Surface modification of melt electrospun polypropylene fibrous film by silicon dioxide gel for high thermomechanical properties

Abstract

In this work, a polypropylene (PP) porous film was made-up by melt electrospinning. The fibrous film was coated by a superthin layer of silicon dioxide (SiO₂) gel. The surface morphology of the SiO₂ gel was decoded by scanning electron microscopy and atomic force microscopy. The SiO₂ gel interface with film, as well as its crystallinity, were characterized by Fourier transform infrared spectroscopy, energy dispersive spectroscopy, and X-ray diffraction. The PP composite film's thermomechanical properties were studied through thermal shrinkage, thermal gravimetric analysis, dynamic mechanical analysis, and an Instron tensile machine with a heating chamber. The results showed that the coated SiO₂ gel network could effectively reduce the PP film's thermal shrinkage by 48.5% without change of crystallinity. The coated SiO₂ gel is capable of enlarging the decomposition temperature range and the storage modulus of the PP film. Meanwhile, it was discovered that, along with the increase of measured temperature, the loads on both pure PP film and PP/SiO₂ gel film decreased under a constant strain, or the tensile strain of both of them was enhanced under the same load. The solid gel network endows the PP electrospun film with relatively higher thermal safety.