Accession Number : AD0656282

Title :   THERMAL STRESS-CRACKING OF POLYETHYLENE II,

Corporate Author : BELL TELEPHONE LABS INC MURRAY HILL N J

Personal Author(s) : Heiss,J. H. ; Lanza,V. L. ; Martin,W. M.

Report Date : 1959

Pagination or Media Count : 13

Abstract : Under comparatively low strains (up to 50 per cent), the high density (0.96 g/ml) polyethylene thermally stress-cracked in essentially uniaxial tension in the same manner as in the helical-wrap test. This is not at variance with the earlier proposed hypothesis involving elastic distortion of spherulites. In both tests the limiting value of strain, as well as the time to failure at various strain levels, was about the same. Further, from approximately 10 per cent strain to 50 per cent strain, there was no significant change in the time to failure. Observations have shown that thermal stress-cracking and heat embrittlement, which is presumably due to gross changes in crystalline texture, are different phenomena. Further testing has substantiated the fact that high density polyethylenes are quite susceptible to thermal stress-cracking, while low density polyethylenes do not appear to be affected. It also appears that thermal stress-cracking can occur in molded parts containing 'frozen-in' strains. (Author)

Descriptors :   (*POLYETHYLENE PLASTICS, FRACTURE(MECHANICS)), THERMAL STRESSES, CRACKS, FAILURE(MECHANICS), STRAIN(MECHANICS)

Subject Categories : Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE