The Control of Pore Size in Polypropylene/Paraffin Mixtures Using Intercalated Guest SiO 2 Particles

Abstract

This paper discusses the control of fine layer-like pores in high crystallinity polypropylene (PP) films from a mixture of liquid paraffin and silica particles (SiO₂) by rolled compression. Mixtures with various ratios were hot rolled, and then paraffin was extracted in organic solvents. The fine structure of these films was investigated by measuring the apparent specific volume, the surface area using the after nitrogen gas adsorption-desorption method, and small angle X-ray scattering (SAXS). Polythene films with mixing ratios with paraffin from 0.10 to 0.50 w/w showed layer-like pores using rolling ratios of 10 to 30 at 115°C. A wide surface area of 160 m²/g was achieved by rolling the films with mixing ratios 0.17 to 0.10 at rolling ratios of 20 to 30. The SiO₂ guest was randomly dispersed in paraffin. It was suggested that a regularly spaced structure of polypropylene layers (host) and layer-like pores of 9 nm and 10.5 nm thick, respectively, is formed at rolling ratios of 25 to 30. The SiO₂ plays an important role of intercalation through the polypropylene thin layers, oriented by rolled compression.