| Polypropylene (pp) is a kind of universal thermoplastics with good performance. But PP also has some shortcomings such as brittleness at low temperature, low mechanical strength, low rigidity, great molding shrinkage, easily aging, poor heat resistance 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. In this thesis, to modify PP, thermotropic liquid crystalline polymer (TLCP) and nano-CaCO3 were used. So a new way of PP industrialization was developed.Using PP-g-MAH as a compatilizer, PP/TLCP in-suit composites were prepared by blending extrusion. The influences of TLCP content and extrusion temperature on the properties of the composites were investigated. The result showed that, with 5% TLCP, the composites obtain the minimum viscosity. Compared with PP, TLCP causing the PP heterogeneous nucleation crystallening, therefore, the crystallinity of the composites increased 1.03%. Also the tensile strength of the composites rose up to 38.22MPa, 18.4% more than that of pure PP. The elongation at break of the composites has the drop slightly, was 18.26%. FSEM observation showed that TLCP were fibered on the surface, but axiolitic or short fibered internally, and the interface of the two phases has a weak connection.In order to enhance compatibility of nano-CaCO3 with PP and TLCP, nano-CaCO3 was modified.The modification effect of Silane coupling agents A-174 on nano-CaCO3 was studied by FT-IR and SEM. The result indicated that the coupling molecules has grafted onto the surface of filling, and decreased the aggregation of nano-CaCO3 particles effectively. Under the condition that 90℃, 600 rap/min, stirring electrically for 30 minutes, the modification technological parameter is: A-174 content is 2%; alcohol-water proportion of A-174 solution is 1/2; the pH value of the solution is 4.0～5.0. The best modification effect was achieved: the activation degree and the oil absorption value of the modified nano-CaCO3 are 84.56% and 58.97 ml/100g. In order to study the processing method, the adding raw material method and enriching place of nano-CaCO3, PP/TLCP/CaCO3 in-suit hybrid materials were prepared respectively in a twin-screw extruder by one-step or two-step method, The toughing effect of nano-CaCO3 on PP/TLCP was then explored through POM, SEM, DSC and ulti-purpose mechanics testing machine. The result showed that, under the condition of the same proportion of PP/TLCP/ CaCO3/PP-g-MAH=85/5/4/6, the mechanical properties of molding sample by one-step method is better than those of molding sample prepared by two-step method, the tensile strength is 36.62 MPa, increase 2.95% which comparing to those of the sample prepared by two-step;the elongation at break is 35.12%, increases 76.4%;the impact strength is 38.6 kJ/m2,increases 4.9%.The element calcium is enriched in the PP matrix of /TLCP/CaCO3 sample prepared by one-step method, which is benefit to accelerate heterogeneous nucleation of PP, to make the crystal particles smaller, to speed the crystalliation rate, and to promote TLCP fibered in the PP base. Considering the structure, crystallin properties, mechanical properties of the composites in this studying field, preparing PP/TLCP/CaCO3 in-situ hybrid materials by one-step method with a small amount of TLCP (5%) and modified nano-CaCO3 (4%) is a new effective way to reinforce PP plastics. Adding TLCP not only increases the crystallinity and crystalliation rate of PP, but also improves the processing performance of PP and save energy, adding modified nano-CaCO3 can decrease the cost of composites, thus increase economical benefit, and expand the application of PP.
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