Thermal and Mechanical Properties of Chitosan/SiO2Hybrid Composites

Abstract

Chitosan-silica (CSSi) hybrid films have been fabricated by sol-gel process using tetraethoxysilane (TEOS) as precursor. The structure of the resulting hybrid has been characterized by Fourier transform infrared spectroscopy (FTIR). Fracture surface has been revealed through a field emission-scanning electron microscopy/energy dispersive spectrometer (FE-SEM/EDS) to probe the dispersion degree and the size ofSiO2particle. Study of morphology using a SEM micrograph and the High Resolution Transmission Electron Microscopy (HRTEM) images of the nanocomposite films suggests that theSiO2nanoparticles are within the range of 2–7 nm in diameter and are uniformly dispersed in the polymer matrix. Thermal properties of these composite materials have been studied as a function of silica, indicating that thermal stability of the chitosan film is enhanced. Dynamical mechanical thermal analysis (DMTA) has been carried out to measure the shift in the glass transition temperature (Tg) of the composites from the maxima of theαtransition curves. The glass transition temperature and the storage modulus show an increase with increasing silica content. The maximum increase in theTgvalue, that is,159.37∘C,is seen with 30 wt% silica. A gradual increase of 3.0 GPa in the modulus relative to the pure polymer is observed.