  • 154
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1633-1638 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The serendipitous formation of 2,5-dimethoxy- 1,4-benzoquinone is reported from the reaction of 1,4-benzoquinone with methanol, DABCO, and paraformaldehyde. This monomer, and its di-n-butoxy analog, are also available from 2,5-dihydroxy-1,4-benzoquinone. These materials are capable of novel polycondensation reactions with diamines such as 1,6-hex-anediamine. Use of m-crexsol as polymerization solvent gave a dark, insoluble product while various amide solvents lead to orange or pink polymers that had average degrees of polymerization from 5 up to 〉30. These polymers, Plus model compounds obtained from 1-aminopropane and N,N'- dimethyl-1,6-hexanediamine, were characterized by FTIR, solution, and solid-state NMR.
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  • 155
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1639-1644 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of allyl ethers in coating resins have been studied in relations to different systems. The details that have been investigated are: the reactions between allyl ethers-styrene-cobalt salt in air, the influence of cobalt salt on oxidized allyl ethers, and the interaction between allyl ethers and maleic esters with respect to copolymerization. The curing rates of allyl functional oligomers as coatings have also been studied. The results are summarized together with the results from a previous article by the same authors to give an overall view of the curing mechanism in allyl ether functional unsaturated polyester resins dissolved in styrene.
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  • 156
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1661-1666 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of oil-soluble radical generators for emulsion polymerization is considered. When radicals are formed in pairs within particles of a seed latex, the occurrence of radical desorption leads to complex kinetics. Use of radical balances and realistic simplifications produce a method for a relatively simple calculation of radical populations in the particles. Examples are restricted, for illustration purposes, to cases where the average number of radicals per particle, n, is less than one. Very low rates of radical desorption cause a substantial increase in n. As the desorption rate increases, the value of n decreases. n increases slowly with radical generation rate. Large decreases in the chain termination rate coefficient (which may accompany a gel effect) can have a negligible effect on the value of n. Radical distributions obtained from oil-soluble initiators can be slightly broader than those expected from the use of water-soluble initiators. The kinetics of emulsion polymerization will be similar for the two types of radical generator when radicals from oil-soluble generators can desorb from the polymer particles.
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  • 157
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1681-1689 
    ISSN: 0887-624X
    Keywords: siloxane ; silicon polycarbonate copolymer ; polycarbonate ; interfacial ; 4,4′-isopropylidenediphenol ; BPA ; aryl-terminated siloxane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several synthetic routes to silicon polycarbonate copolymers utilizing aryl-terminated siloxanes have been examined. Anhydride capped siloxanes with varying polydimethylsiloxane units were prepared by the acid equilibration of 1,3-bis(4,4′-phthalicanhydride)tetramethyldisiloxane. These siloxanes were then imidized with aminophenol to the corresponding phenol capped siloxane. Reaction of these materials with 4,4′-isopropylidenediphenol (BPA) and phosgene (interfacially and non-interfacially) produced silicone polycarbonate copolymers. Similar copolymers were obtained by reaction with bis-chloroformate derivatives of 4,4′-isopropylidenediphenol (monomer and oligomers). The different synthetic routes significantly affect the thermal and mechanical properties as well as the composition of the new polymers. Materials synthesized by the bis-chloroformate route exhibit good hydrolytic and melt stabilities. Those made interfacially underwent phase separation in the melt.
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  • 158
    ISSN: 0887-624X
    Keywords: new synthetic method ; vapor deposition polymerization ; ultrathin polyimide films ; N-trimethylsilylated aromatic diamines ; aromatic tetracarboxylic dithioanhydride ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel method for the preparation of ultrathin films of aromatic polyimides was developed through vapor deposition polymerization from combinations of monomer pairs of either N,N′-bis (trimethylsilyl)-substituted aromatic diamines and pyromellitic dianhydride or aromatic diamines and pyromellitic dithioanhydride. Both diamine component and tetracarboxylic dianhydride component were evaporated simultaneously at a stoichiometric molar ratio under vacuum, giving a deposited film on a substrate, which consisted of a polyamic acid derivative formed by the ring-opening polyaddition. The deposit was then converted to polyimide by thermal imidization at a relatively lower temperature, compared with a conventional method using the parent diamine and tetracarboxylic dianhydride. The properties of polyimide ultrathin films such as thermal stability, chemical resistance, and dielectric behavior were almost the same as those of the polyimide films prepared by a conventional method.
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  • 159
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1759-1777 
    ISSN: 0887-624X
    Keywords: copolymerization ; network ; bioabsorbable ; caprolactone ; valerolactone ; polyurethane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Difunctional hydroxy-terminated poly(ε-caprolactone-co-ε-valerolactone) (PCV) oligomers were synthesized by the diol-initiated bulk copolymerization of ε-caprolactone (C) and δ-valerolactone (V). The two homopolymers were semicrystalline, with almost identical melting temperatures; copolymerization significantly lowered the melting point (Tm) compared to either homopolymer. Copolymer melting points were found to decrease with decreasing molecular weight and to be dependent on composition, i.e., the incorporation of a comonomer into either homopolymer resulted in a decrease in Tm, with the maximum decrease occurring at a copolymer composition of about 60 mol % ε-caprolactone. The molar compositions of the copolyesters were determined from 13C-NMR spectra. The reactivity ratios of the two monomers (M1 = C, M2 = V) were determined to the r1 = 0.25 and r2 = 0.49. Number average molecular weight (M̄n) of the PCV diols was inversely proportional to the initial diol concentration within the studied molecular weight range of 900 to 11,100 g/mol. Crosslinked polyurethane networks were prepared by reacting PCV diols with triphenylmethane triisocyanate. Network characterization included determination of sol content by solvent extraction, glass transition (Tg) and Tm by DSC, and tensile properties by stress-strain measurements. Completely amorphous networks resulted from PCV diols of M̄n ≤ 2,400; semicrystalline networks resulted from PCV diols of M̄n ≥ 3,600.
