Preparation Of Nano-Kaolin And Application In PVC Composite

Polyvinyl-chloride is one of the earliest industrialization plastic varieties, but it is brittle. Therefore, it is necessary to carry on the studies of reinforcing and toughening modification to obtain PVC composite with high performances. As a kind of inorganic filler, Kaolin is applied to polymer modification widespread because of rich resource, cheap price and other advantages.Nano-Kaolin was prepared by intercalation layer-swelling-explosion method. Firstly inserting the potassium acetate small molecular to the Kaolin interlayer, which enlarged Kaolin layer-space by swelling, Secondly, pyrolyzing potassium acetate into CO2 and steam under 400℃, nano-Kaolin could be obtained by this gas explosion force. The effect of potassium acetate content, intercalation time, water content on intercalation ratio were discussed and the best conditions were optimized: When weight ratio of potassium acetate with Kaolin was 1, intercalation time was 24 hours, the water content was 10%, intercalation ratio was the best, reaching as high as 90%. The micro-structure, particle size distribution and morphology characteristic of Kaolin-potassium acetate intercalation compound and nano-Kaolin were characterized by X-ray Diffraction, Fourier Transform Infrared Spectra, Particle Size Analysis, Scanning Electron Microscope.Kaolin was treated by coupling agents. It was indicated by apparent phenomenon observation, extraction experiment, FTIR and oil adsorption value's change that coupling agent and Kaolin surface occurred chemical invigorate connection, coupling agent not only changed the Kaolin surface performance, but also changed Kaolin's particle inter-space among internal and inter.Mixing modified Kaolin with PVC and other additives according to formula uniformly, the blending and filling of PVC and Kaolin was realized on opened refine rubber machine. PVC/Kaolin composites were prepared and their mechanical properties were tested. The influence of Kaolin content, coupling agent content and type, the stabilizer content and the plasticizer content on mechanical properties were discussed and the best formula was optimized : When Kaolin content was 8%,coupling agent was 2.0%,the stabilizer was 2.0%,the plasticizer was 10%, mechanical performance of the composites was the best. The material tensile strength reached 54MPa, elongation at break reached 120%,unnotched impact strength reached 43kJ/m2. It was indicated that thermal stability of the compound was obviously superior to the pure PVC material by TG analysis: material initial weightlessness temperature improved from 120℃to 150℃. The break form of the material's cross section happened qualitative transformation by SEM: from brittle fracture transformed into ductile fracture. Modified Kaolin had played dual function of reinforcing and toughening, the anticipant results were achieved.