| The toughening of polyolefin has always been an important issue in applications of polymer. So far, the theories and technologies concerning polyolefin toughening with rubber or inorganic rigid particle have been studied comprehensively, which indicate that the toughening with rubber always lowers the modulus of materials, and toughening with inorganic rigid particle decreases tensile strength. However, the appearance of nano-inorganic particle has made it possible to increase the toughness, tensile strength and stiffness of polyolefin simultaneously. In this paper, nano-CaCOa synthesized in High Gravity Field is pre-treated and polyolefin/nano-CaCO3 is prepared by melt-blending. The influence of the content of nano-CaCO3 particle, varieties of surface treating agent and matrix toughness on the structure and the mechanical properties of the composites is investigated detailedly, laying a substantial foundation for its high performance.The process that nano-CaCO3 synthesized in High Gravity Field is modified with fatty acid salt A and coulping agent B1(B2) is studied and the optimal technology factors are determined. For A, the optimal conditions is as follows: time is about 30~40min, temperature is about 40-50 # and modifying agent dosage is about 3%~5%. For B, time is 30~40min and modifying agent dosage is 3%~5%. Modification efficacy is evaluated using classical liquid contact angel measurements, meanwhile, the surface characterization of modified nano-CaCO3 is investigated by means of FTIR. Finally, the process of absorption is expounded effectively by two stage model and the coupling mechanism is dicussed by dispersion stability model.The method that nano-CaCO powder is treated with coupling agent C by supersonic is investigated, the optimal technology factors [time (30~40min) and modifying agent dosage (3%~5%)] are obtained.The dependencies of the structure and the mechanical properties of PP/nano-CaCOs blends on the concentration of nano-CaCO3 particle, varieties of surface treating agent and matrix toughness are investigated. The results show that the varieties of treating agent has obvious influence on the dispersion of nano-CaCO3 in substrate. The mean size of CaCO3 treated with fatty acid salt A is 149nm when its content is 2% and 157nm when its content is 6%, while the average size of CaCO3 treated with coupling agent B2 is 143nm when its content is 2%. So it is concluded that the mean size can be less than l00nm by improving treatment effect or treatingnano-CaCOa particle synthesized fresh. Moreover, it is found that PP is toughened dramatically by nano-CaCOa when the content is about 5~6%. The impace strength of PP/nano-CaCOa composite increases by 50% and PPR by 1 times with the addition of nano-CaCOs treated with fatty acid salt A, while tensile strength and stiffness of PP and PPR are remained basically; the complex properties of composite containing nano-CaCOa treated with coupling agent 61(62) are remarkably better than those of composite filled with nano-CaCOs treated with fatty acid salt A; the toughening behavior of nano inorganic particle is different from that of elastomer, matrix needs comparatively good impact strength, for example, PPR can be toughened more effectively than PP. SEM shows that the fracture surface of sample of neat PP is smooth and has very little plastic deformation, in contrast, fracture surface of sample of composite is rough and has extensive plastic deformation.The influence of the content of nano-CaCOs, varieties of surface treating agent on the structure and properties of HDPE/nano-CaCOs composite is analyzed. The results demonstrate that the varieties of treating agent has obvious influence on the dispersion of nano-CaCOs in substrate and the complex properties of composite. For nano-CaCOs treated with fatty acid salt A, it disperses poorly in the matrix, simultaneously, the impact strength of HDPE/nano-CaCOs composite decreases but higher than that of the composites blended with product from Shanghai and Mengxi. For nano-CaCOs treated with coupling agent...
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