Influence of water during manufacturing of APA6 in the thermoplastic RTM process

Abstract

The thermoplastic resin transfer molding (T-RTM) process has the potential for high-volume production of high performance fiber-reinforced components in the automotive industry. The fast anionic polymerization of APA6 and the development of robust injection equipment lead to short cycle times. The sensitivity against water of the reactive APA6 is well known. All resin components from the manufacturer are dried to achieve water content below 200 ppm. In T-RTM high-performance composite manufacturing fibers, binder systems or core materials are needed. During the manufacturing (preforming, handling, infiltration) of these materials it is necessary to ensure that the total amount of water is small enough to achieve good polymerization. Previous studies established the influence of water for non-activated polymerization. However, there is no knowledge about the influence of water during T-RTM manufacturing using fast-reacting activated polymerization. In this paper, different concentrations of catalyst are investigated to analyze the influence of water in the T-RTM process during curing of the resin. Residual monomer content and viscosity number was measured to analyze the conversion of manufactured plates. To characterize the impact on the mechanical properties, tensile tests were performed. The results show the possibility to monitor the anionic polymerization during the manufacturing by observing the trend of the cavity pressures. In addition, the influence of water on the conversion and the resulting mechanical properties can be compensated by the concentration of the catalyst