Polypropylene Composite Toughened by a Novel Modified Nano-CaCO3

摘要

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 Ra-CCR induces the formation of beta-phase PP and the content of beta-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 P-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.