Two New Approaches to Toughness Characterization of Polyethylene
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Abstract
A new mechanistic approach is applied to characterizing toughness of low-density polyethylene (LDPE) in ductile fracture, introduced in double-edge-notched tensile (DENT) test. Three mechanisms were involved in the new approach, i.e. fracture surface formation, necking and shear plastic deformation. The specific energy density for the fracture surface formation, determined from the new approach, was found to be about 12% higher than that from the original EWF method, and the specific energy density for necking is close to that determined from simple tensile test. Ultra-high-molecular-weight polyethylene (UHMWPE) was also characterized using DENT test. However, it was found that its fracture behavior cannot be described using the original EWF method, and since necking does not occur, nor by the new mechanistic approach. As a result, a modified EWF method was developed. To justify validity of the modified EWF method, a formulation of energy balance equation was established.