Effects of nanofillers on morphology and surface wetting of microporous polypropylene composite membranes

Microporous polypropylene (PP) nanocomposite membranes suitable for various applications such as energy storage, water purification, membrane separation, etc., were prepared by melt mixing of polypropylene and natural rubber (NR) subsequently followed by etching of rubber phase. Nanoparticles having spherical shape (Al2O3), irregular shape (TiO2), and 2D platelet morphology (Cloisite 30 B (C–30 B)), were used to the influence of nanoparticles on pore morphology and wetting properties of PP. Morphology of PP membrane was investigated by SEM and TEM analysis and the study reveals that all the prepared membranes possess a co-continuous porous structure with a minimum percentage porosity of 62 ± 2. Mechanical studies showed that the nanoparticles have a significant effect on tensile strength, strain to failure, and Young's modulus. DSC results indicate that the nanoparticles do not make any significant change on the melting temperature of polypropylene. Polarized optical microscopic studies reveal that nanofillers enhances spherulite growth by acting as a heterogeneous nucleating agent. Contact angle measurements using two different test liquids (distilled water and Dimethyl sulfoxide (DMSO)), reveals that Al2O3 added PP exhibits good wettability in both the test liquids. The present studies reveal that the shape, properties, and active surface area of the nanofillers greatly influence the morphological mechanical and wetting properties of microporous PP.