Study On Structure And Performance Of Polypropylene/wollastonite Composites

Wollastonite,a kind of metasilicate mineral of calcium, has been widely applied asreinforcing filler for polymeric compound materials for its non-toxicity、chemical resistance、thermal stability、excellent dimensional stability、mechanical property、electrical property andgood reinforcing performance. As the most widely used general plastics,polypropylene hasoutstanding comprehensive performance.However, their poor toughness of polypropylene andthe different surface energy polypropylene brings difficult compatibility with inorganic filler.Thus, wollastonite needs surface activation and organification to increase its dispersibilitywith polymer.The authors coated wollastonite with PBMA solubility parameterin was almost the sameas PP’s in soap-free emulsion polymerization process.The new organic chains of wollastonitewere characterized by FTIR、TG, the surface property of wollastonite was characterizedSedimentation volume、surface contact angle and the dispersion morphology of wollastonitefilled PP matrix was observed by SEM and the crystallinity was observed by POM.What hasbeen mainly researched was the influence of the content of BMA and the best condition ofpretreatment on the surface characteristic of wollastonite under the best pretreatmentcondition, as well as the influence on the structure and performance of PP/wollastonitecompound system.The results show that in-situ Soap Free Emulsion Polymerization was carried outbetween functionalized particles and BMA monomer to modify the surface of Wollastonite,the surface of wollastonite-coated turned from originally hydrophilic to hydrophobic andwollastonite-coated is fully dispersed in PP matrix and the interfacial compatibility isremarkably strengthened due to the surface coating. The POM test revealed that wollastonitehad obvious nucleation on the crystallization of PP.When the content of coated wollastonitewas10%, the mechanical property of compound material was optimized, and the processingfluidity decreased with the increment of the surface coated wollastonite. PP/wollastonitecompounds was shear thinning fluid and its non_Newtonian index was below1, so the melt was pseudoplastic fluid. The apparent viscosity reduced while the temperature increased, andat the same temperature and shear rate, the apparent viscosity of PP/PBMA coatedwollastonite compounds increased successively.