Preparation And Study Of Nylon/Kevlar Fiber Composites

With the outstanding performances such as high strength, high modulus, small density, insensitive gap and good heat resistance, Kevlar fiber is widely used in high-tech areas such as aviation and astronautics. Nylon has many excellent performances, such as high mechanical strength, good toughness, wear resistance etc., can be used widespread. But nylon still exist some defects like moisture absorption resistance, poor Resistant of strong acids and strong alkaline, poor dimensional stability and low heat distortion temperature, which greatly limit its use. Kevlar fiber reinforced nylon composites can obtain high strength, good heat resistance, dimension stability performances. But in Kevlar fiber reinforced composites the adhesion between Kevlar fiber and nylon matrix is poor. It needs to improve the adhesion between Kevlar fiber and nylon to obtain better physical and mechanical properties. In this paper. nylon/Kevlar fiber composites are prepared by different methods using nylon6and nylon66as nylon matrix respectively. The preparation methods and results are as follows:1. Nylon6/Kevlar fiber (PA6/KF) composites were prepared in autoclave using in-situ polymerization. Mechanical properties and heat distortion temperature (HDT) were tested, and also were characterized by SEM, DMA, TGA and XRD. The research show that the tensile strength, flexural strength, HDT of the composites raised greatly, as a maximum of75.3MPa.72.1MPa.109℃. improving by49.4%,75.4%and145%respectively, the adhesion between PA6and Kevlar fiber was improved, the storage modulus and heat resistance improved with the increasing content of Kevlar fiber, an interface peak appeared at the high temperature side of Tg.2. Nylon66/Kevlar fiber (PA66/KF) composites were prepared using twin-screw extruder. Phenoxy was added into PA66/KF composites to prepare PA66/KF/PHE composites. The addition of phenoxy improved the adhesion between nylon66and Kevlar fiber. Mechanical properties and HDT results show that:after addition of10wt%aramid fiber in nylon66. tensile strength and flexural strength of the composites increased from78.2MPa and96.3MPa to84.3MPa and104Mpa respectively, and heat distortion temperature increased from83℃to135℃. Adding a small amount of Phenoxy in PA66/KF composite, the tensile strength and flexural strength increased slightly, while its heat distortion temperature increased from135℃to168℃. Scanning Electron Microscopy (SEM) results show that: the addition of phenoxy improved the adhesion between nylon66and Kevlar fiber, the pulled out fiber was attached with nylon66, Kevlar fiber and nylon66bonded closely. The interface performance of PA66/KF/PHE composites was good, hindering the movement of nylon66 chains, an interface peak appeared at the high temperature side of Tg of PHE.