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  • Physics  (15)
  • Wiley-Blackwell  (15)
  • American Geophysical Union (AGU)
  • Nature Publishing Group (NPG)
  • Springer
  • Wiley
  • 2000-2004
  • 1980-1984  (10)
  • 1965-1969  (5)
  • 1945-1949
Collection
Keywords
Publisher
  • Wiley-Blackwell  (15)
  • American Geophysical Union (AGU)
  • Nature Publishing Group (NPG)
  • Springer
  • Wiley
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    A chemical study of thermally activated chromic titanate on silica ethylene polymerization catalysts (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 2857-2866 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermally activated ethylene polymerization catalysts which contain chromium and titanium on silica differ from those catalysts which contain only chromium on silica. The characteristics of chromium-titanium catalysts vary with the method of incorporating the titanium and the thermal activation procedure. Titanated catalysts of the kind examined in this article have faster initiation and a higher polymerization rate per unit catalyst weight than corresponding catalysts without titanium. High-density polyethylene produced by this type of titanium-chromium catalyst tends to have a higher melt index and a broader molecular weight distribution than polyethylene made with chromium on silica catalysts. Iodometric titration showed that reduction from the initial hexavalent chromium to trivalent occurs when the dry, catalyst starting material is treated with titanium tetraisopropoxide. A study of the reaction between chromium trioxide and titanium tetraisopropoxide in carbon tetrachloride revealed that (1) it is not necessary to have a reaction between surface silanols and titanium tetraisopropoxide for the reduction to occur, and (2) the reaction product has an absorption near 660 nm in the visible range. Comparison of spectra showed that chromium trioxide on silica reduced by isopropyl alcohol has a shifted absorption, i.e., 600 nm. These findings are interpreted to mean that titanium atoms come sufficiently close to chromium atoms to change their electron density in the starting material and remain close neighbors in the activated catalysts. The interpretation is further supported by ESCA data and leads to the proposal that in this case the activated catalysts contain titanium chromate structures.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170180908
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and thermomechanical properties of alternating copolymers containing bisphenol-A (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 3119-3127 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alternating copolymers containing 4,4-isopropylidene-bisphenol (BPA) and comonomers with various degrees of polarity have been evaluated to find comonomer structures which provide low melt viscosity and good thermal stability. The materials were prepared by pyridine-catalyzed nucleophilic displacement reactions similar to that for the preparation of BPA polycarbonate. The molecular weights of the polycarbonates depend on the concentration and nucleophilicity of the attacking diol and the concentration and stability of a colored pyridine-chloroformate adduct formed during polymerization. The greatest thermal stability occurs for BPA-DMS and BPA-DEG. Thermomechanical flow measurements and Tg measurements were used to evaluate melt viscosity. The shapes and magnitudes of the Tg vs. Tf curves are sensitive to the copolymer chemical structure.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170181021
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  • 3
    Electronic Resource
    Electronic Resource
    NMR relaxation study of crosslinked cis-1,4-polybutadiene (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 1061-1070 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton relaxation measurements have been used to investigate the effects of crosslinking on the segmental motion in cis-1,4-polybutadiene samples. The temperature dependence of proton spin-lattice relaxation time T1 and spin-spin relaxation time T2 at 60 and 24.3 MHz are reported in cis-1,4-polybutadiene (PB) samples with different crosslink density including uncrosslinked PB and samples with 140, 40, and 14 repeat units between crosslinks. In addition, spin-lattice relaxation times in rotating coordinate frame, T1p, have also been determined. The relaxation data are interpreted in terms of the effects of crosslinks on segmental chain motions. Because of their sensitivity to low-frequency motion, T2 data are of major interest. At temperatures well above the T1 minimum the small T2 temperature dependence resembles solidlike behavior reflecting the nonzero averaging of dipolar interactions due to anisotropic motion of the chain segments between crosslinks. The magnitude of T2 at 60°C is found to be proportional to the average mass between crosslinks.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170180324
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  • 4
    Electronic Resource
    Electronic Resource
    High-resolution NMR spectra and phase equilibria in poly(phenylacetylene)-diluent mixtures (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 2277-2286 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The C-13 NMR spectra of partly crystalline poly(phenylacetylene) (PPA) in CDCl3 CCl4 are rather well resolved and the peaks can be matched with those of 1, 3,5-triphenylbenzene. A different, less-well-resolved C-13 spectrum is characteristic of a disordered PPA obtained by heating. We conclude that crystalline PPA has the chain conformation of a cis-cis-oid helix. This interpretation is consistent with the proton NMR spectra and is supported by the fluorescence spectra, which can display two bands, one concluded to be characteristic of the cis-cis-oid conformation, the other of chain conjugation in the disordered polymer. Phase equilibria of PPA in the presence of chloroform were determined and are represented as those of the quasiternary mixture cis-cis-oid helix, disordered polymer, and chloroform.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.180181112
