Study On Preparation Of PP-Nano Composites By ISBS Method And Its Mechanical Properties

Polypropylene has good overall performances, lower cost, the very broad scope of its application. But Polypropylene is brittle(especially at low temperature), thus modification of Polypropylene become inevitable trend.In the first of this paper, the preparation of nano St-MMA copolymer by emulsion polymerization were studied, then add the nano copolymer to the matrix Polypropylene by In Situ Bubble Stretch Method, so PP nanocomposites were prepared. The micro-structure of PP nanocomposites were tested by scanning electron microscope (SEM) , and the results showed that by the ISBS method, nano particles were dispersed within a certain distance to bubble; the structure of PP nanocomposites were tested by X-ray diffraction, and the results showed that as a result of adding nanoparticles to the matrix, theβ-PP was generated in the matrix PP. Meanwhile, the samples that were prepared were injected into variety of mechanical spline, and were tested in mechanical properties. The results showed that when the loading of nano particles was 2 percent, the mechanical properties of PP nanocomposites were optimum, compared with pure PP, the notched impact strength increased 103 percent, and the tensile strength increased 22 percent, and flexural strength increased 9.6 percent.In order to compare the effect in modification to PP by nano St-MMA copolymer with the effect in modification to PP by nano Styrene Butadiene Rudder(SBR), PP/nano SBR composites materials were also prepared by ISBS method. The micro-structure of materials were tested by scanning electron microscope, and the results showed that with the tension of bubble, the nano particles around bubble have been achieved nano dispersed, and we found that the size of nano particles were different from each other as a result of distance to bubble; If adding different capacity nano SBR to PP, the size of the nano particles by dispersed is different. The structure of PP nanocomposites were tested by X-ray diffraction, and the results showedthat as a result of adding nano SBR to the matrix, theβ-PP was generated in the matrix PP, so that the mechanical properties of composites materials had improved. The mechanical properties of test results showed that when the loading of nano particles was 7 percent, compared with pure PP, the notched impact strength increased 78.6 percent, and when the loading of nano particles was 3 percent, the tensile strength increased 29.8 percent, and flexural strength increased 14 percent, and the elongation at break increased 67 percent.