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Stress Cracking and Photodegradation: The Combination of Two Major Causes of HIPS Failure
Author(s) -
Timóteo G.A.V.,
Fechine G.J.M.,
Rabello M.S.
Publication year - 2007
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200751218
Subject(s) - photodegradation , materials science , ultimate tensile strength , composite material , stress (linguistics) , polystyrene , environmental stress cracking , stress relaxation , scanning electron microscope , degradation (telecommunications) , cracking , creep , chemistry , stress corrosion cracking , polymer , organic chemistry , corrosion , telecommunications , linguistics , philosophy , photocatalysis , computer science , catalysis
Summary: This work investigates the effects of photodegradation on the stress cracking resistance of high impact polystyrene (HIPS). Injection moulded samples were exposed to the ultraviolet light for various times in the laboratory prior to solvent contact. The bars were then stressed with several different loads in a tensile testing machine under the presence of several types of alcohols (mostly butanol). During this period, the stress relaxation was monitored and, after unloading, the ultimate properties were evaluated. Complementary tests were done by size exclusion chromatography, and scanning electron microscopy. The results indicated that both photodegradation and butanol causes significant modification in HIPS properties, with reduction in mechanical properties. The previously degraded samples showed a higher level of stress relaxation and a greater loss in tensile strength in comparison to the undegraded ones. The synergistic action of photodegradation and stress cracking in polystyrene may be a consequence of the chemical changes caused by oxidation and the reduction in molecular sizes.