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  • 160
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1223-1223 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 161
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1807-1817 
    ISSN: 0887-624X
    Keywords: VCl3 ; propylene polymerization ; Ziegler-Natta catalyst ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvay type S-VCl3 catalyst has 7% of catalytically active vanadium sites ([C*]) with kp (rate constant of propagation) = 31 (M s)-1 for ethylene polymerization. Addition of a comonomer, propylene of 4-methylpentene-1 (4-MP) significantly raised the ethylene polymerization activity. S-VCI3 catalyst has very small amounts of catalytically active vanadium for propylene polymerizations: [Ci*] = 0.19% with kp,i = 857 (M s)-1 and [Ca*] = 0.45% with kp,a = 23 (M s)-1 for isospecific and nonspecific sites, respectively. Addition of a conomer, ethylene or 4-MP. lowered the propylene polymerization activity. S-VCI3 is more easily reduced to the divalent ion by AIR3 than S-TiCl3. Methyl-p-toluate moderates the reducting power of AIR3; it increase the productivity and stereoselectivity of the S-YiCl3 catalyst, VCI3 supported on MgCl2 (CW-V catalyst) has enhanced rate constant of propylene polymerization but has the opposite effects on the S-TiCl3 Catalyst. VCI3 supported on MgCl2 (CW-V catalyst) has enhances rate constant of propylene polymerization but only a minute fraction of the supported vanadiums are catalytically active: [Ci*] = 0.019% and kp,i = 1580 (Ms)-1, [Ca*] = 0.057% and kp,i = 58 (M s)-1. This is compared with far greater number of catalytically active titanium sites in the TiCl3 supported on MgCl2 catalyst: [Ci*] = 6% and kp,i = 200 (M s)-1, [Ca*] = 6% and kp,a = 16(M s)-1. Therefore, both the S-VCI3 and CW-V catalysts are highly stereoselective but low in efficiency with respect to the utilization of the vanadium ion in the catalysis.
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  • 162
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and optical resolution of α-phenyl β-amino-ethylpropionate led to the preparation of optically active α-phenyl β-propiolactones (PhPL) of different optical purities. The enantiomeric excess of PhPL was determined using 200 MHz 1H-NMR spectroscopy, after complexation with tris[3-(trifluoromethyl hydroxymethylene)-d-camphorato]europium III. It was then polymerized, in bulk and in solution, using a potassium acetate/crown ether complex as initiator. The optically active poly(PhPL)s thus obtained are insoluble in most organic solvents, whereas atactic poly(PhPL)s are soluble in CCl4, CHCl3, and dichloroethane. Several differences are observed between the physical properties of optically active and atactic poly(PhPL)s. However, atactic poly(PhPL)s are semi-crystalline polymers, similar to poly(α-disubstituted β-propiolactone)s, but in contrast with poly(α-methyl β-propiolactone). Melting (Tf) and glass transition temperatures, as well as enthalpy of fusion (ΔH), vary with the optical purity of the polymers. For example, atactic poly(PhPL) exhibits a Tf = 94°C and ΔH = 9 J/g as compared to Tf = 119°C and ΔH = 37 J/g for a poly(PhPL) having an enatiomeric excess of 50%.
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  • 163
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1865-1873 
    ISSN: 0887-624X
    Keywords: azobenzene ; polyacrylates ; liquid crystals ; photoresponsive polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization are reported of two new series of structurally isomeric polyacrylates containing the azobenzene moiety spaced away from the backbone by a hexamethylene spacer and substituted in 4-position with linear alkoxy groups (C1—C6, C10) and with a lateral methyl group in 2′- or 3′-position. Thermal optical and X-ray analyses of the prepared polymer samples, with molecular weight ranging from 50 × 103 to 35 × 104 Dalton (M̄w/M̄n = 2-3), provide evidences for the establishment of liquid crystalline behavior in the melt in a fairly broad range of temperature. In any case, quenching from the mesophase allows for the lock-in of the liquid crystalline structure in the glassy state. The presence of the lateral methyl-substitutents causes a drop as high as 50-100 K. in the stability of the mesophase with respect to the corresponding samples of the methyl-unsubstituted series. A parallel depletion of the smectogenic character is also observed. Typical even-odd effects on the isotropization temperature and relevant thermodynamic parameters have been detected along with the formation of interdigitated smectic structures.
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  • 164
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1895-1902 
    ISSN: 0887-624X
    Keywords: N-(2-hydroxypropyl) methacrylamide copolymers ; bioadhesive polymers ; fucose containing macromolecules ; fucose recognition ; colon specific polymer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new route for the synthesis of bioadhesive water soluble polymeric drug carriers has been developed. Novel monomers, namely, N-methacryloylglycylglycylgalactosamine (MA-Gly-Gly-GalN) [8], MA-Gly-Gly-FucN [9], MA-Gly-Gly-GlcN [10], and MA-Gly-Gly-ManN [11], and copolymers [12-16] based on N-(2-hydroxypropyl) methacrylamide (HPMA) containing different content of pendant saccharide moieties (galactosamine, fucosylamine, glucosamine, or mannosamine), were synthesized. Copolymerization parameters for the copolymerization of HPMA [M1] and MA-Gly-Gly-GalN [M2] have been determined (r1 = 0.82, r2 = 0.38). Bioadhesion studies with everted sacs of guinesa pig small intestine and colon in vitro demonstrated that HPMA copolymers containing side-chains terminated in fucosylamine bind selectively to the colonic tissue. The extent of binding was dependent on the fucosylamine content of copolymers.
