Structure and properties of melt-stretching polypropylene/silicon dioxide compound microporous membrane

Abstract

To improve the strength and modulus of polypropylene (PP) microporous membrane, the nano-silicon dioxide (SiO2) was introduced and the influence of SiO2 content on the structure and properties of initial precursor film and stretched microporous membrane was investigated. It was found that with increasing SiO2 content to 2%, the crystalline orientation degree of precursor film was decreased from 0.41 to 0.32, but the elastic recovery value did not change much. The mean pore diameter of the stretched microporous membrane was increased from 28.3 to 32.5 nm. The Gurley value (characterizing the air permeability) only decreased from 200 to 194 s. The tensile strength and elastic modulus were increased by 33.3 and 72.0 MPa, respectively. But when the SiO2 content was 10%, the air permeability of stretched microporous membrane was apparently decreased by 21.5%. Compared with that of microporous membrane without SiO2, the tensile strength was increased by only 1.6 MPa. It was concluded that the introduction of 2% content of SiO2 resulted in the improvement of mechanical properties, at the same time did not deteriorate the pore structure and properties of PP microporous membrane. POLYM. COMPOS., 37:2684–2691, 2016. © 2015 Society of Plastics Engineers