Advantage of preserving bi-orientation structure of isotactic polypropylene through die drawing

• Main Authors: Lyu, D., Sun, Y.Y., Lai, Y.Q., Thompson, Glen P., Caton-Rose, Philip D., Coates, Philip D., Lu, Y., Men, Y.F.
• Language: en
• Published: 2021
• Subjects: Die-drawing; Isotactic polypropylene; Solid-state deformation; Bi-orientation; WAXD
• Online Access: http://hdl.handle.net/10454/18318

Yes === The isotactic polypropylene (iPP) usually shows a unique parent-daughter lamellae structure in which the parent and daughter lamellae are against each other with a near perpendicular angle (80° or 100°). Inducing a high fraction of oriented cross-hatched structure in iPP during processing is desirable for designing the bi-oriented iPP products. We processed a commercial iPP via tensile-stretching and die-drawing to evaluate the structural evolution of oriented parent-daughter lamellae. It turned out that the die-drawing process had an advantage in attaining a high fraction of oriented cross-hatched structure of iPP, as compared to the free tensile stretching. Besides, the presence of α-nucleating agents affected the formation of oriented parent-daughter lamellae in the die-drawn samples whereas such influence diminished in the free stretched ones. It was found that the confined deformation inside the die led to the well-preserved oriented cross-hatched structure in the die-drawn iPP. === This work was financially supported by the National Natural Science Foundation of China (Nos. 21704102, U1832186, and 51525305), Newton Advanced Fellowship of the Royal Society, United Kingdom (No. NA150222) and ExxonMobil Asia Pacific Research & Development Co., Ltd.