Study And Development Of Aramid Fiber Knitted Fabric Composites

Composite material is a type of material that has unitary construction and high performance,which is composed of two or more types of properties and phase materials using appropriate methods.Composite manufacturing technology which using the two or more different types,different properties and phase materials to manufacture overall structure systems and the performance is excellent,which is called "appropriate method or technology." The reinforced materials of composite materials are commonly used glass fiber,aramid fiber,carbon fiber,high tensile polyethylene fibers and its fabrics.The aramid fiber has high strength,high modulus,low density.The aramid fiber knitted fabric can be combined with resin to develop high performance polymer composites.This paper describes the research and development of aramid fiber knitted fabric reinforced composite materials,including the surface modification of aramid fiber with chemical methods,the knitting of aramid fiber reinforced knit braid,the preparation of aramid fiber knitted fabric reinforced composite materials,the test and characterization of stretching,bending,compression performance of the composites and the preparation and characterization of helmet.Firstly,using molecular sieves anhydride and KH550 triethoxysilane agent to modify the surface of aramid fiber,and the time,temperature,the concentration of KH550 triethoxysilane agent were employed as single factor.According to the test of aramid fiber and resin composite IFSS,the optimum method is 9h,45 ? and the concentration of KH550 triethoxysilane agent is 20%.And scanning electron microscopy,infrared spectroscopy,single fiber angle measurements and X-ray diffraction instrument were used to analyze the surface microstructure changes in the functional groups,changes in the hydrophilic property and crystallinity of aramid fiber before and after treatment.Secondly,it introduces the knitting principle of hand-knitting machine,and the full gauge 1×1 rib and milano rib was used as the basic stitch to conduct the stitch design,then knitting the reinforced composite material on hand-knitting machine.The weft plain stitch was used as the basic stitch to knit helmet by retractable needles.Thirdly,the full gauge 1×1 rib and milano rib of aramid fiber knitted fabric was used as reinforcement,the E51 epoxy resin matrix and flat-panel curing machine were also employed to prepare aramid fiber knitted fabric reinforced composite.Through several tests,the optimum process is resin and curing agent ratio 160/90,heating time 2h,holding time 2h,temperature 50 ?,pressure 2.0MPa.The thickness of the aramid fiber knitted composite sample was 4mm.Then,using the strength tester to test the stretching,bending and compression performance of aramid fiber knitted fabric composite material.By analysis of experimental results,the warp-wise and weft tensile strength improvement rateof aramid fiber knitted fabric with full gauge 1×1 rib and milano rib stitch is 42.063%,38.826% and 47.786%,36.826% respectively,after the treatment by KH550 ?-aminopropylsilane coupling agent.The warp-wise and weft bending strength improvement rate of aramid fiber knitted fabric with full gauge 1×1 rib and milano rib stitch is 36.214%,47.426% and 32.998%,42.218% respectively,and the compression strength of them is46.953%,33.387% and 45.401%,32.082%,respectively.Finally,the hand-paste method was used to make the helmet of aramid fiber knitted fabric reinforced.And then the quality,size,coating adhesion,flame retardant properties of helmet were tested and analyzed.By analysis,the experimental results obtained: the coating adhesion and flame retardant properties is excellent.It can be used to build high strength helmet of motorcycle racers.It is 61 figures,32 tables and 126 references in this paper.