摘要
以聚酰亚胺(PI)为主体材料,添加少量的石墨和聚四氟乙烯,通过挤出成型工艺得到PI复合颗粒。并进一步注塑成型为汽车用止推垫片,主要探讨了注塑成型温度和压力对其成型性能和力学性能的影响。结果表明,随着注塑温度升高,PI试样的拉伸强度、冲击强度和压缩强度都提高,当注塑温度超过360℃时,力学性能有所下降,注塑温度过高或过低都会使试样性能下降;在合适的注塑温度下,适当提高注塑压力,有利于提高试样的力学性能。最佳的注塑工艺条件为:注塑温度为360℃,注塑压力为120~150 MPa。对在最佳工艺条件下注塑的PI试样,用退火的方式进行热处理,发现在200℃时处理30 min,试样的力学性能最佳。通过优化注塑成型工艺制备的汽车用止推垫片性能优异、耐温性好、抗蠕变强、耐磨性佳、耐油性好、力学强度高,而且阻燃性能优异,完全符合汽车用止推垫片性能要求。
By using thermoplastic polyimide(PI) as the matrix and some graphite and PTFE,the composite pellets were made through extrusion process. Taking these pellets as raw material for injection molding into thrust washer,the effects of injection temperature and pressure on the molding properties were also investigated. The results show that with the increase of the injection temperature,the tensile strength,impact strength,and compressive strength of the TPI samples molded increase. When the injection temperature is above 360℃,the mechanical properties of the samples molded decrease. As the injection temperature is fixed at 360℃,increasing the injection pressure can improve the molding properties. The optimal injection molding conditions of TPI are that the injection temperature is 360 ℃,and the injection pressure is 120~150 MPa. The samples molded under the optimal injection conditions were treated by annealing method. It is found the optimal annealing process is putting the samples molded at 200℃ for 30 min. At last,the thrust washer samples of the automobile vehicle were produced at the optimal injection molding condition. The properties of the products were also investigated. The Thrust washers have high temperature performance,low thermal expansion coefficient,low friction coefficient,excellent oil resistance,good mechanical properties,and excellent flame retardant. In a word,the thrust washers molded meet the requirements for the automobile vehicle.
引文
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