The investigation of nanocomposites of polystyrene obtained with temperature control

Polymers are materials of very high molecular weight that are found to have multifarious applications in modern society. Polymers are obtained through the chemical reaction of small molecular compounds called monomers. Polymeric materials usually have high strenght, possess a glass transition temperature, exhibit rubber elasticity and have high viscosity as melts and solutions.In our contamprorary, polymer technology has become an important part of the industry. To obtain a product with desired properties, system variables and ambient conditions need controlling.Nanocomposites are materials that are created by introducing nanoparticulates into a microscopic sample material. Organic-inorganic nanocomposites have attracted a lot of interests in recent years since they usully occupy the combined properties of organic polymers and inorganic materials. They show better physical properties such as thermal, mechanical and barrier properties because of the much stronger interfacial force between the well dispersed nanometer-sized domain than the conventional polymer/filler composites. Inorganic particles such as clay, SiO2 and TiO2 are widely used for preparation of polymer nanocomposites.In this project, the objective was to synthesis and characterization polystyrene (PS)/silica nanocomposites. Polymer/silika nanocomposites were prepared by two methods as in situ polymerization and melt intercalation. Polymerization reaction occured in the semi-batch polymerization reactor by free radical polymerization method. During the polymerization, system temperature was kept under control with self-tuning PID controller and was followed by VisiDAQ program. To find optimal tuning parameter of controller, genetic algorithm was used. In this study, samples were taken at specific intervals, monomer conversion and molecular weight were calculated. The molecular weight of polystyrene were determined by viscosity method. Characterization phase of nanocompozite materials structural, thermal, mechanical and surface characterization properties were examined. For the defining of thermal properties thermogravimetric analysis (TGA), for surface characterization properties scanning electron microscopy (SEM) and for structural analysis fourier transform infrared spectroscopy (FTIR) was used. Hardness measurements were used in determining the mechanical properties. Characterization results showed, the thermal and mechanical properties changed depending on silica ratio. Mechanical and termal resistance increase with the amount of silica increases. In surface characterization it was determined that distribution of silica particles were not homogeneous and there was aggregations. Nanocomposite production methods were compared in the ligth of characterization works and it is determined that specificatiın of nanocomposites which are produced with melt intercalation method are better than the other.