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Macroscopic, microscopic and molecular aspects of fracture in polymers
Author(s) -
Devries K. L.,
Hornberger L. E.
Publication year - 1989
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19890270109
Subject(s) - materials science , polymer , composite material , polystyrene , polycarbonate , fracture (geology) , residual stress , stress (linguistics) , polyethylene , kevlar , quenching (fluorescence) , amorphous solid , composite number , chemistry , crystallography , philosophy , linguistics , physics , quantum mechanics , fluorescence
The distribution of stress at macroscopic and molecular levels can dramatically affect mechanical properties. This paper explores both these aspects. In the first part, quenching operations for polycarbonate and polystyrene were shown to develop favorable residual stresses as well as structural alterations (as manifested by changes in density, hardness, DSC results, etc.). The changes in these glassy polymers can be accompanied by as much as an order of magnitude increase in impact strength and fatigue life. In the other phase of our study, various analytical methods were used to investigate phenomena associated with fracture in oriented semi‐crystalline polymers. In the studies reported here, the combined effects of stress and environmental agents on mechanical strength of nylon, polyethylene, and Kevlar fibers were measured. These results, in conjunction with investigations of bond rupture kinetics, suggest that fracture in these materials involve thermally activated chain scission in which the activation energy is aided by stress and the chemical environment. Different mechanisms appear to dominate fracture in spherulitic forms of chemically similar polymers.