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Stress cracking and photodegradation behavior of polycarbonate. The combination of two major causes of polymer failure
Author(s) -
Timóteo G.A.V.,
Fechine G.J.M.,
Rabello M.S.
Publication year - 2008
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.21067
Subject(s) - environmental stress cracking , photodegradation , materials science , polycarbonate , crazing , ultimate tensile strength , composite material , stress (linguistics) , polymer , scanning electron microscope , stress relaxation , degradation (telecommunications) , stress corrosion cracking , creep , corrosion , organic chemistry , chemistry , philosophy , photocatalysis , computer science , catalysis , telecommunications , linguistics
This work investigates the effects of photodegradation on the environmental stress cracking resistance of polycarbonate (PC). Injection molded samples were exposed to the ultraviolet (UV) light for various times in the laboratory prior to solvent contact. The bars were then stressed with two different loads in a tensile testing machine under the presence of ethanol. During this period, the stress relaxation was monitored and, after unloading, the ultimate properties were evaluated. Complementary tests were done by size exclusion chromatography, UV–visible spectroscopy, scanning electron microscopy, and light microscopy. The results indicated that ethanol causes significant modification in PC, with extensive surface crazing as well as reduction in mechanical properties. The previous degraded samples showed a higher level of stress relaxation and a greater loss in tensile strength in comparison with the undegraded ones. The synergist action of photodegradation and stress cracking in PC may be a consequence of the chemical changes caused by oxidation. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers