The Synthesis of Epoxy Polyuretheane -Silica Nanocomposites

Nanoparticles are mixed with polymers and create nanocomposites which have new properties. In order to disperse nanoparticles in the polymer, first, their surface is stabilized by silane coupling factor. This prevents nanoparticles agglomeration and improves the compatibility between nanoparticles and polymer which enhances many of their properties. In this research, the epoxy polyurethane-nanosilica nanocomposite is synthesized in situ. To synthesize this nanocomposite, SiO2 nanocomposites are prepared in N,N-dimethylformamid (DMF) through Stober method and then their surface is modified by 3-Methacryloxypropyl triethoxysilane (MPS) and they were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). Novolac epoxy resin (EP) was prepared by the reaction of epichlorohydrin and Novolac in the presence of soda (NaOH) and epoxy acrylate resin (EA) was synthesized based on the ring opening reaction of Novolac epoxy resin and methyl methacrylate acid was synthesized in the presence of tetrabutylamonium bromide (TBAB) catalysis and characterized by FT-IR spectroscopy and HNMR. Then, mps-SiO2 modified nanoparticles were exposed to electrosonic waves in DMF solvent and monomers of acrylate (styrene, butyl acrylate and synthesized acrylate epoxy) + initiator of azobis isobutyro nitrile (AIBN) were added to the nanoparticle uniformly and dropwisely and in situ polymerization occurred. Now, the nanoparticle is in a polymer capsule which is known as the coreshell structure. 1 and 3 percent of core-shell nanoparticles were added to the polyurethane base. Thermal properties of synthesized nanoparticles were studied by thermogravimetric analysis (TGA) and characterized by FT-IR spectroscopy and scanning electron microscopy (SEM). Results showed that adding core-shell nanoparticles up to 3 percent led to the improvement of thermal resistance of polyurethane [1].