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The morphological consequences of annealing high‐density polyethylene in solvents
Author(s) -
Blackadder David A.,
Keniry John S.
Publication year - 1972
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/app.1972.070160517
Subject(s) - polymer , crystallinity , sorption , solvent , polyethylene , materials science , chemical engineering , permeation , polymer chemistry , molecule , xylene , annealing (glass) , high density polyethylene , chemistry , organic chemistry , membrane , composite material , benzene , adsorption , biochemistry , engineering
When a semicrystalline polymer imbibes solvent molecules at near‐ambient temperatures it is very probable that the crystalline regions are not affected. The noncrystalline regions swell to accommodate the solvent and may also undergo structural changes which are not reversed on removing the solvent. If this happens, the sorptive capacity of the polymer is permanently changed. Pretreating a polymer membrane with liquid solvent has the same effect on sorption measurements as pretreatment with the corresponding saturated vapor only when special precautions are observed. High‐density polyethylene films were used throughout the investigation, and p ‐xylene was the organic permeant. Numerous measurements of sorption and permeation rates were made, and the results are discussed in terms of a new model for the behavior of noncrystalline chains in a semicrystalline polymer. The shorter tie molecules running between the crystalline lamellae appear to be of crucial importance, and slight modification of these may have a large effect on the sorptive capacity of the sample as a whole. The possibility of solvent molecules clustering in the swollen polymer is considered in an Appendix.