Preparation, Structure And Properties Of Poly (Ethylene Terephthalate)/Montmorillonite Nanocomposite

Preparation of polymer/montmorillonite nanoconposites considered to be kinds of important method of polymer modification. Na-montmorillonite(Na-MMT) was modified with organic reagents that have reactive end-groups with them and organo-montmorillonite was obtained. Poly(ethylene terephthalate)(PET)/montmorillonite nanocomposite was prepared by two methods of intercalated polymerization and melt intercalation. Structure and properties of different intercalation hybrids were systemically studied. The following important research and develops were achieved:A series of new organic agents (SS) , which have reactive end-groups with them and especially suit to PET, were prepared and used for organic treatment of Na-MMT . Different structure and properties of PET/montmorillonite nanocomposites were obtained by intercalated polymerization and melt intercalation. The results indicate that there are the very good compatibility between montmorillonite and PET. Also corresponding method and technology was applied for a China Patent.The process of preparation of organo-montmorillonite was studied. The number of branch chains that link to SS organic reagents chain has different influences to the ability of absorption and expanding the interlayer distances of montmorillonites. The SS organic reagent with one branch chain has the best ability of ion exchange reaction and that with two branch chains has the best ability of expanding the interlayer distances of montmorillonite.It was first reported on study of in-situ polymerization process of PET/ montmorillonite nanocomposites. The effect of quality of original montmorillonite, morphology and content of organo-montmorillonite on in-situ polymerization process was studied. The best process conditions for in-situ polymerization and reaction kinetics parameters are given. The addition of organo-montmorillonite increased the esterification rate and the polycondensation rate of PET polymerization, but also decreased the mass transfer rate of polycondensation due to barrier property of montmorillonite flakes to small molecules of reaction system. It was shown thatorgano-montmorillonite can catalyze both esterification and the polycondensation reactions.Characterization of PET/montmorillonite nanocomposites prepared by both intercalated polymerization and melt intercalation were studied. The intercalate, exfoliate and dispersing status actions of montmorillonite in PET phase were investigated by XRD, TEM and SEM. The effect of montmorillonite flakes on structure of PET molecule chains was studied by XRD and ER. In in-situ polymerization prepared nanocomposites PET molecule chains mostly take right-and left conformations, while in melt intercalation prepared nanocomposites they take trans conformations, and similar to the pure PET they mostly take trans conformations. Organo-MMT in the nanocomposite was exfoliated and dispersed better by in-situ polymerization process than by melt intercalative. The "retrogression" phenomenon, which concerned with the action of shrinking the interlayer distance of MMT was newly explained as the result of decomposition or desorption of organic agents from MMT layers.The thermal property and isothermal crystallization kinetics of nanocomposites were investigated by DSC and TGA. It was shown that montmorillonite did not act as a nucleating agent abviously in PET crystallization processes for the in-situ polymerization prepared nanocomposite, but more behaved as a plasticizing agent. The crystallization rate of nanocomposite was increased. While the crystallization temperature lowered. Hence, the ability of melt crystallization decreased. Montmorillonite acted as a very good nucleating agent in PET crystallization processes of melt intercalation nanocomposite. The presences of organo-montmorillonite complicated the crystallization processes of PET. The org-modified agent took part in polycondensation of PET in polymerization process. The author suggested a "patter plate effect" theory, which considered that the special structure of O-MMT inter...