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  • 165
    ISSN: 0887-624X
    Keywords: living polymerization ; cationic polymerization ; vinyl ether ; trimethylsilyl halide ; zinc halide ; polymerization initiator ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trimethylsilyl halides (Me3SiY), in conjunction with zinc halides (ZnX2) (Y and X:I, Br, Cl), were employed to investigate the living cationic polymerization of isobutyl vinyl ether (IBVE) in toluene at -15°C in the presence of p-methoxybenzaldehyde; with the aldehyde and IBVE monomer, Me3SiY yields an initiating species [Me3Si—O—CHC6H4(OMe) —CH2CH(OiBu) —Y] that triggers the IBVE polymerization via the activation of its carbon-halogen bond (C—Y) by ZnX2 into Cδ+…Yδ-…ZnX2. Living polymerizations occurred with the silyl iodide and bromide irrespective of the type of ZnX2, either when Y = X (Me3Sil/Znl2 and Me3SiBr/ZnBr2) or when Y ≠ X (Me3Sil/ZnBr2, Me3SiI/ZnCl2, and Me3SiBr/Znl2). With these five initiating systems, the number-average molecular weights (M̄n) of the polymers increased in proportion to monomer conversion, and the molecular weight distributions (MWDs) of the polymers were narrow (M̄w/M̄n = 1.1-1.2). The Me3SiCl-based systems (Me3SiCl/ZnCl2 and Me3SiCl/Znl2), in (Me3SiCl/Znl2), in contrast, failed to give perfectly living polymerization; the M̄n indeed increased with conversion, but the MWDs of the polymers were broader (M̄w/M̄n = 1.3-1.5). Thus, the living nature of the polymerizations with Me3SiY/Znx2 is primarily determined by the halogen Y in Me3SiY, which generates the terminal carbon-halogen bond (C—Y) that is activated by ZnX2 for the propagation via a species Cδ+…Yδ-…ZnX2. For Y-, not only the iodide but the bromide anion also is suited for living cationic polymerization. The virtual absence of the effects of X in ZnX2 implies that the halogen exchange between ZnX2 and Y from Me3 SiY at the growing end (Cλ+…Yδ-…ZnX2 ⇄Cδ+…Xδ-…ZnXY) is absent or negligible.
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  • 166
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1955-1961 
    ISSN: 0887-624X
    Keywords: photoinitiation ; alkylaminobenzophenones ; radical efficiencies ; photopolymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behavior of the nonconjugated aminated benzophenones - 4-[2′-N,N-(diethylamino)ethoxy]benzophenone (E4), 2-[2′-N,N-(diethylamino)ethoxy]-4-methoxybenzophenone (E2), and 4-N,N-dimethylaminomethylbenzophenone (DM) - as photoinitiators of MMA polymerization has been studied and the results compared with those obtained with the conjugated aminobenzophenone 4-N,N-dimethylamino-4′-isopropyl-benzophenone (CU - MI). Photoreduction behavior of these compounds in various solvents in the presence and absence of MMA has been also examined. The order of the polymerization reaction with respect to monomer and initiator concentrations has been investigated; values of initiation quantum yield (Φi), Kp/K1/2t and efficiencies of the different radicals have also been determined. Similar polymerization rates (Rp) of methyl methacrylate (MMA) were found when E4 and CU-MI were used as photoinitiators under the same range of absorbed irradiation intensity. This fact results from a compensation between the higher rate of E4 radical production (n-π* transition type) and the greater reactivity of the radicals generated from CU-MI.
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  • 167
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1977-1986 
    ISSN: 0887-624X
    Keywords: reactivity of isocyanate group ; IPDI ; H12 MDI ; urethane ; alkoxy-silane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the reactions in bulk of 4,4′-dicyclohexyl methane diisocyanate (H12 MDI) and 5-isocyanato-1,3,3-trimethylcyclohexylmethyl isocyanate or isophorone diisocyanate (IPDI) with benzylic alcohol (BZA) and α-hydroxy-ω-methyl ether-terminated polyethylene oxide PEO (M̄w = 350) were studied by size exclusion chromatography (SEC) and 13C nuclear magnetic resonance (13C-NMR). The substitution effect is exhibited in the case of H12 MDI reactivity. The kinetic constants were calculated by a numerical method. The second-order kinetic mechanism was shown to be valid. In the IPDI case, the cycloaliphatic isocyanate group is shown to be more reactive than the aliphatic group in our conditions, without catalysis, in agreement with previous results from the literature, in our obtained by 1H-and 13C-NMR without any catalyst. The reactivity ratio is found to be on the order of 3. This difference in reactivity of the two isocyanate groups is used for the control synthesis of isocyanate and alkoxy-silane-terminated macromers.
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  • 168
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1549-1559 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The monomer addition policies required to produce homogeneous methyl methacrylateethyl acrylate copolymers of different compositions were determined by means of a semiempirical approach. This approach is useful for systems about which only a limited information is available. Applying this method only three reactions were needed to obtain homogeneous copolymers in a minimum process time. Comparisons were made between the results obtained using this monomer addition strategy and those from copolymerizations carried out under the classical starved conditions.
