Preparation And Property Investigation Of Secondarily Intercalated Montmorillonite/Polystyrene Nanocomposite

The organized montmorillonite (OMMT) whose distance between lamellas was enlarged was prepared by organization using long chain quaternary ammonium salt. Based on the OMMT, the secondarily intercalated MMT (SMMT) could be obtained from the products of the reaction between the ammonium ion in the OMMT and acrylic acid or maleic anhydride(MAH). The distance between lamella of MMT can be enlarged further and the double bond of acrylic acid or MAH was introduced in by the chemical reaction. As a result, the MMT has become a reactant which is able to take part in polymerization. By the analysis of XRD, IR and TQ the results indicated that not only did the long chain quaternary ammonium salt exchanged the inorganic cation in MMT, but both acrylic acid and MAH were able to react with the ammonium ion in the OMMT.The OMMT/PS and SMMT/PS nanocomposites were respectively prepared by emulsion polymerization. The micro-structure and heat resisting property of the two kinds of composites were tested and compared. The results indicated mat the distance between lamellas of MMT in SMMT/PS nanocomposite was bigger than that in OMMT/PS nanocomposite. The glass transmission of the former composite was greatly changed and was not easily distinguished. The Tg of the later was higher than pure PS by 6℃. The improvement of the former was more than that of the later in heat resisting property compared with pure PS. The results of TEM indicated that SMMT/PS nanocomposite was exfolicated composite. Moreover, the dispersion of MMT in OMMT/PS nanocomposite was worse than that in SMMT/PS nanocomposite. The two kinds of nanocomposites were also respectively prepared by the method of melt intercalation. The effect of quantity of MMT to the mechanical properties of the two kinds of nanocomposites was investicated. The results showed that when 4% (wt) of MMT was added, the impact strength of the SMMT/PS nanocomposite was a little higher than that of pure PS, but inverse to the OMMT/PS nanocomposite. However, good effect was produced by the introduction of MMT to the properties tensile strengthand hardness of the two kinds of nanocomposite, furthermore, better effect was produced in the SMMT/PS nanocomposite.With the comparison of the impact strength and the tensile strength of SMMT/PS prepared by emulsion polymerization and melt intercalation respectively, the results indicated that the properties of the SMMT/PS by emulsion polymerization were better than that by melt intercalation, which proved that the SMMT could not play the advantage in melt intercalation that it can joint with polymers by chemical bonds, but joint with polymers in weak acting force like OMMT.