| The polyvinyl acetate(PVAc) is a low toxic adhesive. It is one of the most important commercial thermoplastic materials and widely used in many fields due to its high bonding strength, easy processability, convenient to use, cost-effectiveness, safe and nontoxic. With the development of technology, higher performance requirements for polyvinyl acetate materials are put forward. However, traditional PVAc also has its shortcomings, such as poor water resistance, low heat resistance, and significantly reduces its adhesion under hygrothermal conditions. Therefore, its applications have been restricted. Bentonite is a kind of layered silicate, which exhibits excellent heat-resistance, good mechanical properties and high barrier performances. And silane coupling agents have the ability to form a durable bond between organic and inorganic material, they can improve the performance of materials by combine organic phase-silane coupling agent-inorganic phase. In this thesis, we utilize the structural characteristics and performance advantages of bentonite and silane coupling agents to enhance the qualities of PVAc such as water resistance, heat resistance and mechanical property.In this paper, we used the organobentonite(OMMT) modified by acrylic acid and silane coupling agent KH570 to prepare PVAc/OMMT/KH570 composite emulsion by emulsion polymerization. We explored the morphology of the composite by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR) and transmission electron microscopy(TEM). And we also studied the stabilities, water resistance, heat resistance and mechanical properties of the composites. The results showed that with the addition of KH570, the OMMT dispersed more evenly and most of them were exfoliated in the system; the initial weight-loss temperature of films was enhanced to 298.5oC from 241.0oC, the tensile strength was increased from 7.6±0.3MPa to 11.4±0.3MPa, and the water resistance was also improved remarkably.The influence of different dosage of OMMT and KH570 on the performance of composite emulsions was investigated. By comparison, we’ve found that the comprehensive performance of the emulsion is better when the dosage of OMMT and KH570 was 3 wt%(relative to the monomer).We synthesized KH570 oligomer(PKH570) by hydrolysis method and prepared PVAc/OMMT/PKH570 composite emulsion. It turned out that with the modification of KH570 oligomer, the performance of composite emulsion was improved significantly. The initial weight-loss temperature of films was increased from 241.0 oC to 258.9oC,and the maximum decomposition temperature was also enhanced to 351.3oC from 336.4oC. The water-solution content and water absorption of the films decreased appreciably. The tensile strength was increased from 7.6±0.3MPa to 24.5±0.3MPa, but the toughness became lower than before。Furthermore, we successfully completed the PVAc/OMMT composite emulsion pilot scale test and got stable products. It provided an important reference for the industrialization of the preparation technology. The products were used in coatings and polymer mortar. The coating we got with PVAc/OMMT composite emulsion was conformed to the use standard. We prepared the polymer mortar with the composite emulsion and investigated the effect of emulsion content on compressive property, flexural property and adhesive strength of polymer mortar. The results showed that the flexural strength was increased from 7.5MPa to 11.8MPa and adhesive strength was enhanced to 8.5MPa from 4.8MPa, but the compressive strength was decreased. In addition, polymer mortar had better comprehensive performance when polymer emulsion dosage was 10%. |
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