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  • 169
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1739-1749 
    ISSN: 0887-624X
    Keywords: photochemistry ; macromolecule metal complexes ; chromium (III) polymer systems ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymer coordinated chromium(III) complexes [Cr(bpy)2(PAA)2]+, 1, [Cr(bpy)2-(PMA)2]+, 2, [Cr(phen)2(PAA)2]+, 3, and [Cr(phen)2(PMA)2]+, 4, [where bpy, phen, PAA and PMA are, respectively, 2,2′-bipyridine, 1,10-phenanthroline, poly(acrylic acid), and poly(methacrylic acid)] were synthesized. The polymer-chromium(III) complexes were characterized by elemental and spectroscopic analyses. Thermal substitution reactions of these macromolecular chromium(III) complexes in basic solutions lead to the replacement of the polypyridyl ligand by hydroxide ion while in strong acidic solutions the polymer complexes precipitate out. The photochemical reactions are qualitatively similar to that of the thermal reactions and the quantum yields are dependant on the pH of the medium. Further, lower quantum yields were observed for the aquation of the polymer complexes in comparison with the monomeric chromium(III) complexes and the results are discussed in terms of the effect of the polymer environment. Flash photolysis of 1 and 3 results in the formation of transients with maxima at 480 nm for 1 and 470 nm, 580 nm for 3. The decay of the transients were found to obey first order kinetics and the rate constants were determined. The transients were suggested to be the alkyl-chromium complexes. Flash photolysis of 2 and 4 does not produce transients which is interpreted to be due to the presence of a methyl group in the ligand which hinders the formation of the carbonchromium bond.
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  • 170
    ISSN: 0887-624X
    Keywords: cation-radical polymerization ; aromatic polyethers ; Scholl reaction ; polymerization mechanism ; polymerizability ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article describes the synthesis and the cation-radical polymerization (Scholl reaction) of 1,3-bis[4-(1-naphthoxy) benzoyl] benzene (6) and 1,4-bis[4-(1-naphthoxy) benzoyl]- benzene (7) initiated by FeCI3. This polymerization produced poly(ether ether ketone ketone)s (PEEKK) of number average molecular weight (M̄n) up to 5400 g/mol. The synthesis of bis[4-(1-naphthoxy) phenyl] methane (8), 1,3-bis[4-(1-napthoxy) phenylmethyl] benzene (9), and 1,4-bis[4-(1-naphthoxy) phenylmethyl] benzene (10) are also described. Polyethers of M̄n up to 15400 g/mol at a FeCl3/monomer molar ratio of 2/1 were obtained. An increased polymerizability of the monomers 9 and 10 containing two CH2 groups versus that of the corresponding monomers containing two carbonyl groups (6 and 7) was observed. This enhanced polymerizability was explained based on the increased nucleophilicity of monomers 9 and 10.
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1837-1843 
    ISSN: 0887-624X
    Keywords: radical polymerization ; radical copolymerization ; α-alkylacrylic acid ; steric effect ; 1,1-disubstituted ethylene ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-Alkylacrylic acids (RAA's) bearing n-alkyl groups were found to homopolymerize with slower rates than acrylic and methacrylic acids to number-average molecular, weight (M̄n) of 104 or above. When the α-substituent was a branched alkyl group, the polymerization rate and M̄n decreased further. Reactivities of RAA's in copolymerization were interpreted by steric and resonance effects of the alkyl group using Hancock's steric substituent constant. Comparison of the reactivities of RAA's with those of methyl α-alkylacrylates revealed that replacement with the smaller carboxyl group facilitates polymerization and copolymerization. Preference of co-syndiotactic propagation in the copolymerization of methacrylic acid with styrene changed to random fashion in the copolymerization of the α-higher alkyl derivatives. After methylation with diazomethane, the homopolymers were shown to be thermally less stable than poly(methyl methacrylate). Tg's of poly(methyl α-ethylacrylate) and poly(methyl α-n-propylacrylate) were 57 and 25°C, respectively.
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1903-1908 
    ISSN: 0887-624X
    Keywords: thermal degradation mechanism ; liquid crystalline aromatic polyester ; pyrolysis-gas chromatography ; mass spectrometry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal degradation mechanisms of liquid crystalline aromatic polyesters (LCPs) prepared from p-hydroxybenzoic acid (PHB), biphenol (BP), and terephthalic acid (TA) were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The LCP containing deuterated terephthalate units and the LCPs that have different comonomer ratios were examined. On the basis of the pyrolysis products determined, the origin of the main pyrolysis products (benzene, phenol, biphenyl, phenyl benzoate, etc.) from the corresponding comonomer units were estimated and their thermal degradation mechanisms were eventually discussed in detail.
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 261-267 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel epoxy resins of various thiocarbonohydrazones have been synthesized by reacting the aldehyde or ketone derivatives of thiocarbohydrazide with excess of epichlorohydrin. The resins have been characterized by elemental analyses, epoxy equivalents, 1H-NMR and IR spectra, thermal analyses, and viscosity measurements. Curing of the resins has been carried out by mixing with thiocarbohydrazide or ethylenediamine and heating at 80°C for 48 h. A comparison of the thermal stability of the cured resin samples has been made.
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  • 174
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 281-286 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinyl monomers having electron acceptor groups such as nitroethylene, acrylonitrile, and acrolein were polymerized by KO2-charge transfer agent initiator systems in dimethylsulfoxide (DMSO) at 25°C. The new initiator systems were found to be stable for almost 1 month under nitrogen atmosphere. The initial rate of polymerization was so fast that both conversion and molecular weight of the polymers obtained were high. Especially their molecular weight distribution was observed to be very narrow by means of gel permeation chromatography (GPC). The anion radicals generated by one electron transfer from potassium superoxide (KO2) to charge transfer agents such as naphthalene, benzoquinone, azobenzene, etc., were suitable as initiator for the anionic polymerization of electron acceptor monomers. Study on block copolymerization of nitroethylene with acrylonitrile or acrolein was also attempted.
