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Effect of heat pretreatment and strain rate on tensile properties of polycarbonate sheet
Author(s) -
Yokouchi Mitsuru,
Kobayashi Yasuji
Publication year - 1981
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.1981.070260205
Subject(s) - crazing , materials science , polycarbonate , ultimate tensile strength , differential scanning calorimetry , composite material , glass transition , strain rate , brittleness , tensile testing , polymer , thermodynamics , physics
The effects of heat pretreatment and ambient gas (air and vacuum) on selected properties of the polycarbonate sheet have been studied. Changes in tensile properties as functions of heat pretreatment temperature (up to 160°C) and strain rate (wide range of 1.7 × 10 −4 − 13.1 m/sec = 0.29 − 2.3 × 10 4 %/sec) were determined and these are discussed in relation to changes in differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) data. The performance characteristics of the present tensile testing are obtained over a wide range of extension rates without changing the mode of deformation and the shape of the test pieces. It was suggested from the experimental results that heat pretreatment below the glass transition temperature ( T g ) causes ordered molecular domains to grow on the free surfaces of the sheet, consisting of thermally deteriorated macromolecules and possessing lower crazing stresses (exhibiting more brittle mechanical responses, leading to the decrease in breaking strain and energy). The effect of annealing above T g on the tensile properties, and on the results of DSC and GPC, could not be precisely understood.