Temperature and weld-line effects on mechanical properties of CPVC

The paper addresses the effects of temperatures ranging from -10 to 70°C and injection molding induced weld line on the mechanical properties of chlorinated-PVC (CPVC) material used in pipe fittings. Yield stress and modulus of elasticity are found to decrease linearly with temperature. Brittle fracture is observed to occur for temperatures below room temperature while ductile fracture occurred at temperatures above 23°C. At temperatures below 50°C, fracture strain increased by small amounts. A large increase of fracture strain occurred between 50 and 70°C. The plastic deformation at these high temperatures is accompanied by considerable necking. The weld-line effect on the monotonic properties of CPVC is studied by comparing the stress-strain curves of weld and non-weld specimens at different temperatures. Brittle failure is observed at all temperatures for specimens containing a weld line. The difference between yield stress of weld and non-weld CPVC is higher at lower temperatures. The weld line factor defined as the ratio of strength with weld line to strength without weld line is determined for all the temperatures of interest.