Studies On Preparation And Properties Of PVC/Clay Nanocomposites

Polymer/clay nanocomposites is a new class of material. They can attain excellent mechanical properties, thermal stability and barrier properties at lower clay content. Their potential applications include film, food packing, components in electrical parts, automobile and airplane.In this thesis, by melt, emulsion and solution mixing, PVC/clay nanocomposites were first prepared and studied. The morphology, mechanical properties and thermal stability of the hybrids were systemically considered and compared. A relatively convenient method of preparation was found.In order to avoid more complicated element analysis and the measure of cation exchange content, a simple method of measuring swelling value of clays was employed to distinguish Nat-clay and Ca2~-clay. Na~-clay was modified with hexadecyltrimethylammonium bromide. The organic clay obtained was then characterized by FTIR,TGA and XRD.The morphology of PVC/clay composites prepared by means of melt mixing was characterized by XRD, TEM. The results indicated that the nanometer organic clay was uniformly dispersed in the PVC matrix. Although PVC/inorganic clay composite was conventional microcomposite, the size of clay was greatly decreased. It shows that the mechanical properties, Vicat softening point (VSP) and dynamic mechanical properties of PVC/organic clay composites were improved. The migration of plastisizer in the composite was decreased.PVC/inorganic clay hybrids were prepared by means of emulsion mixing. The TEM analysis exhibited that clay was dispersed in nanometer in PVC matrix. Theimpact strength of composites increased with the clay content. The thermal stability of composite was enhanced, and the migration of plastisizer was decreased.The PVC/inorganic clay composite, prepared by a new method of suspension polymerization of Vinyl chloride in the presence of clay, was first tentatively studied.IIIThe result of TEM analysis indicated that the size of clay in PVC matrix was decreased. The thermal decomposed temperature and VSP increased with the clay content.PVC/organic clay nanocomposite was prepared by means of solution intercalation. The clay in the composite was exfoliated. The impact strength, elongation at break and storage modulus promoted while the strain intensity had no obvious decrease.By comparing the morphology, mechanical properties and thermal stability of the composites through different methods, it was found that the morphology and properties of the composites by means of melt mixing were similar to those by solution mixing. But the method of melt mixing has wider application. At the same clay content, the properties of PVC/organic clay composite were superior to those of PVC/inorganic one. The clay was dispersed homogeneously in the composite prepared by emulsion mixing and the mechanical property and thermal stability of it got the relatively highest improvement.