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Impact resistance and secondary transitions
Author(s) -
Hartmann Bruce,
Lee G. F.
Publication year - 1979
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.1979.070231219
Subject(s) - charpy impact test , materials science , composite material , polycarbonate , scanning electron microscope , liquid nitrogen , brittleness , izod impact strength test , fracture (geology) , atmospheric temperature range , glass transition , polymer , chemistry , toughness , thermodynamics , physics , organic chemistry , ultimate tensile strength
Instrumented Charpy impact measurements were made on polycarbonate from liquid nitrogen temperature to room temperature. The polymer had a transition from brittle fracture to ductile failure at −130°C. Scanning electron micrographs of the fracture surfaces did not correlate with the secondary transition or test temperature. A Fourier analysis of the impact pulse covers a wide range of frequencies, but the dominant frequencies at room temperature are below 200 Hz. Time–temperature superposition shows that the secondary transition occurs over a broad frequency range centered at 7 MHz at room temperature. Impact strength and the secondary transition (at impact frequency) both have a maximum value around −75°C.