CaCO_3表面包覆改性及其对填充PP力学性能的影响

先用丙烯酸(AA)处理CaCO3,在其表面引入活性双键基团后,再通过固相包覆反应将聚丙烯蜡(PPW)固定在CaCO3表面.实验发现改性CaCO3可经受甲苯、稀盐酸处理而不发生溶解,结合红外及热重分析结果,证明PPW已经通过化学键合而成功地包覆在CaCO3表面.将该改性CaCO3填充聚丙烯(PP)后,发现PP的冲击性能及拉伸性能均有不同程度的提高,当改性CaCO3的填充量为15份时,体系的缺口冲击强度达到最大值,为基体树脂的1.68倍;当改性CaCO3的填充量10份时拉伸强度达到峰值,为同等添加量的未改性CaCO3的1.22倍.

CALCIUM CARBONATE SURFACE COATING MODIFICATION AND IT'S EFFECT ON THE MECHANICAL PROPERTIES OF FILLED POLYPROPYLENE

Recently,polypropylene toughened and strengthened by ultrafine calcium carbonate(CaCO_3) has become more and more popular.But for its high surface energy,the compatibility between CaCO_3 and polypropylene is poor,so the surface of CaCO_3 must be modified before use.In this article,CaCO_3 whose surface was pretreated first by acrylic acid(AA) to introduce active double bond groups,was coated chemically by polypropylene wax(PPW) via solid-phase coating polymerization.Compared to traditional solid-phase grafting polymerization,this method has some differences.First,the reaction is not between monomers of small molecular weight and polymer,but between CaCO_3 pretreated by AA and PPW;Second,the polymer is usually a solid phase mass under the reaction temperature in the traditional solid-phase grafting polymerization,but in this method PPW is in the liquid phase,and the CaCO_3 pretreated by AA in the solid phase.Third,in traditional method the reaction is the monomers grafting to the polymer's surface,but in this method the coating reaction is PPW to the AA on the CaCO_3's surface.As this method can occur in high-speed mixer,it is more convenient and feasible comparing to the traditional grafting reaction which is usually in extruder or reactor.In this article,it is found that coated CaCO_3 can stand the treatment of both methyl benzene and dilute hydrochloric acid.Combined the results of FTIR and TGA,the conclusion can be made that PPW has been coated successfully with polyacrylic acid on the surface of CaCO_3.After filling the coated CaCO_3 into polypropylene(PP),it shows that the impact and tensile properties of PP are improved in somewhat degree.When the content of the coated CaCO_3 is 15 phr,the notched impact strength of the PP composite is 1.68 times as high as that of PP.When the content is 10 phr,the tensile strength of PP filled with coated CaCO_3 is 1.22 times higher than that of PP filled with uncoated CaCO_3 at same contents.