Tunable β-crystals formation from transcrystallinity to cylindrites at PP/PE interface via using melt penetration engineering

Transcrytallinity plays a critical role in the interfacial crystalline morphology. However, it is rather rare to observe transcrytallinity grown from completely molten surface without using nucleating agent. Herein, we utilize melt penetration engineering to provide a sheared polymeric melt interface in order to tailor interfacial polypropylene (PP) crystalline morphology from beta-transcrystals (beta-TC) to beta-cylindrites. The investigated system containing polymorphic PP as penetrating phase and polyethylene (PE) as penetrated layer were selected. Interestingly, we can clearly observe a continuous and ordered beta-transcrystals (beta-TC) at PP/PE interface and morphological transition from beta-TC to beta-cylindrites upon using higher molecular weight PE as the penetrated melt. Foreign PE surface plays an indispensable role in transcrystallinity formation since only alpha-spherulites were developed during identical PP penetrating PP process. The effects of surface-induced crystallization as well as coupling flow and temperature field have been discussed, in order to offer an insight on interfacial morphological transition. Consequently, melt penetration engineering can provide a facile and scalable route to achieve designed interfacial morphology from beta-TC to beta-cylindrites, which opens a new perspective to develop interfacial crystalline morphology.

Automated summary

Transcrytallinity plays a critical role in interfacial crystalline morphology. Melt penetration engineering is utilized to tailor the interfacial polypropylene (PP) crystalline morphology from beta-transcrystals (beta-TC) to beta-cylindrites. Higher molecular weight polyethylene (PE) as the penetrated melt leads to the morphological transition from beta-TC to beta-cylindrites.