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  • 175
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 293-293 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 176
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and living cationic polymerization of 11-[(4-cyano-4′-biphenyl)oxy]-undecanyl vinyl ether (6-11) are described. The mesomorphic phase behavior of poly(6-11) with different degrees of polymerization was compared to that of 6-11 and of 11-[(4-cyano-4′-biphenyl) oxy] undecanyl ethyl ether (8-11) which is the model compound of the monomeric structural unit of poly(6-11). 6-11 displays a monotropic SA and a monotropic nematic mesophase while 8-11 an enantiotropic SA mesophase. Poly(6-11) with low degrees of polymerization exhibits an enantiotropic SA mesophase. Poly(6-8) with high degrees of polymerization displays an enantiotropic SX (i. e., an unidentified smectic phase) and an enantiotropic SC mesophase. These results demonstrate that the transformation of the nematic mesophase of the monomer into a smectic mesophase after polymerization, occurs at the level of monomeric structural unit.
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  • 177
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 619-628 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of epichlorohydrin (ECH) in the presence of diols, catalyzed by Lewis or protic acids, proceeds by activated monomer mechanism (AMM), i.e., by subsequent additions of protonated monomer molecules to the terminal hydroxyl groups of the growing chain. As opposed to the typical active chain end mechanism, side reactions, including cyclization, are strongly suppressed in the polymerization by AMM and well-defined linear product are obtained. It follows from kinetic considerations, that in order to achieve the high contribution of AMM, the reaction should be carried out at low instantaneous concentration of monomer, and this can be accomplished by slowly adding ECH to the reaction mixture. Using this approach, polyepichlorophydrin diols have been prepared in the M̄n ∼ 2500 products with DPn = [M]0/[I]0 can be obtained practically free of cyclic by-products with the yields approaching quantitative. Polyepichlorohydrin diols obtained by AM polymerization are strictly bifunctional, regular head-to-tail polymers containing mainly (≥ 95%) secondary hydroxyl and groups.
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  • 178
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 611-618 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polydimethylsiloxane (PDMS)-polyamide multiblock copolymers were successfully synthesized via diisocyanate route by two different procedures, i.e., the one-step and two-step methods, In the two-step method, α, ω-diisocyanate-terminated polyamide oligomers, which were prepared in situ from a mixture of isophthalic acid (IPA) and azelaic acid (AZA) with 4,4′-methylenedi (phenyl isocyanate) (MDI) in 1,3-dimethyl-2-imidazolidone (DMI) in the presence of 3-methyl-1-phenyl-2-phosopholene 1-oxide catalyst, were reacted with α, ω-bis (10-carboxydecyl) polydimethylsiloxane (PDMS-diacid) leading to the formation of multiblock copolymers. In the one-step method, the reaction components, MDI, IPA, AZA, and PDMS-diacid were reacted all together in DMI in the presence of the catalyst. These polymerizations gave multiblock copolymers having inherent viscosities in the range of 0.36-1.12 dL/g in N,N-dimethylacetamide (DMAc). These multiblock copolymers were soluble in amide-type solvents, and transparent (or translucent) and ductile films could be cast from the solutions in a mixture of DMAc and bis(2-ethoxyethyl) ether. The multiblock copolymers prepared by the two-step method had better-defined, microphase-separated morphology than those obtained by the one-step method. The mechanical properties of PDMS-polyamide multiblock copolymer films were found to be highly dependent on the PDMS content; the tensile strength and modulus of the films decreased with increasing the PDMS content.
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  • 179
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 651-655 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Elastomeric polymer consisting of poly(oxytetramethylene) segments and viologen units (PTV) was synthesized by the reaction of dicationic living poly(tetrahydrofuran) with 4,4′-bipyridine at -70°C. The chloride or bromide ion was introduced as the counter anion into the viologen groups of PTV by the treatment of the reaction mixture with aqueous sodium chloride or bromide, respectively. The solid film of PTV having chloride inon showed photochromism, i.e., color change by light irradiation, via photoreduction of the violegen groups. In contrast. PTV of bromide counter anion required a small amount of poly(N-vinyl-2-pyrrolidone) to undergo the photochromic reaction. The irradiation of light also affected the stress relaxation of the polymers, namely PTV showed photomechanical behavior. This phenomenon is considered to be induced by the decrease of total number of ionic charges of PTV by photo-reduction of the viologen groups followed by the change of a state of ionic clustering in the polymer matrix.
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  • 180
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 703-708 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A user-friendly program has been developed to estimate copolymerization reactivity ratios based on a nonlinear minimization algorithm. The use of an optimal experimental design for copolymerization when the Mayo-Lewis model applies is presented. The applicability of the program is demonstrated using actual and simulated experimental data.
