유화주합을 통한 PS/clay 나노북합체의 합성 및 유변 물성

초록

Polymer/clay nanocomposites are widely used in various applications such as transportation, construction and consumer products, because they show substantial enhancements of thermal, mechanical, and flammability properties compared to the pristine polymers. Polystyrene (PS) is one of the most popular and widely-used polymers. Severial methods of PS-clay hybrid nanocomposite were invested by many researchers. One of useful method is in situ thermal polymerization. In this study, PS/organophilic montmorillonite (OMMT) nanocomposites were prepared via emulsion polymerization. It has been already reported that the molecular weight of PS via emulsion polymerization is higher than other process. Organic styrene monomer was first intercalated into the interlayer regions of organophilic clay hosts, followed by a typical emulsion polymerization with surfactant and initiator. For enhancement of clay dispersion, ultrasonic process is appplied in the emulsion states. To study the effect of clay loading, we prepared PS/OMMT nanocomposites with various clay contents and examined material properties with increasing clay content. The thermal stability of PS/OMMT was investigated by thermogravimetric analysis(TGA). The enhanced thermal properties of nanocomposites were measured by differential scanning calorimetry (DSC) and indicated that the glass transition. Increase in the decomposition temperature was indicated as increases of clay content. The X-ray diffraction indicated no peak in the nanocomposites. Transmission electron microscopy showed that emulsion polymerization of PS in the presence of clay to be partially exfoliated nanocomposites. Moreover, the composite material was measured with Fourier transform Infrared Spectroscopy (FT-IR) and energy dispersive spectroscopy (EDS). The rheological properties of the PS/OMMT nanocomposites were also measured via a rotational rheometer with a parallel plate geometry, after melt palletizing process.