Largely enhanced effective porosity of uniaxial stretched polypropylene membrane achieved by pore-forming agent

A simple method for enhancing the effective porosity of the uniaxial stretched polypropylene (PP) membrane through the introduction of a pore-forming agent polyoxyethyleneoctylphenyl-10 (OP-10) was developed. The PP membrane was prepared through melt-compounding, compression molding and subsequent uniaxial tensile process. The microstructures of as-prepared samples and pore morphologies of the stretched membranes were investigated. The effective porosity was measured through soaking method using ethanol as the soaking liquid. The results showed that many initial pores were successfully introduced into the samples with the addition of OP-10. OP-10 leaded to the decrease of the crystallization temperature, melting temperature and crystallinity of PP samples as obtained. The effective porosity increased with increasing tensile strain, and largely enhanced effective porosity was achieved for the samples with the relatively high content of OP-10. This work provides an effective method for the preparation of the stretched PP membrane with high effective porosity by combining the incorporation of initial pores with the uniaxial stretching.