Temperature dependence of essential and non-essential work of fracture parameters for polycarbonate film

Single edge and double edge notched polycarbonate specimens of thickness 0. 375 mm have been pulled to complete fracture at temperatures between 25 and 120 degrees C. Within this temperature range specimens underwent full liga ment yielding prior to final fracture, producing load-displacement curves a t various ligament lengths that were geometrically similar to one another f or a specific geometry. On the basis of these, the method of the essential work of fracture was used to study the effect of temperature on fracture to ughness of polycarbonate film. Results showed that a linear relationship ex ists between specific total work of fracture w(t) and ligament length L ove r the entire temperature range under consideration. The slope of the line, which is referred to as the specific non-essential total work of fracture b eta w(p), increased with increasing temperature. However, the interception at L = 0, which is referred to as the specific essential total work of frac ture w(e), showed little variation with respect to temperature. Change of g eometry affected both values, although the change in beta w(p) was more sig nificant than that of w(e), for which change of no more than 10% was attain ed. Based on the maximum load on the load- displacement curve, w(t) for dou ble edge notched specimens was partitioned into the specific work of fractu re for yielding ttl, and the specific work of fracture for yielding necking /tearing w(nt). Linear relationships were found for both terms as a functio n of ligament length from which the essential (w(e,y), w(e,nt)) and non-ess ential (beta(y)w(p,y), beta(nt)w(p,nt)) related work terms were attained. R esults showed that the yielding related work terms for polycarbonate decrea se, while the necking/tearing related work terms increase, with increasing temperature.