Retraction of Cold-Drawn Polyethylene: Influence of Lamellar Thickness and Density

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Abstract
The role of crystal morphology in the retraction of oriented linear polyethylene was studied utilizing samples crystallized under conditions controlled to vary, separately, lamellar crystal thickness and density. Samples were oriented in a sample shear deformation to a strain of 4.0 prior to measuringretraction tendency in creep‐ and relaxation‐type tests. Characterizations of specimens were made using wide‐ and small‐angle x‐ray techniques. The specific morphological variations were chosen to test the hypothesis that a long‐range elastic restoring force can originate in conjunction with deformation of lamellar crystals and the consequent increase in lamellar crystal surface area and surfacefree energy. The results support this hypothesis.