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  • Physics  (8)
  • Wiley-Blackwell  (8)
  • Cambridge University Press
  • 2015-2019
  • 1985-1989
  • 1970-1974  (8)
  • 1945-1949
  • 1
    Electronic Resource
    Electronic Resource
    Poly α-ester degradation studies. IV. Rheological studies of polymer degradation (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 2031-2043 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Farol-Weissenberg rheogoniometer has been used to follow molecular weight changes during the degradation of certain poly-α-esters in the melt state. By observing the change in melt viscosity at low shear rates it had been shown that the decomposition of the poly(isopropylidene carboxylate) is substantially first-order with respect to the molecular weight of the residual polymer. The derived kinetic parameters are in good agreement with those previously obtained by other techniques. This provides a substantial piece of supporting evidence for the view that degradation takes place predominantly by intramolecular ester interchange involving the formation of 1,1,4,4,-tetramethylglycollide. The introduction of β-chlorine atoms into the polymer structure leads to a more complex degradation pattern. Thus the presence of a single β chlorine atom per repeat unit, as in poly(3-chloro-2-methyl-2-hydroxypropionic acid) leads to a substantially similar dependence on molecular weight with the added complication of progressive crosslinking which becomes more apparent in later stages of the reaction. This crosslinking reaction plays an increasingly important part as the extent of chlorination of the polymer is increased. In addition, the presence of chlorine leads to an increased sensitivity of the degradation reaction to the presence of oxygen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110822
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  • 2
    Electronic Resource
    Electronic Resource
    Cationic copolymerization of tetrahydrofuran with epoxides. II. Characterization and gel-permeation chromatography of by-products formed during polymerization (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 281-294 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyclic oligomers formed as by-products in the polymerization of propylene oxide. 1,2-butylene oxide, and n-propyl glycidyl ether, and in the copolymerization of these monomers with tetrahydrofuran have been studied by gel-permeation chromatography and otherwise and their structures have been determined. Some of the physical properties of the cyclic oligomers are described.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090203
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  • 3
    Electronic Resource
    Electronic Resource
    Cationic copolymerization of tetrahydrofuran with epoxides. I. Polymerization mechanism in the presence of a glycol (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 265-279 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of several epoxides and their copolymerization with tetrahydrofuran have been studied. The polymerizations were carried out by use of BF3·O(C2H5)2 as catalyst in the presence of 1,4-butanediol. Variations of catalyst and 1,4-butanediol ratio and concentration affect polymerization rate, molecular weight, and the formation of cyclic oligomers. The latter is also influenced by monomer fed ratio in the case of the copolymerizations. These effects are discussed, and some observations are made concerning the mechanism, particularly with respect to the role of the 1,4-butanediol. Mayo-Lewis monomer reactivity ratios were determined. The ratios found differed from previously published figures.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090202
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  • 4
    Electronic Resource
    Electronic Resource
    Cationic copolymerization of tetrahydrofuran with epoxides. III. Synthesis of block copolymers (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 295-298 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of various cyclic ethers by BF3·O(C2H5)2 in the presence of polymeric glycol leads to the formation of hydroxyl terminated block copolymers. Where poly(oxyethylene glycol) is used as the polymeric glycol, fission of the poly(oxyethylene glycol) chain occurs, and block copolymers, containing shorter ethylene oxide unit sequences are obtained. With poly(oxypropylene glycol), on the other hand, the polymer chain remains intact. This may be due to the steric influence of the pendant methyl groups. The cyclic oligomers formed as by-products in the polymerizations are easily removed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090204
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  • 5
    Electronic Resource
    Electronic Resource
    Permeation of dimethyl sulfoxide through polyethylene membraness (1972)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 10 (1972), S. 295-305 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Permeability and diffusion coefficients for dimethyl sulfoxide (DMSO) in polyethylene have been measured by the “time-lag” technique and found to be affected by the adsorption of DMSO vapor in the low-pressure side of the apparatus. An analytical method is described for correcting the apparent permeability coefficients for such adsorption effects. “True” permeability coefficients for DMSO in polyethylene, expressed in units of cm3(STP) - cm/(sec-cm2-cmHg), vary from 0.92 X 10-7 at 30°C to 1.7 X 10-7 at 45°C, and their dependence on relative DMSO pressure appears to be small. The energy of activation for the permeation process is 7.1 kcal/mole. The described correction method is also applicable to the permeation of water vapor through polyethylene and poly-(phenylene oxide). The apparent diffusion coefficients could not be corrected by this method. The solubility of DMSO in polyethylene was measured with a Bakr-McBain balance and found to be very small; solubility coefficients are less than 0.8 cm3(STP) DMSO/(cm3 polymer-cmHg). It is concluded that the transport and solution behavior of DMSO in polyethylene is more similar to that of water vapor than to the corresponding behavior of organic vapors.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1972.160100209
