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Abstract
A novel modified nano-calcium carbonate (R-CCR) was prepared by coating a layer of organic compound with three functional groups (–OH, –COOH and C=C) on the surface of CCR (a commercial nano-CaCO3 modified with stearic acid) powders in solid state. Fourier transform infrared spectrometer (FTIR) indicated that the modifier is combined on the surface of CaCO3. Transmission electron microscope (TEM) showed the particle sizes of R-CCR and CCR locate in the range of 40 ∼ 90 nm. The mechanical property results show that R-CCR and EPDM have obvious synergistic toughening effects on PP. The determination of density and swelling ratio suggest that the cavitation of PP/EPDM/R-CCR composite is bigger than that of PP/EPDM/CCR. Scanning electronic microscopy (SEM) photographs of the impact-fractured surfaces show that there are many little cavities in the PP/EPDM/R-CCR system, R-CCR particles disperse in the matrix more uniformly and finely, and the agglomeration is weakened. The SEM photographs of the tensile-fractured surface of PP/EPDM/R-CCR show a fibroid morphology and large-scale yield deformation. The addition of R-CCR induces the formation of β–phase PP and the content of β–phase PP increases obviously after addition of EPDM. The synergistic toughening effects of R-CCR and EPDM on PP come from the dual effect of cavitation and β–phase PP. The 5% weight loss temperature of PP/EPDM/R-CCR composite is 70.5°C higher than pure PP. The VICAT of the PP/EPDM/R-CCR composite is 8.4°C higher than the PP/EPDM composite.
