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
Notes:
The thermal Stability of radiation-grafted poly(vinyl chloride) (PVC) has been investigated by thermogravimetric analysis and compared with the thermal stability of the corresponding PVC polymer blends. Although both the grafting of methyl methacrylate and styrene and the blending of the corresponding homopolymers yield products of improved thermal stability as compared with unmodified PVC, the radiation grafting is somewhat more efficient for the stabilization of PVC than blending. Further, the rate of dehydrochlorination of PVC-g-styrene at relatively high temperatures exhibits a retardation, whereas that of unirradiated PVC show significant acceleration. A detailed study about a series of PVC-g-styrenes polymerized under various conditions shows that the retardation effect is more noticeable in the samples irradiated to 2.0-3.0 Mrad than in those irradiated to less than 1.0 Mrad. From the dose dependency, it has been suggested that the retardation effect is due to the interruption of the propagation of dehydrochlorination by branch sites produced by the radiation process. On the other hand, the graft copolymers of vinyl pyridines, PVC-poly(vinyl pyridine), and PVC irradiated in the presence of pyridine are much less stable than unmodified PVC. The instability is explained in terms of the substitution reaction with the bases and the base-catalyzed dehydrochlorination of PVC.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1974.070180723
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