Components of microstrain in polyethylene

Tensile microstrain was measured in high-density polyethylene with a precision of 2 X 10(-7) for strains up to 10(-4) in the temperature range of 17-28 degreesC over a range of strain rates. The total strain was partitioned into three of the following components: (1) elastic, (2) amorphous, and (3) dislocation. Also, their respective dependence on stress was determined. Measurements of the area of the hysteresis loops gave the energy loss per cycle from which the frictional stress on the amorphous flow and the dislocations was determined. Although the amorphous strain originated at zero stress and was dependent on the temperature and strain rate, the dislocation motion was activated above acritical stress and independent of temperature and strain rate within the scope of these experiments. The viscosity of the amorphous flow was determined. The effect of 5 Mrd gamma irradiation on the micro-deformation behavior was not appreciable. About 80 Mrd reduced the amorphous flow by about 30% and increased the stress to activate the motions of the dislocations. (C) 2002 Wiley Periodicals, Inc.