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 sensitivity to radiation of mixtures of poly(methyl methacrylate) (PMMA) and polystyrene-co-acrylonitile) (SAN) was studied over the entire range of composition. Polystyrene-co-acrylonitrile, like polystyrene, is highly resistant to ionizing radiation, having a small Gx value for crosslinking (0.077) and an even smaller Gs value for main chain scission (0.055). In contrast, PMMA degrades readily under irradiation (with Gs = 1.2). In γ-irradiated blends, the behavior of each polymer is largely influenced by the presence of the other component. Gel formation in SAN is impeded by PMMA, as a result of a decrease in Gx, and a concomitant increase in the ratio Gs/Gx. Flexural strength measurements, along with molecular weight determinations by gel permeation chromatography, demonstrated that SAN had a marked protective effect on PMMA by decreasing Gs (chain scission). This protective effect was not observed in earlier experiments with PMMA-PS blends, in spite of its chemical similarity to the system PMMA-SAN. The difference in behavior between PMMA-PS and PMMA-SAN may be explained on the basis of polymer compatibility. PMMA and SAN form a compatible pair, whereas PMMA and PS are incompatible; thus the short range protective effect of the phenyl groups in PS is inhibited.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1984.070290202
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