Preparation Of Polystyrene/Silica Nanocomposite Latex And Its Nanocomposite Materials

Polymer nanocomposite is a branch of composites,which has a wide range of applications in medicine,textile,cosmetics,food packaging,optoelectronic devices,aerospace and catalysis.Compared to the traditional composite materials,the difference is that the nano filler has numerous nano effect and exhibit unique features.Nano composite material not only in the heat resistance and mechanical strength is improved,but also in the conductive and magnetic,antibacterial,solvent resistance,flame retardant exhibit unique features.The properties of nanocomposites depend on the size of nanoparticles and the interaction between two phases.Due to the large specific surface area and volume effect of nanoparticles,the particles are dispersed based on several agglomerated particles in the polymer matrix.The surface modification of nanoparticles can both raise the dispersion and the surface organic components.The modification process can be performed through two methods: the first one is the adsorption or reaction with small molecule modifiers,such as surfactants,silane coupling agent.The second one is grafting polymer chains with covalent bond.In this paper,the silane coupling agents,vinyl trimethoxy silane,were firstly adopted to modify the silica surface for carrying the reactive functional groups.In addition,the graft polymerization of styrene monomer on the silica surface was realized by emulsion polymerization for improving the dispersion of nanosilica.The grafting coupling agents and polystyrene chains on the silica surface were detected by Fourier Transform Infrared(FTIR)spectroscopy.The grafting content of coupling agents on the silica surface was measured by thermogravimetric analysis(TGA).The influence of emulsifier concentration,initiator concentration and silica and monomer to water ratios on particle size distribution of the nanocomposite latex was investigated.The particle size distribution was broadened with the elevator of emulsifier concentration.The particle size distribution firstly narrowed and then broadened with the increase of silica and monomer to water ratios and initiator concentration.The narrow distribution could be controlled in an appropriate silica and monomer to water ratio and an initiator concentration of 1/15 and 2 wt%,respectively.From the evaluation of transmission electron microscopy(TEM)micrographs and dynamic light scattering(DLS)measurement,it was proved that the nanocomposite latex did not have all sphere-like shape,but contained tiny amounts of irregular bodies.The formation mechanism of polystyrene-encapsulated silica nanoparticles was discussed based the analysis of particle size and morphology of nanocomposite latex.Polystyrene/silica nanocomposites were fabricated by the addition of polystyrene-grafted silica nanofiller into polystyrene resin by melt compounding.The influence of nanofiller content on the thermal behavior,tensile strength,fracture morphology of nanocomposites and the dispersion of nanosilica within the nanocomposites matrix.With the incorporated of nanofiller content increased,the Tg values of nanocomposites were significantly elevated from 92.5oC to 99.8oC,the thermal decomposition temperature increased from 400.2oC to 432.6oC,the tensile strength increased from 19.4 to 27.9MPa,the balance torque values increased from 9.5 to 16.The fracture surface of nanocomposites and dispersion condition of nanosilica within nanocomposites demonstrated that the dispersion quality and content of nanofiller had an influence on the debonding process of nanofiller from polymeric matrix.