The Preparation And Flame Retardant Modification Of The Polylactic Acid/Nano-size Core-shell Silicone Rubber Spheres Composites

In this dissertation, the nano-size core-shell structure polymethylsiloxane poly(methy methacrylate) (CSP1)spheres and polymethylsiloxane-poly(butyl methacrylate) (CSP2)spheres were prepared. Using two nano-size core-shell structure spheres and B2O3 and melamine polyphosphate (MPP), the polylactic acid was modified. Mainly work as follows:Using the seed emulsion polymerization method, two nano-size core-shell structure silicone rubber spheres were prepared. The synthesis mechanism conversion rate, structure, the thermal stability, XRD and contact angle of two spheres were studied. Experimental results showed that:the about 100nm core-shell structure silicone spheres could be obtained by seed emulsion polymerization, and the conversion rate can reached about 98%.Using these two spheres, the polylactic acid was modified. The PLA-CSP1 and PLA-CSP2 composites were obtained. The toughness, thermal stability, decomposition activation energy and the crystallization behavior of these two composites were tested. The results showed that the shell of the nano-size core-shell can raise the compatibility between polylactic acid and silicone rubber. The silicone rubber spheres can enhance the thermal stability of composites in high temperature, the decomposition activation energy and the crystallinity of the composites.Since the B and Si elements can raise the stability of the carbon residue, the flame retardant PLA-CSP2-MPP-B2O3 composites was obtained by using CSP2, B2O3 and MPP. The toughness, thermal stability and combustion performance of the prepared composites were tested. The results showed that the tensile strength and toughness could be increased by CSP2, the tensile strength could be increased by B2O3. The oxygen index and the combustion levels could be increased by MPP and B2O3. But on the other hand, the thermal stability of materials were decreased.