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Analysis of deformation processes in glassy polycarbonate using internal friction measurements during a tensile test
Author(s) -
Parisot J.,
Rafi O.,
Choi W. J.
Publication year - 1984
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.760241108
Subject(s) - materials science , polycarbonate , strain rate , composite material , ultimate tensile strength , deformation (meteorology) , torsion (gastropod) , tensile testing , steady state (chemistry) , flow stress , stress (linguistics) , mechanics , medicine , linguistics , chemistry , philosophy , surgery , physics
Internal friction has been measured by torsion at 1 Hz during tensile tests performed on glassy polycarbonate at room‐temperature. Steady‐state flow and transient effects have been studied during continuous tensile tests and strain‐rate changes. During steady‐state, internal friction and flow‐stress vary in a similar way with strain‐rate. But during transients, internal friction varies continuously while flow‐stress passes through a maximum (or a minimum). These results are interpreted assuming that non‐elastic deformation of glassy polymers requires some microscopic discontinuous processes such as motion of defects. Two parameters are considered: the velocity v and the density ρ of mobile defects. Assuming that the former is directly related to the flow stress, it has been shown that internal friction is related to the density of mobile defects ρ. This feature is used to interpret the different stages of a tensile test curve. Activation volumes for both velocity and density of mobile defects are calculated from experimental data.