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Effect of initial crystallinity on the response of high‐density polyethylene to high‐energy radiation
Author(s) -
Failla M. D.,
Vallés E. M.,
Lyons B. J.
Publication year - 1999
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19990228)71:9<1375::aid-app3>3.0.co;2-j
Subject(s) - crystallinity , materials science , brittleness , irradiation , ultimate tensile strength , composite material , polyethylene , polymer , modulus , elongation , physics , nuclear physics
Samples of each of two high‐density polyethylenes with various initial degrees of crystallinity, but otherwise identical, were exposed under a vacuum to moderate doses of gamma irradiation. The results indicate that, for otherwise initially identical polymer samples, the dose required to reach the gel point increases with increase of the initial degree of crystallinity. Above the critical dose for gelation, the gel content decreases with higher degrees of crystallinity at equal radiation doses. The mechanical behavior of the polymers changed progressively from ductile to brittle as the crystallinity was increased. The extensibility of originally ductile samples decreases with increasing radiation dose. The irradiation of samples having intermediate behavior produces a change to ductile behavior. Mechanical behavior is not modified substantially when brittle samples are irradiated. The initial modulus is little altered by irradiation, while the yield stress shows a slight increase with irradiation. The mechanical properties, such as draw ratio at break and ultimate tensile stress, decrease with dose in ductile samples. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1375–1384, 1999