Hierarchical structure and properties of high‐density polyethylene (HDPE) microporous films fabricated via thermally‐induced phase separation (TIPS): Effect of presence of ultra‐high molecular weight polyethylene (UHMWPE)

Abstract

In this study, HDPE/UHMWPE microporous films were prepared by blending UHMWPE and HDPE with DOP as the diluent via thermally-induced phase separation (TIPS) method. Morphological studies showed that the phase separation mode of the mixed systems was hardly changed in the presence of UHMWPE. Both average pore size and porosity of the blend films increased firstly and then decreased with increasing UHMWPE content. When UHMWPE content reached 1.5 wt%, both porosity and average pore size of the film reached their maximum values (with a porosity of 84.8% and an average pore size of 0.79 μm). The addition of UHMWPE was found to not only enhance the thermal stability of the HDPE/UHMWPE blend films, but also greatly reduce their thermal shrinkage rate as well as the closed cell temperature, which made the diaphragms containing UHMWPE have good prospect for the application in lithium-ion batteries (LIBs).

Shish‐kebab structure evolution of HDPE/UHMWPE during hot drawing

“…Blended materials can integrate the individual advantages of HDPE and UHMWPE, such as high strength and easy processing of HDPE, as well as the wear resistance and biocompatibility of UHMWPE, thereby achieving enhanced physical and chemical properties 4–6 . In many processing methods of HDPE/UHMWPE blends (such as extrusion, spinning, injection molding and blow molding), it is impossible to avoid the introduction of a flow field when the melt is transported and formed 7–13 . For a specific polymer material system, the flow field experienced by the melt during processing is the main factor determining the material morphology and final properties.…”

“…[4][5][6] In many processing methods of HDPE/UHMWPE blends (such as extrusion, spinning, injection molding and blow molding), it is impossible to avoid the introduction of a flow field when the melt is transported and formed. [7][8][9][10][11][12][13] For a specific polymer material system, the flow field experienced by the melt during processing is the main factor determining the material morphology and final properties. Consequently, investigating the crystallization mechanism of polymers under the influence of flow fields holds substantial importance for comprehending the physics of polymer processing and for the deliberate regulation of polymer morphology and evolution.…”