Studies On Preparation And Stabilities Of Polymer/Inorganic Nanocomposites

Polymer based inorganic/organic nanocomposites have extracted extensive research interests due to their unique properties.The nanocomposites combine the advantages of the inorganic materials(rigidity,high thermal stability and unique optical,electronic and magnetic properties)and the organic polymers(flexibility,dielectric,ductility and processability),which is different with the single material and conventional composite materials.Moreover,these polymer based inorganic/organic nanocomposites have potential applications in mechanical,thermal,electronic,and optical fields because the inorganic particles could be well dispersed in polymer matrix in nanometer scale.In this thesis,we aim at the preparation and stabilities of the polymer/inorganic nanocomposites.The research is focused in three aspects:1.The poly(vinyl chloride)/magnesium hydroxide(PVC/MH),poly(vinyl chloride)/calcium carbonate(PVC/CaCO₃)composites with different amounts of the inorganic particles with different sizes and morphologies were prepared by a solution method and their thermal stabilities were compared by TGA technique.The thermal stabilizing mechanism was developed via a facile chemical analysis method after the samples pyrolyzed.2.The photo-oxidation of the pure PVC and PVC/ZnO,PVC/CaCO₃ nanocomposites were prepared by a solution method with UV-irradiation at 365nm were compared with FT-IR,TGA,XPS and dissolving properties.It was found that the photo-active ZnO nanoparticles accelerated the photo-degradation of PVC and avored the crosslinking reaction of the dehydrochlorinated PVC.The photo-inert CaCO₃ nanoparticles hampered the photo-degradation of PVC.3.A new method for the preparation of core-shell halloysite nanotubes/polystyrene (HNTs/PS)nanoparticles was developed successfully.It involves the facile soap-less microemulsion polymerization.A possible mechanism for the formation of the monodispersed core-shell nanoparticles was also presented.At the same time,the unusually high percentage of grafting(PG%)of more than 230%was achieved in the halloysite nanotubes/polystyrene(HNTs/PS)nanocomposites with different amounts of the organo-HNTs added by the present bulk polymerization of styrene with organo-modified halloysite nanotubes(organo-HNTs)as macromonomers.It was explained with the crosslink reactions of the grafted polystyrene chains in the inner hollow space of the halloysite nanotubes and between the halloysite nanotubes each other. So the resulting nanocomposites HNTs/PS and HNTs-PS showed higher thermal stabilities than that of the pure polystyrene.