Syndiotactic polystyrene / organophilic clay nanocomposites prepared by melt intercalation : synthesis and materials properties

Abstract

Polymer nanocomposite are particle-filled polymer where at least one dimension of the dispersed particle is on the nanometer scale. In this paper, syndiotactic polystyrene (sPS) / organophilic clay nanocomposite was fabricated by melt intercalation method. The fabrication method proper to high temperature processing of sPS was proposed and the microstructure and mechanical and thermal properties of fabricated nanocomposites were investigated. In chapter 2, we investigated the microstructure and materials properties of sPS / organophilic clay nanocomposites prepared by direct melt intercalation. In order to avoid the thermal instability problem of organophilic clay, we fabricated more thermally stable organophilic clay, which does not decompose at high processing temperature of sPS. Using the newly synthesized organophilic clay, we could fabrication sPS nanocomposite by direct melt intercalation. XRD and TEM results showed that this nanocomposite is an intercalated nanocomposite. From the non-isothermal crystallization, it is known that the overall crystallization rate of the nanocomposite slightly decreases with clay content. This result is related with the clay dispersion and physical hindrance of organic modifiers. And the growth of crystal seems to be hindered by the presence of clay layers. Nanocomposite showed the enhanced mechanical and thermal properties compared with the matrix polymer. In chapter 3, sPS nanocomposites prepared by stepwise melt intercalation was investigated. In this method, amorphous styrenic polymer was introduced to avoid the thermal instability problem of organophilic clay. Using poly(styrene-co-vinyloxazolin) (RPS) as amorphous styrenic polymer and thermally stable organophilic clay, we could fabrication sPS nanocomposite. XRD and TEM results showed that this nanocomposite has an exfoliated structure. The dispersion of clay layers of this system is better than that of nanocomposites prepared by direct melt intercalation. Previously...