ISSN:
1435-1528
Keywords:
Stress dilatometry
;
polyethylene
;
stress relaxation
;
Grüneisen parameter
;
physical ageing
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Abstract This paper presents the results of an experimental study of the stress relaxation behaviour of PE where the focus was on determination of the volume changes taking place during the relaxation process. The dimensions of the samples were followed using a specially designed non-disturbing extensometer. The extensometer data were confirmed in experiments where the volume was measured with a specially designed liquid stress dilatometer. The bulk of the results was obtained with LDPE and LLDPE. High density polyethylene was shown to behave similarly. The decrease in volume, corresponding to an increasing Poisson's ratio, during relaxation was approximately linear with log time. Volume vs. stress diagrams were linear; the values of the apparent bulk modulus calculated from them were only slightly higher than those obtained from the stress-strain curves. Grüneisen parameter was measured and compared with reported values. Possible similarities between the volume change during stress relaxation and that occuring during the process of physical ageing are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00398438
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