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Natural and artificial weathering of polyethylene plastics
Author(s) -
Howard J. B.,
Gilroy H. M.
Publication year - 1969
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760090409
Subject(s) - weathering , materials science , carbon black , dispersion (optics) , polyethylene , composite material , low density polyethylene , particle (ecology) , optics , natural rubber , geology , oceanography , physics , geomorphology
Empirical test data on low‐density polyethylenes exposed to the elements for very long times are compared with results on samples of the same materials subjected to artificial “weathering” in a modified carbon arc machine. The test results conform to the expression\documentclass{article}\pagestyle{empty}\begin{document}$$ t_a = B + t_n^k $$\end{document}where t a is hours of accelerated weathering, t n years of natural exposure, and the constants B and k have values of 150 and 2.4, respectively, for the materials and test conditions involved. Earlier results are confirmed in that optimum weather resistance is found to depend on good dispersion of a fine‐particle black. Protection improves with concentration up to the limit of about 5% by weight imposed by degenerative effects on mechanical properties from higher loadings of the fine channel blacks. Dependence of weatherability on molecular weight (melt index) is noted.