Porous Ultra‐High Molecular Weight Polyethylene Membrane Prepared by One‐ and Two‐Step Biaxially Stretching Method

ABSTRACT Volatile decalin as a solvent to prepare porous UHMWPE membrane is explored in this paper. Capillary force will lead to pore collapse, so decalin cannot be volatiled in the drawing process, and it must be removed as much as possible before biaxially stretching. However, without lubricating of solvent, the orientation of the polymer chain becomes difficult. So, after the investigation of one‐step drawing conditions, including the drawing temperature, speed, ratio, and heat‐setting temperature, the best prepared membrane (HT135) has a low tensile strength of 75.6 MPa but a high Gurley value of 49.8 s/100 mL and porosity of 61.7%. Then, a two‐step drawing method was proposed to fabricate the UHMWPE membrane. In 2nd drawing process, the raised temperature will improve the movement of the polymer chains. After 2nd drawing, the membrane (1.2UPE/2) tensile strength is increased to 187.0 MPa and has a Gurley value of 72.5 s/100 mL and porosity of 36.7%. Moreover, the addition of a nucleating agent and using high molecular UHMWPE resin are beneficial for the preparation of higher tensile strength and uniform morphology membranes, respectively.