Reseaches On Properties Of Glass Fiber Reinforced Nylon66Used In High-speed Rail

In this dissertation, glass fiber reinforced nylon66(GF/PA66)confirming to the high-speed railway technology indicators wasprepared by intermeshing twin-screw extruder. The effects of screwcombination, parameters of injection molding process, glass fiber (GF),and flexibilizer on the properties of GF/PA66were also investigated.The main results are as follows:The choice of composites matrix would affect the final properties ofthe composite, so, the properties of the matrix and the compatibilitybetween it and its addition agents must be considered. Differentflexibilizer will bring different toughening effects to PA66, andresearches found that maleic anhydride grafted styrene-(ethylene-butylene)-styrene block copolymer (MAH-g-SEBS) is an effectiveflexibilizer to PA66. GF/PA66composites were tested by tensilemachine, scanning electronic microscop (SEM), and polarizing opticalmicroscope (POM). The results bring out conclusions as follows: GFcould enhance the tensile strength, flexural strength, notched impactstrength, and Rockwell hardness of GF/PA66composites, without reducing the melt point of it. MAH-g-SEBS could improve the interfacestatus of the blends,bring GF to form a better dispersion in PA66matrix,and improve the impact strength of the material, but bring downthe tensile strength and flexural strength. Both GF and MAH-g-SEBSreduced the melt flow index (MFI), leading the material to poor meltflow ability, then affected the processing properties of the material. Onlythe ratio of each component is appropriate, the comprehensiveperformance of GF/PA66composites would be the best.The choice of screw combination is determined by the properties ofthe material, only the best screw combination can produce goodperformance composites. Parameters of injection molding process likeinjection speed, melt temperature, back pressure, and the pressure ofholding pressure affect the properties of products directly. Appropriateprocess parameters are the basic requirements to produce goodperformance products.