Preparation And Characterization Of Environment-Friendly PVA/OMMT Nanocomposites

The environmentally friendly poly(vinyl alcohol)(PVA)-based water-soluble biodegradable composites provides a wonderful way of resolving the problem of the"white pollution"which exists in all of the world. But what restricts the application of PVA is its solubility that will influnces the perfornance. PVA/OMMT(modified montmorillonite) nanocomposites is made to improve the water resistance, get better mechanical properties, enhancement the overall performance, and resolve the problem in use.Organo-montmorillonite(OMMT) is made from Na-montmorilllonite reacted with cetyl trimethylammonium bromide(CTAB). The interlamellar spacing is measured by XRD, by which the optimum parameters are obtained; IR spectra and TG curves show CTAB has intercalated into layers of MMT.To resolve the thermal aging problem in the course of extruding molding of PVA, calcium stearate is used in the preparation of PVA as a thermal stabilizer. The 0.5wt% addition is determined through mechanical properties test, surface state and TG test of PVA with different mass content of calcium stearate.To obtain proper OMMT additon to PVA/OMMT nanocomposites, mechanical properties test is done to the composites with OMMT mass contet of 1wt%, 3wt%, 5wt% and 7wt%, and 3wt% is chosen. Through XRD it can be seen that OMMT in PVA has totally exfoliated, thus exfoliation nanocomposites is prepared. Water resistance test and TG test indicate that the addition of OMMT improves the water resistance and thermal stabilization. Light transmitting test shows that in the short-wave area the light transmitting decreases less, while in the long-wave area it decreases more. Soil burial test shows that the OMMT prompts the degradation of composites, while it retards in the water degradation test.Nonisothermal crystallization of PVA and PVA/OMMT(3wt%) naonocomposites are studied by methods of DSC. The analysis result indicates that both the two composites has strong dependence on cooling rate, and that with the decreasing of cooling rate it apts to more intact crystals. It proves OMMT plays a role of heterogenerous nucleation in PVA/OMMT nonocomposites, and improves the rate of crystallization.