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  • 1
    Digitale Medien
    Digitale Medien
    Anomalous copolymerization behavior of styrene and ethyl methacrylate at high conversion (1984)
    Springer
    Polymer bulletin 12 (1984), S. 343-348 
    Details
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Styrene and ethylmethacrylate were copolymerized in bulk at 62°C and several monomer feed ratios. At moderately high conversion, anomalous copolymerization behaviour occurred. Although the onset of the departures from expected copolymerization behaviour seems to be related to the onset of the gel-effect, this relation did not hold when mimicking higher conversion by adding an amount of homopolymer. Obviously the propagation reactions are not only affected by changes in diffusion characteristics but also by changes in other medium characteristics e.g. interactions between monomeric and copolymeric species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00263150
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  • 2
    Digitale Medien
    Digitale Medien
    Investigation of the intramolecular structure of styrene-ethylmethacrylate copolymers by 1H- and 13C-NMR: Reassignment of 1H-NMR spectra (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 1439-1456 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The compositions and sequence distributions of homogeneous styrene (S)-ethyl methacrylate (E) copolymers, obtained by low conversion solution polymerization have been studied by 1H- and 13C-NMR. A new set of peak triad assignments was proposed for the δ 2.1-4.2 ppm region in the 1H-NMR spectrum, whereby the reactivity ratios of rS = 0.59 and rE = 0.50 were used to establish this new assignment. The EEE and SSS blocks, present in these copolymers, have a high degree of syndiotacticity (σEE = 0.23, σSS = 0.39), whereas the ESE units are exhibiting a slight tendency toward isotacticity (σES = 0.66).
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1988.080260516
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  • 3
    Digitale Medien
    Digitale Medien
    Effect of molar mass ratio of monomers on the mass distribution of chain lengths and compositions in copolymers: Extension of the stockmayer theory (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 61-69 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In statistical copolymers, there exists a distribution according to molar mass as well as according to chemical composition. Stockmayer derived distribution functions, describing the relative weight of a particular molar mass and composition interval, assuming equal molar masses of the monomer units. In this article we present an extension of the distribution functions, suited for those cases where the aforementioned assumption is not valid. The final mathematical results is a product of the original Stockmayer distribution function and a correction function, due to the unequality of molar masses. It appears the correction function is dependent on the average composition, the composition deviation, and the ratio of molar masses of the monomers. Furthermore, a three-dimensional representation of distributions has been developed to get insight in the shape of the distributions.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1988.080260106
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  • 4
    Digitale Medien
    Digitale Medien
    Study on the feasibility of TLC/FID to reveal chemical composition distributions of copolymers obtained by emulsion processes (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 817-827 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The CCD (chemical composition distribution) of poly(styrene-co-ethyl methacrylate) has been determined by thin layer chromatography/flame ionization detection (TLC/FID). It appeared that a mixture of five reference copolymers obtained by solution polymerization each having a narrow CCD, could be separated in five distinct peaks, provided a modified spotting procedure and a concentration gradient elution technique were applied. All copolymers prepared by solution polymerization could be successfully characterized. Copolymers obtained by emulsion techniques using nonionic or anionic surfactants containing oxyethylene groups, or in the absence of chain length modifier behaved anomalously and appeared to have spurious CCD's. Also the average composition calculated from these CCD's did not agree with the average composition determined by 1H-NMR. This anomalous behaviour disappeared when using sodium lauryl sulfate as surfactant or when applying a chain length modifier (n-dodecyl mercaptan) during the preparation of the polymer. Several possibilities have been proposed in order to explain these phenomena. The most probable explanation seems to be reaction of a growing polymer chain with surfactant molecules resulting in a quasi-terpolymer. This polymer containing highly polar oxyethylene groups, remains strongly adsorbed on the silica surface during elution, thus disturbing the separation process.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1989.080270307
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