Car Interior Scratch Resistance And Dissemination Characteristics Of Polypropylene Composite

Polypropylene plays a vital role in the development of lightweight vehicles due to its low density and excellent physical and chemical properties. The quality of interior trim is the highlight which shows the rating of a car. A good automotive interior trim part should make people feel comfortable, have a nice appearance, be environmental friendly, and provide wonderful protection for the passengers. The material that is applied in the automotive interior trim parts should be well balanced in rigidness and toughness, and should have a good dimensional stability and long-term reliability. Besides, the material should not release hazard substances. The application of scratch-resistant material could dispense with surface coating of parts, improve the appearance and reduce the use of solvents, thus benefits the in-car air quality.However, the crystallization of polypropylene will lead to the poor low-temperature impact behavior of the material, and the product tends to warping after mold release. The relatively low surface hardness of PP copolymer makes it easy to be damaged by a sharp object, which is not conducive for the part to maintain its good appearance. PP releases a certain amount of volatile organic compounds (VOCs) at high temperature. Such VOCs are generated from the catalyst, residuals of peroxide and short-chain oligomers. This makes PP a source of in car air pollution. Thus PP must be well modified before it is applied in the automotive interior trim parts.In this paper we started from the blending modification of polypropylene and studied the improvement of impact resistance by different surface processings of talc. Mechanical tests show that talc particles wrapped by the elastomer leads to the expected balance between rigidness and toughness.We prepared PP composites with relatively low VOCs by screw devolatilizing technique, which could meet the VOCs requirements for automotive interior trim parts.Erucamide was used as a low cost smooth agent to improve the scratch-resistance of PP composites. A series of Erichsen cross cut tests on various surface grains were conducted and the corresponding scratch mechanism was also proposed. The results show that Erucamide effectively improved the scratch resistance of PP/POE/Talc composites by forming a thin lubricant layer on the surface of the material. The introduction of Erucamide did not cause deterioration of both mechanical properties and VOCs emission level.High temperature ageing test and accelerated UV exposure test were also conducted to test the weatherability of the PP composites. The results show that Erucamide remained stable after the accelerated weathering tests, exhibiting long-term scratch-resistant effect to the composites.In conclusion, the PP composite, prepared by blending with talc master batch, POE elastomer, Erucamide as anti-scratch additive, reveals expected mechanical properties, low VOCs level, excellent scratch resistance and weather resistance. Meanwhile, the composite also has a low-cost feature, exhibiting an intriguing application prospect in the field of automotive interior trim parts.