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ABSTRACT:The surface modification of nano calcium carbonate (nCaCO 3 ) particles was carried out with a soluble compound of lanthanum via a coating process of chemical deposition, and nCaCO 3 particles covered with a compound of lanthanum (nCaCO 3 -La) were prepared. The polypropylene (PP)/nCaCO 3 and PP/nCaCO 3 -La composites were prepared with a two-roll mill. The measurements of the mechanical properties showed that the impact strength of the composites increased at first and then decreased with the addition of fillers, and the tensile strength was reduced at the same time. The impact strength of PP/nCaCO 3 -La was higher than that of PP/nCaCO 3 , and the impact strength of PP/nCaCO 3 -5La was three times that of virgin PP. Transmission electron microscopy and scanning electron microscopy showed that nCaCO 3 -La dispersed well in the PP matrix, the size distribution of the particles was uniform, and nCaCO 3 -La adhered to the PP matrix very closely. The crystallization properties of virgin PP and its composites were studied with differential scanning calorimetry and wide-angle X-ray diffraction. The results showed that the ␤-PP phase easily formed with the addition of the lanthanum compound. In comparison with virgin PP, the addition of nCaCO 3 -La led to a higher crystallization temperature. The size of the crystallites increased with the addition of nCaCO 3 -La, and the nucleation of PP crystalline was also improved.

High rubber styrene-EPDM-acrylonitrile (AES) was prepared by the graft copolymerization of styrene (St) and acrylonitrile (AN) onto ethylene-propylene-diene terpolymer (EPDM) in n-heptane/toluene cosolvent using benzoyl peroxide as an initiator. The effects of reaction conditions, such as reaction temperature, initiator concentration, EPDM content, the solvent component, and reaction time, on the graft copolymerization are discussed. In addition, according to the research on mechanical properties of the SAN/AES blend, a remarkable toughening effect of AES on SAN resin was found. By means of scanning electron microscopy, the toughening mechanism is proposed to be crazing initiation from rubber particles and shear deformation of SAN matrix. Uniform dispersion of rubber particles, as shown by transmission electron microscopy, is attributed to the good compatibility of SAN and AES.

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