Development and Analysis of an In-Mold Coating Procedure for Thermoplastic Resin Transfer Molding to Produce PA6 Composites with a Multifunctional Surface

We have developed a complex Thermoplastic Resin Transfer Molding procedure to create polyamide 6 composites and their multifunctional coatings in a single production cycle with low cycle time. The advantage of the new process is that it has low emission of volatile organic compounds due to the closed mold and the products can be recycled easily, decreasing the negative impact on the environment. In addition to developing the process steps and parameters, we produced samples with different curing time and fabric content of the base layer, waiting time before coating injection, surface thickness and titanium dioxide content of the surface layer. Then we analyzed the adhesion between the surface and base layers and the warpage of the complex part. SEM analysis proved that the reinforcement fabrics could be properly impregnated with the reactive thermoplastic system during the production of the base layer. Furthermore, we showed that the strength of the interlayer bonding can be improved when the base layer is properly polymerized in the first step. Using our method developed to assess warpage, we demonstrated that the warpage of the base layer can be reduced by applying the appropriate manufacturing parameters to the surface layer.