Effect of Long‐Chain Branched High‐Density Polyethylene on Shear‐Induced Crystallization of Polypropylene

In the present study, we investigated the impact of a long‐chain branched high‐density polyethylene (HDPE‐B) on the flow‐induced crystallization of PP as compared with the impact of a linear high‐density polyethylene (HDPE‐L). Although both HDPE samples acted as crystallization nuclei for PP during cooling at 30°C min −1 , the difference in the nucleating activity between HDPE‐B and HDPE‐L was significant after shear. Well‐developed extended‐chain crystals formed in the HDPE‐B at high temperatures after shear, and they markedly promoted the crystallization of the PP. Consequently, the addition of HDPE‐B provided a high level of orientation of the PP chains. Considering that chain orientation results in a high modulus, HDPE‐B is an efficient modifier for PP.