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  • 181
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 709-718 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The soapless emulsion polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) containing various concentrations of sodium methacrylate (NaMA) or methacrylic acid (MMA) is studied. The hydrosoluble yields in final latexes are not larger than 1.3-5%, depending on the concentration of NaMA used. Below 25% conversion, the change of conversion with reaction time follows the square rule and the particle size is proportional to the 2/3 power of time. Above 25% conversion, serious gel effect occurs, and the conversion follows the seventh power on time and the growth of particle diameter obeys the 2.5 power on time. The multiple glass transition (Tg) occur below 20% conversion, where monomer droplets exist. NaMA added induces more Tgs. The effect of molecular weight of the copolymers obtained on Tg (even the molecular weight distributions were shown to be shouldertype bimodal) is estimated to be insignificant. Thus, the heterogeneity of copolymer compositions for multiple Tgs is ascribed to be caused from neither the molecular weight heterogeneity nor the shifts in compositions due to the difference of the monomer reactivity ratios. Referring to the results mentioned, we assume the sublayer surrounding the particle, rich with SO4- and COO- groups, and the concentration gradients of monomers in particles to illustrate particle morphology. In addition, the relatively hydrophilic sublayer is proposed to be closely relative with the occurrence of the composition heterogeneity in particles.
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  • 182
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 767-772 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new polymer-forming monomer, 3,4-bis(4-aminophenyl)-2,5-diphenylpyrrole, was synthesized in three steps starting from 4′-nitrodeoxybenzoin. Tetraphenylpyrrole-containing aromatic polyamides and copolyamides were prepared from the diamine with various aromatic diacid chlorides and from a mixture of the diamine and 4,4′-oxydianiline with terephthaloyl chloride, respectively. The resultant polymers had inherent viscosities in the 0.3-1.8 dL/g range and were generally soluble in various organic solvents including N,N-dimethylacetamide and m-cresol. They have glass transition temperatures in the range of 306-333°C and showed no weight loss below 380°C in both air and nitrogen atmospheres.
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  • 183
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 825-829 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyamides were synthesized from diacids containing a s-triazine ring and two aromatic diamines, namely 4,4′-diaminodiphenyl ether (ODA) and 4,4′-diaminodiphenylmethane (MDA), by direct polycondensation using the phosphorylation reaction. Polymers thus obtained were characterized by viscosity measurement, IR spectroscopy, thermogravimetry, X-ray diffraction, and solubility tests. These polyamides had inherent viscosities in the range of 0.51-0.77 dL/g, and were amorphous in nature. All the polymers were readily soluble in various organic solvents and did not lose weight below 270°C in air.
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  • 184
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 849-856 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photooxidation of blends of polystyrene and poly (vinyl methyl ether) was studied at 30°C. The oxygen uptake by PS was negligible but PVME oxidized readily. The induction period of oxidation of PVME was prolonged by the presence of PS. The steady state rate of oxidation of the blend was strongly influenced by the segmental mobility of the blend which also governed the kinetics and morphology of phase separation. The molecular weight of PVME decreased more slowly in the blend as PS content increased. It was believed that the reaction between PVME radicals and PS resulted in less reactive PS radicals which retarded oxidation. The PS radicals eventually underwent chain scission reactions.
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  • 185
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of p-chlorostyrene (pClSt) under carbocationic conditions has been investigated. The use of binifers 1,4-di(2-chloro-2-propyl) benzene (pDCC) and 1,3-di(2-chloro-2-propyl)-5-tert-butylbenzene (m-tBuDCC) in conjunction with BCl3 coinitiator in CH3Cl diluent at -60 and -35°C give α,ω-di-benzylic chlorine-capped polymer sCl—PpClSt—Cls. According to kinetic investigations the inifer mechanism is operative and both binifers are efficient in controlling the end structures, molecular weights, and to a certain extent molecular weight distributions (MWD). Strong circumstantial evidences have been generated to demonstrate the satisfactory synthesis of sCl—PpClSt—Cls and the absence of indanyl end-groups, i.e., structural considerations, linearity of inifer plots, quantitative Cl end-group microanalysis, FTIR spectroscopy, and blocking experiments. The latter involved the blocking of THF from the sec-benzylic chlorine end-groups by AgPF6 and thus led to the synthesis of a new triblock copolymer PTHF-b-PpClSt-b-PTHF. Interestingly, the isotactic content (mm triads and mmmm pentads) of PpClSt is significantly higher than that of polymer prepared by free-radical induced polymerization. The Tg of a PpClSt of M̄n = 5700 g/mol was 123°C.
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  • 186
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 187
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and properties of polytitanosiloxanes (PTS) as a preceramic polymer for SiO2-TiO2 fibers were investigated. The PTS was prepared by the reaction of bis(2,4-pentanedionato) titanium diisopropoxide (PTP) with silicic acid (SA), extracted with tetrahydrofuran from an aqueous solution, in methanol. They were soluble in methanol, ethanol, and THF. The molecular weight (Mn) was 1500-4200 depending on the reaction molar ratio (SA/PTP). A Concentrated methanol solution of PTS showed an appreciable stability to self-condensation and good spinnability. Dry spinning of the solution provided golden yellow precursor fibers which can be subjected to thermal-treatment to give ceramic fibers. The PTS is considered to be a copolymer formed by the condensation of oligomeric silicic acid with PTP consisting of Si—O—Ti and Si—O—Si linkages in the molecular main chain with the ligand and hydroxy groups as pendants.
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  • 188
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to clarify the general kinetic behavior of emulsion polymerization initiated by oilsoluble initiators, the emulsion polymerization of styrene initiated by 2,2′-azoisobutyronitrile was as a typical example, investigated thoroughly. The variations of the polymerization rate and the number of polymer particles produced with changes in emulsifier (sodium lauryl sulfate), initiator, and monomer concentrations initially charged and the reaction temperature were determined. It is shown from these experimental results that the kinetic behavior of this emulsion polymerization system is quite similar to that of styrene emulsion polymerization initiated by the water-soluble initiator, potassium persulfate despite the difference in the principal loci of radical production in both systems.
