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Molecular weight distribution and environmental stress cracking of linear polyethylene
Author(s) -
Herman James N.,
Biesenberger Joseph A.
Publication year - 1966
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.760060410
Subject(s) - materials science , environmental stress cracking , molar mass distribution , composite material , ultimate tensile strength , polymer , stress (linguistics) , cracking , polyethylene , fractionation , chromatography , stress corrosion cracking , chemistry , linguistics , philosophy , alloy
Molecular weight distributions of both Phillips and Zieglertype high density polyethylenes were determined following fractionation of the polymer samples using a column elution technique. The Wesslau log normal distribution function was used to describe the distributions of the resins investigated. Resistance to environmental stress rupture of speciments cut from compression molded plaques of these samples was measured by the constant tensile loading procedure. Data are presented showing annealed resins with “broad” molecular weight distributions, characterized particularly by a quantity of low molecular weigt material and a high molecular weight “tail,” to have poorer stress crack resistance than samples having a “narrow” molecular weight distribution. Stress crack resistance of specimens quenched from the melt, however, tends to improve for “broad” distribution resins, while decrasing for those polyethylenes having a “narrow” molecualar weigt distribution. Differences in crystal structure are used to explain the physical bassis for these effects.