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  • 5
    Electronic Resource
    Electronic Resource
    Magic-angle 13C NMR of solid polyphenylacetylenes (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1151-1152 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.180190711
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  • 6
    Electronic Resource
    Electronic Resource
    Decay of the ESR signal in ultraviolet-irradiated poly(methyl methacrylate) (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 677-680 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050325
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  • 7
    Electronic Resource
    Electronic Resource
    Photopolymerization initiated by triphenylphosphinePresented at the 149th Meeting of the American Chemical Society Division of Polymer Chemistry, Detroit, Michigan, April 4-9, 1965. (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 1741-1751 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The triphenylphosphine-initiated photopolymerization of acrylic monomers was studied. Only those monomers containing an α,β-unsaturated carbonyl group could be photoinitiated by triphenylphosphine, styrene being unaffected at the level of initiator employed. Kinetic studies with methyl methacrylate showed that the propagation was free radical in nature. Analysis of the resulting polymer indicated that it contained one phosphorus atom per chain. Ultraviolet spectral data suggested the formation of complexes between the triphenylphosphine and each monomer for which it is initiator. A relationship between the complex and the polymerization was shown to exist. A mechanism is proposed, involving a light-activated dipole interaction between the carbonyl oxygen and the phosphorus atom with the ultimate formation of a methacrylate type of free radical.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050722
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  • 8
    Electronic Resource
    Electronic Resource
    Anionic graft polymerization of lithiated poly(2,6-dimethyl-1,4-phenylene ether) (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 2537-2545 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithiated poly(2,6-dimethyl-1,4-phenylene ether) has been used as an initiator for the graft polymerization of isoprene, methyl methacrylate, hexamethylcyclotrisiloxane, and phenyl isocyanate with the use of toluene and tetrahydrofuran as solvents. The products were examined by gel-permeation chromatography for evidence of homopolymerization and graft polymerization. The composition of the graft copolymers was determined by NMR, and for isoprene and hexamethylcyclotrisiloxane, termination by trialkylchlorosilanes enabled chain lengths to be determined by NMR. The use of toluene gave rise to some homopolymerization, but with tetrahydrofuran, only hexamethylcyclotrisiloxane gave homopolymer. In all cases, graft copolymers were formed. With isoprene and methyl methacrylate, soluble graft copolymers were formed in good yield. In the former case approximately 60% 3,4 and 40% 1,4 addition was found. In the latter case 1,1-diphenylethylene was used to reduce crosslinking, in its absence, methyl methacrylate gave only crosslinked gels in tetrahydrofuran. Hexamethylcyclotrisiloxane added only one molecule per lithium on the polymer, the remainder giving homopolymer. Phenyl isocyanate gave some soluble graft copolymer in toluene, but only crosslinked products were obtained when tetrahydrofuran was used as reaction solvent.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.150070907
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  • 9
    Electronic Resource
    Electronic Resource
    Graft polymerization of styrene on lithiated poly(2,6-dimethyl-1,4-phenylene ether) (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 1359-1369 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Styrene has been grafted onto poly(2,6-dimethyl-1,4-phenylene ether) (I) with the use of lithiated I as an initiator. In benzene solution, solvent metalation resulted in some polystyrene homopolymer. In tetrahydrofuran, however, only graft copolymer was formed. By forming a derivative with trimethylchlorosilane and examining by NMR, it was possible to establish the proportion of lithium scavenged by impurities, the amount of polymeric lithium which reacted with styrene, and the amount which did not. The chain length of the grafted polystyrene was also calculated. No crosslinking was found, except where a high ratio of lithium to styrene resulted in some unreacted ring-metalated polymer. In this case only, reaction with trimethylchlorosilane causes some crosslinking.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.150070518
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  • 10
    Electronic Resource
    Electronic Resource
    Stress relaxation of natural rubber during irradiation (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 7 (1969), S. 725-733 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The site of chain scission and crosslinking in vulcanized natural rubber irradiated with 4 MeV electrons has been determined by analysis of stress relaxation data. Sulfur and peroxide vulcanizates of different crosslink densities were prepared and the crosslink densities determined from stress-strain measurements. Stress relaxation was measured during irradiation using modified commercial relaxometers. The specimens were maintained in an atmosphere of nitrogen to minimize oxidative side effects. Scission is deduced to take place in the vicinity of crosslinks, since the rate of continuous stress relaxation is independent of crosslink density. Scission may be associated both with crosslinks initially present and with those subsequently introduced by irradiation. Crosslinking by radiation is largely a random process. However, there is a crosslinking reaction dependent to a slight extent on crosslink density as well as a small contribution from random scission reactions. G values for the random reactions are given.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.160070410
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