The effects of process parameters on the mechanical properties of die drawn polypropylene

This study investigates the effects of important process parameters on the mechanical behavior of die drawn polypropylene (PP). A single-stage hot die drawing test rig designed particularly for this purpose was used to produce oriented PP rods. Tensile and compression tests were conducted on the die drawn rods. The influence of drawing process parameters such as nominal draw ratio, drawing speed and drawing temperature on drawing load, final area reduction (actual draw ratio), elastic moduli and yield strength was studied. The tensile test results show that tensile modulus of elasticity and yield strength are improved substantially by increasing the drawing ratio. Further improvement can be obtained by increasing the drawing speed. However, increasing the drawing temperature reduces the tensile strength and modulus over the range tested. In contrast, the compression modulus and yield strength both increased with processing temperature, but decreased with processing speed.