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  • 189
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1023-1030 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Soluble copolymers of 4-methacryloyloxy-acetanilide (M), an acrylic derivative of paracetamol, with 2-hydroxyethyl-methacrylate (H) were prepared by free radical polymerization in DMF solution at 50°C, using 2,2′-azobisisobutyronitrile (AIBN) as initiator. The reactivity ratios of both monomers were determined by the application of conventional linearization methods suggested by Fineman-Ross and Kelen-Tudos. The results obtained make clear that this system copolymerizes at random with the reactivity ratios rm = 2.15 ± 0.05 and rH = 0.90 ± 0.10. The microstructure of copolymer chains is described on the basis of the first order Markov statistics. The copolymer glass transition temperatures were determined calorimetrically and the variation of Tg with the copolymer composition is discussed according to modern methods, considering the sequence distribution of monomeric units along the copolymer chains. Also the Tg of the corresponding homopolymers were determined giving the values of Tg(M) = 471 K and Tg(H) = 358 K.
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  • 190
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1-7 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plasma-induced polystyrene radicals were first studied by electron spin resonance (ESR). The room temperature ESR spectrum was compared with those obtained by γ-irradiation, UV-irradiation, and mechanical fracture. It was found that even less than a few seconds of plasma-irradiation gave rise to a large amount of polystyrene radicals and the ESR spectrum consisted of two types of spectra, a triplet and a single broad line. The spectral feature of the triplet was nearly identical with that of γ-irradiated polystyrene. Thus, it was assigned to the structure of a cyclohexadienyl-type radical formed by a nearly random addition of a hydrogen atom to the aromatic ring. The single broad line, thought to be an outline of multicomponent spectrum, was assigned to an immobilized dangling-bond sites at the plasma-induced crosslinked portion of the polystyrene surface.
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  • 191
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 45-53 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oriented and unoriented films of noncrystalline, wholly-aromatic, rodlike polyamides, and polyesteramides were examined by infrared spectroscopy. The results indicate that orientation, accomplished by means of mechanical stretching, approaches 80% in both polymer classes. Examination of the NH and the CO stretching region revealed an increase in the population of nonhydrogen bonded species (plateauing at ∼ 85%) as orientation increases. This unusual result may be caused by interchain steric interactions which may also be responsible for both the noncrystalline morphology and the non-lyotropic behavior exhibited by these polymers.
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  • 192
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 135-137 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 193
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 317-325 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct sulfonation of tert-chloride-terminated polyisobutylene was carried out using acetyl sulfate in methylene chloride/hexanes diluent to produce low molecular weight model ionomer systems with narrow molecular weight distribution. The room temperature sulfonation of 2-chloro-2,4,4-trimethylpentane, which serves as a model for the polyisobutylene chain end obtained in the controlled cationic polymerization of isobutylene, was found to be quantitative after 3 h reaction. The two major products, isomeric β,γ-unsaturated sulfonic acids differing only in the location of the double bond, were the same products obtained from the sulfonation of 2,4,4-trimethyl-1-pentene, which serves as a model for the polyisobutylene chain end after quantitative dehydrochlorination. Near-monodisperse, tert-chloride-terminated, three-arm star polyisobutylene was synthesized under living cationic polymerization conditions using the tricumychloride/TiCl4/pyridine initiation system in hexanes/methyl chloride consolvents. Sulfonation was carried out directly upon the obtained polymer, and the sulfonated product was purified using ion-exchange chromatography. Structural elucidation was performed using NMR. Titration and molecular weight characterization revealed that sulfonation produced exactly one sulfonic acid group per polyisobutylene chain end.
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  • 194
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of cationic initiators were employed for p-isopropenylphenyl glycidyl ether (IPGE), an α-methylstyrene derivative with an epoxy pendant, and optimum initiators and reaction conditions were evaluated in terms of its selective vinyl polymerization and living polymerization. Despite the coexistence of two cationically polymerizable groups in IPGE, binary initiating systems (HI, CF3COOH, or CH3CH(OiBu)-OCOCH3, each coupled with ZnI2) and sulfonic acids (CF3SO3H and CH3SO3H) selectively polymerized the vinyl group of IPGE in CH2Cl2 at -78°C to produce soluble polymers with epoxy pendant groups in high yield. Metal halides (BF3OEt2 and AlEtCl2) polymerized both the vinyl and epoxy groups of IPGE to give crosslinked insoluble polymers. In contrast, under these conditions, the HI/ZnI2 system also led to a long-lived polymer, the molecular weight of which increased upon addition of a fresh feed of monomer to a completely polymerized reaction mixture, whereas the use of other initiators resulted in nonliving polymers. At higher temperatures (-40 and -15°C), soluble poly(IPGE) was also obtained with HI/ZnI2, but the polymer yield decreased with raising temperature, because of the occurrence of termination reaction.
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  • 195
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    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 377-391 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The esterfication of ethylene glycol (EG) with benzoic acid (BA) is an acid-catalyzed reaction which leads, as a first intermediate, to ethylene glycol monobenzoate (EGMB). This compound has an —OH group which is more active towards carboxylic groups than the first —OH group of EG. Moreover, it is a key intermediate in the formation of sideproducts containing diethylene glycol (DEG) moieties. The condensation reaction of EGMB was particularly studied in the presence of carboxylic acids or metal derivatives as catalysts. Titanium is the most active. Sb, which is widely used in the industrial synthesis of PET, needs to be present at a high level of concentration to show an activity. The presence of carboxylic groups in the reaction medium does not affect its activity, but it is necessary to remove the ethylene glycol as soon as it is formed in order to keep it active during the condensation reaction.
