改性纳米碳酸钙-聚丙烯复合材料的结构与性能研究

STRUCTURE AND PROPERTIES OF iPP/MODIFIED NANO-CaCO_3 COMPOSITES

制备了硬脂酸钙包覆的纳米碳酸钙(CaSt-nano-CaCO3),并采用熔融共混的方法制备出iPP/CaSt-nano-CaCO3和iPP/nano-CaCO3复合材料.与纯iPP相比,复合材料的弯曲强度和弯曲模量随着CaCO3粒子含量的增加而提高,冲击性能也得到改善.相对于iPP/nano-CaCO3,iPP/CaSt-nano-CaCO3复合材料的冲击强度略有改善,而弯曲强度和弯曲模量明显提高.偏光显微镜和示差扫描量热研究表明,随着CaSt-nano-CaCO3含量增大,复合材料的结晶温度升高,成核性能增大,但其结晶温度低于同等粒子含量的iPP/nano-CaCO3复合材料,即CaSt-nano-CaCO3对iPP结晶的成核作用弱于nano-CaCO3,表明CaSt的引入降低了CaCO3的成核活性.广角X射线衍射试验研究表明引入改性与未改性纳米碳酸钙后复合材料均未出现β晶型.熔体流动速率测试表明,相比于iPP/nano-CaCO3,硬脂酸钙的存在改善了复合材料的加工流动性能.

Calcium stearate modified nano-CaCO3（CaSt-nano-CaCO3） was prepared,and iPP /calcium stearate modified nano-CaCO3（iPP/CaSt-nano-CaCO3） was prepared by melt blending iPP with CaSt-nano-CaCO3 particles.Compared with pure iPP,the addition of CaSt-nano-CaCO3and nano-CaCO3particles both increased flexural strength and flexural modulus of iPP,and impact strength was also improved in these two series composites.In comparison with iPP/nano-CaCO3,the impact toughness of iPP/CaSt-nano-CaCO3composites was improved slightly,while the flexural modulus of iPP/CaSt-nano-CaCO3was obviously increased.Differential scanning calorimetry（DSC） and polarized optical microscopy（POM） tests showed that with increasing CaSt-nano-CaCO3content,the crystallization temperature and the nucleating ability of the composites were all increased.The crystallization temperature of iPP/CaSt-nano-CaCO3is lower than that of iPP/nano-CaCO3 with the same filler content,indicating that the nucleating ability of CaSt-nano-CaCO3is weaker than that of nano-CaCO3 in iPP matrix.Wide-angle X-ray diffraction（WAXD） results showed the composites did not exhibit β crystal form after addition of nano-CaCO3and CaSt-nano-CaCO3 particles.Compared with iPP/nano-CaCO3,the presence of calcium stearate increases the melt flow rate（MFR） of iPP composite with the same filler content,implying that the processability of the composites will be improved with the modification of nano-CaCO3 with calcium stearate.