| Poly(vinyl chloride) (PVC) resin is a widely used thermoplastic because of its particular properties, easy modification, fire retardance and low production cost. But PVC is unstable when exposed to high temperature during its moulding and application, and produces a lot of smoke during its burning, which restrict its application in some field. The aim of this paper is to prepare PVC/hydrotalcite (HT) nanocomposites with good thermal stability and low smoke density. Considering the strong electrostatic force between layers of HT and the difficulty of exfoliation HT, intercalation of HT with unsaturated organic acid groups and of VC in-situ suspension polymerization in the presence of intercalated HT were carried out to prepare PVC/HT nanocomposite resin in the thesis. The resins were processed and the structure and properties of the PVC/HT nanocomposites were investigated.Firstly, taking advantage of the exchange ability of the interlayer anion of HT, the unsaturated organic acid groups A or unsaturated organic acid groups B intercalated HT (Mg:Al = 2:1) has been successfully assembled by co-precipitation and swelling rehydration method. The crystal structure and chemical structure of intercalated HT was analyzed. The results showed that undecenoate and olelate groups entered the interlayer of HT availably. Basal spacing of HT increased from 0.78 (with anoin of NO3-) to 2-3nm. FT-IR and TG results showed that there were electostatic ction and hydrogen bond between the host and guest. A supermolecular structure model of pillared HT was proposed based on the above results.Then, the rules and mechanism of VC suspension polymerization in the presence of HT particles intercalated with undecenoate and olelate group, were investigated. Compared to pure VC suspension polymerization system, the pressure of reaction system started to decrease early, and the conversion decreased at the same pressure drop. Adding of HT had no significant effect on the particle size and particle size distribution of PVC composite resin. A part of PVC was intercalted into HT through the copolymerization of VC and intercalated unstatured anoin groups, and HT was partially exfoliated. TGA results showed that the thermal stability of PVC/HT resins was enhanced prominently. The temperature ofPVC/HT resins (HT 5.0 wt %) at 5% weight loss increased about 20℃.PVC/HT nanocomposites were obtained through processing of PVC/HT composite resins. From TEM micrographs of PVC/HT nanocomposites, it was shown that the size of most HT particles was smaller than 100 nm in the nanocomposites. HT particles were mostly exfoliated, dispersed homogeneously and in orientation in PVC matrix with nanoscale. The study of the properties of PVC/HT nanocomposites showed that HT could enhance the dynamic thermal stability of PVC/HT nanocomposites. The dynamic thermal stability time of the composites (HT5.0wt%) prolonged 30min. HT only reduced the speed of the degradation reaction of PVC, but didn't change the mechanism of degradation. The flame-retardance of PVC/HT nanocomposites was enhanced. The maximum smoke density of PVC/HT nanocomposites (HT1.25wt%) decreased about 40%. The tensile strength and Charpy impact strength of PVC/HT nanocomposites were greater than that of pure PVC when the incorporated amount of HT was less than 5wt%.
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