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  • 196
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New linear and three-arm star thermoplastic elastomers (TPEs) comprising a rubbery polysobutylene (PIB) midblock flanked by glass polystyrene (PSt) blocks have been synthesized by living carbocationic polymerization in the presence of select additives by sequential monomer addition. First, isobutylene (IB) was polymerized by bi- and trifunctional tert-ether (dicumyl- and tricumyl methoxy) initiators in conjunction with TiCl4 conintiator in CH3Cl/methylcyclohexane (MeCHx) (40/60 v/v) solvent mixtures at -80°C. After the living, narrow molecular weight, distribution PIB (M̄w/M̄n = 1.1-1.2) has reached the desired molecular weight, styrene (St) together with an electron pair donor (ED) and a proton trap (di-tert-butylpyridine, DtBP) were added to block PSt from the living chain ends. Uncontrolled initiation by protic impurities that produces PSt contamination is prevented by the use of DtBP. PSt-PIB-PSt blocks obtained in the absence of additives are contaminated by homopolymer and /or diblocks due to inefficient blocking and initiation by protic impurities, and exhibit poor physical properties. In contrast in the presence of the strong ED N,N-dimethylacetamide (DMA) and DtBP the blocking of St from living PIB chain occurs efficiently and block copolymers exhibiting good mechanical properties can be prepared. Virgin TPEs can be repeatedly compression molded without deterioration of physical properties. The products exhibit a low and a high temperature Tg characteristic of phase separated PIB and PSt domains. Transmission electron microscopy of linear triblocks containing ∼ 34 wt % PSt also indicates microphase separation and suggests PSt rods dispersed in a PIB matrix.
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  • 197
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics and sterochemical control of propylene polymerization initiated by rac-ethylene bis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride/methyl aluminoxane (1/MAO) and by rac-ethylene bis (1-indenyl) zirconium dichloride/MAO (2/MAO) were investigated. The polymerization activities increase monotonically with temperature corresponding to an overall activation energy of 10.6 kcal mol-1. This is accompanied, however, by reduction of stereochemical control as reflected in the amount of the polypropylene (PP) soluble in low boiling solvent. At a temperature of 30°C and higher, polymerization initiated by 1/MAO produced no PP insoluble in refluxing n-heptane. Tritium radiolabeling showed that at [Al]/[Zr] ≥ 3500 and 30°C, two-thirds of 1 becomes catalytically active. There are at least two kinds of active species formed in about equal amounts; one has more stereoselectivity, 10-20 times greater rate constant of propagation, and a factor of 5-15 faster chain transfer to MAO than the second kind of Active species. This is also true at low [Al]/[Zr] of 350, except that the total amount of the two active species corresponds to only 13% of the [1]. Replacement of MAO with trimethyl aluminum resulted in the decrease of stereoselectivity and loss of catalytic activity proportional to the amount of replacement. A comparison was made with the polymers obtained with 2/MAO.
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  • 198
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 525-534 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-NMR spectroscopy was used to characterize the chemical structure of sulfonated urea-melamine-formaldehyde resins, prepared by a three-step procedure (addition, sulfonation, condensation). Each of the three reaction steps was investigated separately and the average number of functional groups, obtained after each step, was determined quantitatively. The effect of the reactant ratios on the chemical structure was studied.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 199
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 697-702 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The surface grafting onto inorganic ultrafine particles, such as silica, titanium oxide, and ferrite, by the reaction of acid anhydride groups on the surfaces with functional polymers having hydroxyl and amino groups was examined. The introduction of acid anhydride groups onto inorganic ultrafine particle was achieved by the reaction of hydroxyl groups on these surfaces with 4-trimethoxysilyltetrahydrophthalic anhydride in toluene. The amount of acid anhydride groups introduced onto the surface of ultrafine silica, titanium oxide, and ferrite was determined to be 0.96, 0.47, and 0.31 mmol/g, respectively, by elemental analysis. Functional polymers having terminal hydroxyl or amino groups, such as diol-type poly(propylene glycol) (PPG), and diamine-type polydimethylsiloxane (SDA), reacted with acid anhydride groups on these ultrafine particles to give polymer-grafted ultrafine particles: PPG and SDA were considered to be grafted onto these surfaces with ester and amide bond, respectively. The percentage of grafting increased with increasing acid anhydride group content of the surface: the percentage of grafting of SDA (Mn = 3.9 × 103) onto silica, titanium oxide, and ferrite reaching 64.7, 33.7, and 24.1%, respectively. These polymer-grafted ultrafine particles gave a stable colloidal dispersion in organic solvents.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 200
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 739-747 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly crosslinked aliphatic and aromatic polyurethane-acrylate (PUA) coatings have been obtained by photopolymerization of multifunctional monomers. The discoloration and chemical modifications occurring upon accelerated QUV aging were monitored by UV and IR spectroscopy. The polymers were found to undergo photooxidation and loss of carbamate and phenyl groups, with lower quantum yields (10-3 mol photon-1) than in related linear polymers. Hydroxy-phenyl benzotriazole UV-absorbers have a limited effect on the degradation rate, at the concentration used (0.5%). Hindered amines (HALS) are substantially more effective, especially in aliphatic PUA. A 20-fold increase in the stabilization efficiency was found with the UVA + HALS combination. Aromatic PUA are more difficult to stabilize, because of the strong absorption and photolysis of the phenyl group which yields colored products. Radical-induced oxidation is predominant in aliphatic PUA and develops with long kinetic chains, while in aromatic PUA it competes with direct photolysis.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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