[The structural basis for fatigue failure initiation in glassy polymers]. Progress report, July 1991--October 1993
In this period efforts were devoted to studying the microstructural elements characterizing fatigue failure initiation, their evolution as a function of fatigue history, and role of external variables. Materials studied include polycarbonate (PC) and its derivatives with different relaxation behaviors, and epoxies with different cross-link densities. The majority of the studies were devoted to PC. Techniques used included mechanical testing, volumetry, density, DSC, x-ray scattering, positron annihilation, TEM, etc. Results suggest that craze initiation starts with expansion of ``elementary`` voids; that fatigue failure initiation in bulk, amorphous PC is generation of stable voids or ``proto-crazes``; that sizes of initial voids are generally in the range of tens of nanometers; that growth of proto- crazes into mature crazes occurs through expansion of voids and generation of new ones perpendicular to fatigue stress; and that fatigue craze initiation in bulk, amorphous PC even at below T{sub g} may involve disentanglement of polymer chains.
- Research Organization:
- Univ. of Michigan, Ann Arbor, MI (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-88ER45366
- OSTI ID:
- 10167559
- Report Number(s):
- DOE/ER/45366-6; ON: DE94015415; BR: KC0201020
- Resource Relation:
- Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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