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  • 6
    Electronic Resource
    Electronic Resource
    Phenolic resins for solid-phase peptide synthesis: Copolymerization of styrene and p-acetoxystyrene (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 2017-2025 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Details are given of the synthesis and purification of p-acetoxystyrene and its solution and suspension copolymerization with styrene. Reactivity ratios, evaluated by the Tidwell-Mortimer method, were r1 (p-acetoxystyrene) = 1.18, and r2 (styrene) = 0.88 for (bulk) solution copolymerization. Corresponding values of the reactivity ratios for suspension copolymerization were, within experimental error, indistinguishable from unity. Thus the copolymer composition is governed simply by the monomer feed composition. Use of a specially designed reactor vessel permits convenient suspension copolymerization of styrene, p-acetoxystyrene, and divinylbenzene to give crosslinked resins having comparatively narrow particle size distributions. Acetoxy groups in the crosslinked resin are cleaved by hydrazine hydrate under very mild conditions to give crosslinked polystyrenes having phenolic groups which, in turn, provide a useful alternative to the more usual chloromethylated polystyrene resins for solid-phase peptide synthesis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120915
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and reactions of polyvinylcyclopropane (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 8 (1970), S. 359-376 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinylcyclopropane was polymerized with a catalyst of diethylaluminum chloride and titanium trichloride and fractionated to yield isotactic, atactic, and stereoblock fractions, as shown by a combination of physical and chemical evidence. The atactic fraction contained a significant portion of product from 1,5-polymerization as well as the usual 1,2-polymerization, and this occurrence is explained by modifications in a mechanism for normal 1,2-coordination polymerization such that abnormal alkylations occur during the propagation step in the coordination sphere of the catalyst surface. Addition of hydrogen bromide to the isotactic fraction yielded predominantly poly-3-bromo penten-1 and in-chain cyclohexane and vinylidene structures. A mechanism is proposed for these occurrences involving a hydride shift and various reactions of the initially generated carbonium ion with neighboring cyclopropyl rings. Addition of acetic acid yielded 25% addition and 25% cyclization and crosslinking. Hydrogen sulfide did not add to the cyclopropyl ring. Hydrogenation of the atactic fraction yielded poly-3-methylbutene-1 quantitatively, demonstrating that the polymeric environment did not affect the direction of ring opening but that the state of crystallinity as compared to the isotactic polymer did affect the extent of reaction. In general, the cyclopropyl ring in a polymeric environment underwent its usual reactions but was subject to reactions with neighboring groups resulting from its fixation in a polymer chain.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.150080208
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal analyses of polymers. III. Influence of isocyanate structure on the molecular interactions in segmented polyurethanesIn honor of C. S. Marvel on the occasion of his 75th brithday.,Presented at the Polymer Division Symposium on Polyurethanes, American Chemical Society, Atlantic City, September 1968. (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 8 (1970), S. 1923-1937 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal responses of various polyurethane elastomers in the form of changes in heat capacity, linear expansion, and tensile strain have been examined. Most of the change which can be attributed to the backbone of polyethylene adipate, found in several modes of thermal analysis, are still apparent, though shifted somewhat, among most of the diisocyanate extended elastomers used in this study. Tolylene diisocyanate extension changes the modulus properties markedly, low modulus properties being observed at ambient temperatures. Both hydrogenated MDI and MDI elastomers show comparable expansion and modulus response, whereas the hydrogenated TDI elastomer does not have the same characteristics as TDI-based elastomers. The thermal properties of the hydrogenated TDI elastomer resemble more those exhibited by the polyol mixture extended with hexamethylene diisocyanate, and in addition this latter elastomer exhibits more crystallinity, as shown by the large endotherm in the specific heat measurement. The structure of the diisocyanate naturally changes the behavior of the hard segment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.150080802
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