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Residual stresses and toughness of polycarbonate exposed to environmental conditions
Author(s) -
Ram A.,
Zilber O.,
Kenig S.
Publication year - 1985
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.760250911
Subject(s) - materials science , polycarbonate , composite material , residual stress , ultimate tensile strength , toughness , embrittlement , polymer , compressive strength , mold
The role of the size and type of residual stresses and their distribution in the interior of polycarbonate mold‐injected test bars was studied, in view of the interrelationship between toughness and thermal or environmental history. The large thermal gradient during solidification of the polymer in the mold builds up compressive stresses near the wall and tensile stresses in the core. Annealing followed by slow cooling may reverse the type of stresses near the surface, while quenching augments the compressive stress. The latter stress near the wall is responsible for the extraordinarily high impact strength of polycarbonate. Exposure to the atmosphere and immersion in hot water may affect the distribution of residual stresses and thus contribute to the embrittlement of the originally tough polymer. The importance of molecular weight and polymer stabilization is elucidated.