Improvement in the mechanical properties of polyester nanocomposite with nano-silica prepared by sol-gel method

In this research, the sol solutions of silica nanoparticles were prepared by hydrolysis of tetra-methoxysilane (TMOS) in the presence of methanol. Then, Sol containing silica nanoparticles was added to Isophthalic polyester in 0 to 40 weight percent. The prepared nanocomposites were molded and processed at room temperature in the laboratory condition. In this study, the effect of silica nanoparticles and also the effect of secondary post curing temperature on mechanical properties of the polyester nanocomposite were evaluated. Fourier-transform infrared spectroscopy, FT-IR results showed that Si-O-Si bonds are formed in the polyester silica nanocomposites. The results of Tensile test show that the cured samples at room temperature have more strain and less tensile strength in compared with the post curing nanocomposites at 100˚C. The results of Dynamic-Mechanical Analysis (DMA) on the nanocomposite samples containing (20% TMOS) show an increase in glass transition temperature and real modulus (E') by increasing the post curing temperature. In addition, the results of Dynamic light scattering (DLS) and scanning electron microscopy (SEM) indicate that the size of the particles are 35-40 and 53 nm in the (20%TMOS) nanocomposite sample, respectively. However, the size of formed nanoparticles increases to 87 nm with post curing temperature at 100˚C.