Polyvinylidene fluoride/ultra-high molecular weight polyethylene blend microporous membrane and preparation method thereof

A preparation method of a polyvinylidene fluoride/ultra-high molecular weight polyethylene blend microporous membrane, including the following steps:

• S1:
• drying ultra-high molecular weight polyethylene at 60° C. for 2-3 h, and polyvinylidene fluoride at 90° C. for 2-3 h;
• S2:
• mixing the polyvinylidene fluoride and the ultra-high molecular weight polyethylene prepared in S1 together with an antioxidant and a diluent system, then stirring for 1-2 h at room temperature to obtain a uniformly dispersed suspension;
• S3:
• feeding the suspension prepared in S2 into a twin-screw extruder with 6 heating zones heated individually, wherein the temperature of each heating zone from 1 to 6 are, in order, 130° C., 140° C., 160° C., 175° C., 190-220° C., 200-230° C., and the outlet temperature is 200-250° C.;
• and injecting the cast membrane gel extruded from the outlet directly into a metal mold for injection molding;
• wherein the mold temperature and the outlet temperature of the twin-screw extruder are the same, and the cavity surface of the mold has micro-prism array structure;
• and then cooling the mold with the cast membrane gel in aqueous medium of 0-100° C. to obtain a nascent gel membrane;
• S4:
• drying the nascent gel membrane prepared in S3 in a freeze dryer for more than 12 h after removal of the diluent by extraction, to obtain a polyvinylidene fluoride/ultra-high molecular weight polyethylene dry blend microporous membrane.