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Residual stress, aging, and fatigue fracture in injection molded glassy polymers I. Polystyrene
Author(s) -
Iacopi A. V.,
White J. R.
Publication year - 1987
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.1987.070330223
Subject(s) - materials science , polystyrene , composite material , residual stress , fracture (geology) , polymer , stress (linguistics) , philosophy , linguistics
Fatigue tests have been conducted on polystyrene bars molded at different pressures and having different post‐molding thermal histories. Fatigue crack propagation rates were not sensitive to molding or thermal history but in unnotched bars initiation seemed to happen more quickly in bars aged for long periods at room temperature or annealed at elevated temperature. Fractographic studies showed that initiation occurred at favored sites and that the skin/core morphology affected crack growth. Prolonged storage of polystyrene bars at −85°C promoted significant physical property changes (stiffness and density). These changes appeared to be at least partly reversible with rapid recovery occurring within the first 24 h after restoring to room temperature.