| Polymer-layered silicate nanocomposites, is a new type polymeric material with excellent performance and wide applications, and have attracted much attention in the academic and industrial aspects in recent years. The aim of this study on PET/MMT intercalated nanocomposite is to further improve PET properties, and to exploit novel applications for PET.In this thesis, firstly, the PET/MMT nanocomposites were prepared by polymer melt intercalated method. PET and organically modified MMT were mixed in twin-screw extruder. The non-isothermal crystallization kinetics of PET/MMT nanocomposites was systemically studied. The toughening and their rheological behaviors of PET/MMT intercalated nanocomposites were also studied. A reinforced composite with super toughness, high strength and thermal stability was obtained. The key project, super toughenned PET composite, from Shanghai Science and Technology Committee was successfully completed (2002,9-2004,8).Organic montmorillonite was prepared by ion-exchange reaction. The influences of different alkylamine modifiers on the ion-exchange reaction were studied. The results indicated that the modifiers withlonger molecular chain, higher flexibility or bigger steric hindrance possess better intercalation effect. As a result, it was easier for intercalative polymerization between montmorillonite interlayers.PET/MMT intercalated nanocomposites were prepared by polymer melt intercalation method. XRD and TEM results showed that PET molecules could intercalate into organic montmorillonite interlayers. The crystallization temperature Tmc and the decomposition temperature Td of intercalated nanocomposites could be significantly increased. The thermo deformation temperature and tensile strength of nanocomposites with uniformly dispersed MMT were also greatly improved.The non-isothermal crystallization behavior of PET/MMT intercalated nanocomposites, in comparison to pure PET, were investigated by DSC. The results indicated that the crystallization temperatures of the nanocomposites were much higher than that of pure PET. The crystallization nucleation rate was improved, and Avrami index n and rate constant Zc was markedly increased due to the nucleating effect of MMT.The rheological behavior of composites of PET /MMT /elastomer were investigated by capillary rheometer. The results showed that all samples exhibited shear-thinning behavior. Non- Newtonian flow behavior of the PET/elastomer blends are more distinct and their apparent viscosity increased with the increase of elastomer content, while the introduction of MMT greatly decreased the viscosity of the blends. In addition, the viscous flow activation energy of PET/elastormer was decreased with the increase of shear rate. And the apparent viscosity of PET/ MMT /elastomer was more temperature dependent while that of PET/elastormer was less.The toughening of PET/MMT intercalated nanocomposites was achieved by blending with elastomer as toughener. The structure andmorphology were characterized by XRD, TEM, AFM and SEM. The results showed that notched impact strength of composites was greatly improved with the adding of elastormer. SEM micrographs of impact fracture surfaces of nanocomposites showed that the compatibility of PET and elastormer could be improved with the adding of compatibilizer. As a result, the notched impact strength was further increased. Various influencing factors on the impact toughness of blend system were valued and the toughening mechanism of elastormer was proposed. Moreover, the blend systems reinforced by glass fiber was primarily studied. And a composite with high notched impact strength, tensile strength and thermal stability was obtained. |
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