| Polypropylene(PP)has the advantages of high melting point and tensile modulus,excellent heat and ultraviolet resistance.It can save cost and weight compared with metal materials,and is fully recyclable.However,its resistance to surface damage caused by machinery is poor,which will reduce the subjective perception of product quality and increase the local stress of the product and reduce its mechanical strength,which has become an increasingly important issue,limiting its wider application to the automotive industry.In this paper,polypropylene SP179 was adopted as the substrate,and surface modified wollastonite was added into the matrix by means of melt blending,and the nucleating agent with excellent nucleating effect,the scratch resistant agent with high efficiency to improve the scratch resistance were also used in the matrix.PP composites with relatively excellent scraping properties were prepared,and the scraping resistance of the materials was improved on the basis of balancing and improving its mechanical properties.The effects of wollastonite filler,nucleating agent and scratch resistant agent on the properties and microstructure of PP were studied.PP materials with better scraping performance were prepared by combining the mechanism of wollastonite strengthening and improving the scraping resistance,the nucleating mechanism of nucleating agent and the scraping resistance agent improving the scraping resistance of materials.Thus,the application of PP composites in automotive field can be further expanded.Here are the main results and contents of the study:(1)By using stearic acid and silane coupling agent(KH550/KH570/KH792)as composite surface modifier,wollastonite was modified to study the surface modification effects of different coupling agents on wollastonite.The results show that the modified wollastonite with the coupling agent KH550 has the best effect when the stearic acid content is 0.5%,and the contact angle is 145.55°,the activation index was 60.15%,the viscosity of wollastonite/liquid paraffin system decreased by7.5mPa.s.(2)The modified wollastonite was used as the inorganic filler and polypropylene SP179 as the substrate to study the modified effect of the modified wollastonite on PP.The results show that when the wollastonite content is 8%,the impact strength of the composite material rises steadily,the heat resistance is improved,the scratchresistance is improved obviously,and the processing fluidity is appropriate.(3)when the proportion of wollastonite is 8%,different proportion of scratch resistant agent is added to the PP substrate,and when the amount of scratch resistant agent is 1.5%,wollastonite in the composite material to better dispersion,grain refinement,crystal perfection.The crystallization curve of the composite material moved towards high temperature,and the crystallinity was the largest.The comprehensive mechanical property is the best,has the good processing flow performance,the heat resistance is good,guarantees the composite material excellent mechanical property and the good processing performance.The surface friction coefficient of PP decreased by 35.1%,the color difference decreased by 25.2%,the hardness was also improved,and the scratch resistance was significantly improved.The results show that the anti-scratch agent has a positive effect on improving the dispersion of wollastonite and they can have a synergistic effect.(4)When the proportion of wollastonite is 8%,and the nucleating agent is added to the PP substrate,the modification effect of the nucleating agent combined with modified wollastonite modified PP is studied.The results showed that: when the nucleating agent content was 0.2%,the grain size was refined,the crystallinity was improved,the spherulites were arranged more closely,the surface hardness of the material was significantly improved,the impact and other properties of the composite were improved,the friction coefficient and color difference were decreased,and the scratch resistance was significantly improved. |
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