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  • Polymer and Materials Science  (13)
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  • 1
    Electronic Resource
    Electronic Resource
    Mastication. Part III. Chemical verification of the mechanical degradation mechanism of cold mastication (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 19 (1956), S. 1-15 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism of cold mastication of natural and synthetic rubbers, as proposed by Kauzmann and Eyring, and by Pike and Watson, in volves the mechanical rupture of the polymer chain yielding polymer radicals which are stabilized by interaction with radical-acceptor molecules to give the degraded polymer. This mechanism has been verified by a spectroscopic study of the cold mastication of natural rubber with 1,1-diphenyl1-2-picryl hydrazyl and a radioisotopic tracer study of the cold mastication of GR-S using [S35]-labeled 1,1′-dinaphthyl disulfide as the radical-acceptor molecule. Correlation of the decrease in molecular weight of the polymer and the amount of radical acceptor in corporated during the cold mastication process agrees with prediction according to the mechanical degradation mechanism.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.120199101
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  • 2
    Electronic Resource
    Electronic Resource
    The use of [C14]-labeled initiators in determining the termination reaction in methyl methacrylate free-radical polymerization: The importance of molecular weight measurements (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 22 (1956), S. 549-551 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.1202210222
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  • 3
    Electronic Resource
    Electronic Resource
    Radiochemical studies of free-radical vinyl polymerizations. Part I. The nature of the initiation and termination processes in methyl methacrylate and styrene polymerizations using C14-labeled initiatorsThe work described in this paper and Part II was submitted by G. Ayrey in a Thesis for the Ph.D. degree to the University of London, February, 1957. (1959)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 36 (1959), S. 41-53 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: C14-Labeled initiators, viz., di-(ar-C14)-benzoyl peroxide, di-(carboxyl-C14)-benzoyl peroxide, and C14-azobisisobutyronitrile (AZBN), have been used to initiate the polymerization of methyl methaerylate at 60°C. in benzene. Determination of the rates of polymerization, and the molecular weights (M̄n) and C14-contents of the resultant polymers permits the following conclusions to be made. (1) Rates of initiation by benzoyl peroxide and AZBN are given by the equations, Ri = 5.15 × 10-6 [Bz2O2] mole l.-1 sec.-1 and Ri = 1.17 × 10-5[AZBN] mole l.-1 sec.-1, respectively. (2) The initiator efficiency, f, for AZBN is 0.50; f for benzoyl peroxide cannot be evaluated in the absence of a reliable kd value for this compound in the present system. (3) Initiation is solely by addition of initiator radicals, R·, to the monomer; in the case of benzoyl peroxide, 43% of the radicals R· are phenyl and 57% are benzoyloxy under the reaction conditions used. (4) The average number of C14-initiator fragments per polymer molecule, n, is 1.27, indicating that bimolecular termination of polymethyl methacrylate radicals is 57.5% by disproportionation and 42.5% by combination.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1959.1203613005
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  • 4
    Electronic Resource
    Electronic Resource
    Radiochemical studies of free-radical vinyl polymerizations. Part II. The polymerization of vinyl monomers in the presence of polyisoprenes: Use of C14-labeled initiators to determine the mechanism of graft-interpolymer formationPart I, G. Ayrey and C. G. Moore, preceding paper. (1959)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 36 (1959), S. 55-76 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of methyl methacrylate at 60°C. by benzoyl peroxide in benzene solutions of polyisoprenes (e.g., natural rubber and gutta-percha) yields polymethyl methacrylate and a graft interpolymer having polymethyl methacrylate side chains attached to the polyisoprene backbone. Use of azobisisobutyronitrile (AZBN) as initiator in comparable systems gives free polymethyl methacrylate, but no graft interpolymer. The cause of this specific initiator effect, and the mechanism of graft polymerization have been determined by using C14-labeled initiators. Benzoyl peroxide initiates graft polymerization by prior reaction of the derived phenyl and benzoyloxy radicals with the polyisoprene by addition to the double bond, and by abstracting α-methylenic hydrogen atoms to give polyisoprenic alkyl and alkenyl radicals, respectively, which act as loci for methyl methacrylate polymerization. In the system gutta-percha-methyl methacrylate, at 60°C., 35-45% of the grafted vinyl polymer side chains are initiated by hydrogen abstraction, and about 90% of the initiator radicals undergoing addition to the double bond are benzoyloxy. The modes of termination of the grafted and free polymethyl methacrylate radicals have been evaluated semiquantitatively, and it is found that, in the graft interpolymer, 13-27% of the polymethyl methacrylate chains have both ends attached to gutta-percha chains (i.e., have an “I” structure), while 73-87% are attached at one end only to gutta-percha chains (i.e., are “T” structures). The reliability of the separatory procedure previously devised8 to resolve the bulk polymer obtained in the graft-polymerization system has now been verified by use of the isotopedilution technique. The inability of AZBN to initiate graft polymerization is attributed to the markedly inferior capacity of the resonance-stabilized Me2Ċ(CN) radicals, relative to C6H5· and C6H5COO·, to engage in double bond addition and hydrogen abstraction reactions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1959.1203613006
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  • 5
    Electronic Resource
    Electronic Resource
