Study On Nano SiO₂ Modified PP/Micro-crystal Muscovite Composites

Polypropylene(PP) is one of five general plastics, it has rich source and low price. Compared with other common plastics, general performance of polypropylene is better. But PP also has some shortcomings such as brittleness at low temperature, low mechanical strength, low rigidity, great molding shrinkage, etc. Thus restricts its application scope enormously. Therefore,in the PP modification research fields, making PP has high performance has become one of the richest prospect research directions.As a new kind of minerals found in west Sichuan area, the micro-crystal muscovite has excellent properties of muscovite group minerals, so it has wide exploitation and application prospect in application domains of many polymer materials.With "little size effect" and "surface effect", nano-SiO₂ has many special properties which different from other particles. Modification of PP by nano-SiO₂, excellent performance pp composities can be got.In this article,nano-SiO₂ was selected as thoughening agent,and micro-crystal muscovite as reinforcements and PE-g-MAH was selected as compatilizer blending technology was used in preparing PP composites which has appropriate properties. The properties of thoughening and strengthening of polypropylene with micro-crystal muscovite and nano-SiO₂ was systematically studied. And the mechanism of thoughening and strengthening of composites was probed elementarily. Through above researches,some conclusions could be taken as follow:(1)In order to enhance compatibility of PP with micro-crystal muscovite and nano-SiO₂, micro-crystal muscovite and nano-SiO₂ was modified. The modification effect of Silane coupling agents KH-550 on micro-crystal muscovite and nano-SiO₂ was studied by FT-IR and viscosity. The result indicated that the coupling molecules has grafted onto the surface of filling, and decreased the aggregation of micro-crystal muscovite and nano-SiO₂ particles effectively. (2)PP/micro-crystal muscovite in-suit composites were prepared by blending extrusion. The influences of micro-crystal muscovite content and extrusion temperature on the properties of the composites were investigated. The result showed that, with 15% micro-crystal muscovite, the composites obtain the maximum tensile strength,19.3%more than that of pure PP. with 10% micro-crystal muscovite, the composites obtain the maximum Izod impact strength,19.3%more than that of pure PP.(3)The orthogonal experiment with three factors at three levels was designed to test the effect of micro-crystal muscovite, nano-SiO₂ and PP-g-MAH amount on the performance of PP/micro-crystal muscovite/nano-SiO₂/PE-g-MAH blend. The optimum proportion is: PP/micro-crystal muscovite/nano-SiO₂/PE-g-MAH= 100/20/1/5. The izod impact strength was increased 41.3% and the tensile strength was increased 17.5% contrast with pure PP. Through above analysis,the properties of composite could be improved,such as thoughening,strengthening, which modified by nano-SiO₂ and PE-g-MAH.(4)The results showed that the izod impact strength and the tensile strength of the composites increased with increasing nano-SiO₂ content. The Izod impact strength was increased 37.8% and the tensile strength was increased 8.7% contrast with PP/micro-crystal muscovite,achieved the highest value when 1% nano-SiO₂ by weight modified with silicone coupling agent and PE-g-MAH was added.(5)The impact strength and the tensile strength increases with the increasing of PE-g-MAH. The best content of PE-g-MAH is 5percent.(6)The interface between the fillers and the matrix and the cause which improves their performance are explained through analyzing the surface morphology of the impact fracture by means of SEM, the results showed that micro-crystal muscovite and nano-SiO₂ was dispersed well in PP,which promoted the matrix undergo shear yielding rather than brittle fracture.