Effect of mandrel rotation speed on morphology and mechanical properties of polypropylene pipes produced by rotational shear

To research the role of mandrel rotation speed on the morphology and mechanical properties of polypropylene (PP) pipes, a self-made rotational shear system (RSS) was applied in this study to manufacture plastic pipes with improved hoop tensile strength through applying hoop shear on the pipes using a rotational mandrel. Morphology study results indicated that different morphologies of the PP pipes were produced when the mandrel rotated at 0 rpm, 2 rpm, 4 rpm, 6 rpm, 8 rpm and 10 rpm. The tensile strength and elongation at break of the pipes were found to increase rapidly with the rotation speed and the properties peaked at 6 rpm. At this speed, the tensile strength and elongation at break increased by 4.1% and 727%, respectively. The high mechanical and thermal performance of the pipe produced at 6 rpm was attributed to the grains begin to refine and the thickness of amorphous region increases throughout the pipe wall.