    The degradation and stabilization of polyacrylonitrile. I. Evidence for β-ketonitrile defect structures as initiators of degradation (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 2249-2258 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory that β-ketonitrile structures initiate discoloration reactions in polyacrylonitrile has been tested by a number of methods. Using radiochemical techniques the numbers of carbonyl groups in various polymers have been measured as have the amounts of combined water. A model β-keto compound, 1,3,7,-tricyanoheptan-4-one was synthesized and its reactions studied. None of these experiments supported the idea that β-ketonitrile structures are of primary importance in initiating the degradation of polyacrylonitrile.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200827
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  • 6
    Electronic Resource
    Electronic Resource
    The use of organotin compounds in the thermal stabilization of poly(vinyl chloride). VI. An assessment of the relative importance of HCl-scavenging, exchange, and addition reactions (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2871-2886 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of PVC with three representative stabilizers Bu2SnY2 (Y = OCOC11H23, SCH2COOCH2CH(Et)CH2CH2CH2CH3, OCOCH=CHCOOMe) in solution and under nitrogen were studied by two principal methods. First, using stabilizers with radioactive labels in the Y groups, the uptake of these groups by virgin and degraded polymer was measured. The UV-visible absorption spectra of the stabilized polymers are discussed. Second, the effect of these three stabilizers on the rate of elimination of hydrogen chloride from heated PVC was studied. It is shown that the effects of HCI-scavenging and of exchange reactions in suppressing the evolution of HCI can be separately evaluated. The thermal decomposition of dibutyltin bis(methyl maleate) to give maleic anhydride is reported. Interpretation of the observations is made in terms of assessing the relative importance of the various polymer-stabilizer reactions in promoting stabilization.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.170221112
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  • 7
    Electronic Resource
    Electronic Resource
    Radiochemical studies of free-radical vinyl polymerizations. VI. Polymerization of methyl methacrylate in the presence of organotin PVC stabilizers (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 13 (1975), S. 69-75 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 14C-Azoisobutyronitrile was used to initiate polymerizations of methyl methacrylate in the presence of the organotin compounds: tetrabutyltin, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin di(ethyl mercaptide), dibutyltin di(dodecyl mercaptide), and dibutyltin dichloride. Only dibutyltin dichloride affected rates of polymerization significantly, and this was ascribed to an increase in the velocity constant kp for the propogation reaction. No evidence was obtained for radical displacement reactions of the polymer radicals with bonds between tin and carbon, oxygen, sulfur, or chlorine. Transfer activity exhibited by the mercaptides was ascribed to traces of thiol impurity, possibly formed during storage. The relevance of these results to the mechanism of stabilization of poly(vinyl chloride) is briefly discussed.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.170130107
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  • 8
    Electronic Resource
    Electronic Resource
    Osmotic and viscometric characterization of poly(p-chlorostyrene) and poly(p-methoxystyrene) (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 2621-2623 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070190923
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  • 9
    Electronic Resource
    Electronic Resource
    A radiochemical study of the Ziegler-Natta catalysed polymerization of styreneSubmitted by R. J. M. as part of a Ph. D. Thesis, University of London, 1968. (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 3353-3370 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Styrol in Benzollösung wurde bei 60°C und mit einem Katalysator aus α-Titantrichlorid und [14C]-Triäthylaluminium untersucht. Die dabei erhaltenen Ergebnisse zeigten, daß es unzulässig ist, die Anzahl der aktiven Zentren an den Katalysatoten auf diese Weise zu bestimmen, da hierbei die Anzahl mannigfach überschätzt werden kann. Versuche mit Isotopenverdünnungen zeigten, daß die radioaktive Verunreinigung auf die Gegenwart von freiem und gebundenem [14C]-Polyäthylen zurückzuführen war. Die Anzahl der aktiven Zentren kann besser bestimmt werden, wenn die Polymerisation mit tritiiertem Methanol abgebrochen wird. Die dadurch erreichten Werte sind viel realistischer. Es wurde auch bewiesen, daß die entscheidende Reaktion die das Molekulargewicht des Polymers bestimmt, eine Übertragungsreaktion mit Aluminiumalkyl ist.
    Notes: The polymerization of styrene in benzene solution was studied at 60°C using a catalyst composed of α-titanium trichloride and [14C]triethylaluminium. The results obtained showed that the use of this system to measure the number of active sites on the catalyst is an unreliable method likely to over-estimate the number manifold. Isotope dilution experiments indicated that the contamination was due to the formation of both free and bound [14C]polyethylene. Use of tritiated methanol as a quenching agent to measure active centres indicated that this method yielded results much nearer to the true values. Evidence was also obtained to show that the main reaction governing polymer molecular weight was chain transfer with aluminium alkyl.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021761118
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  • 10
    Electronic Resource
    Electronic Resource
    The thermal dehydrochlorination and stabilization of poly(vinyl chloride) (1974)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science: Macromolecular Reviews 8 (1974), S. 1-49 
    Details
    ISSN: 0076-2083
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.230080101
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