Study on the process parameters and mechanical properties of thermoplastic sandwich panels with a vacuum infusion method

Abstract Thermoplastic glass fiber composites exhibit the advantageous characteristic of easy recyclability for both fibers and resin, which is beneficial to address the challenges associated with the recycling difficulties and environmental pollution stemming from traditional thermosetting composite materials. This paper proposes for the first time the preparation of PMMA thermoplastic resin/glass fiber (GF) + polyethylene terephthalate (PET) foam sandwich panels using a vacuum infusion process with a mixed resin of polymethyl methacrylate (PMMA) and methyl methacrylate (MMA). Taking PMMA number‐average molecular weight, PMMA content, and benzoyl peroxide (BPO) content as input variables, the quadratic regression models for the flat compressive strength (FCS) and lateral compressive strength (LCS) of the sandwich plate are obtained by the Box–Behnken experiment. The results show that the PMMA number‐average molecular weight has a larger effect on the compression strength of the sandwich panel. Using response surface methodology (RSM) prediction, it can be known that when the PMMA number‐average molecular weight is 1 × 10⁵, the PMMA content is 18.2 wt%, the BPO content is 0.52 mol%, and the N,N‐Dimethylaniline (DMA) content is 0.5 mol%, the vacuum‐filled sandwich panel has the best compression performance. In comparison to conventional epoxy thermosetting sandwiches, the FCS and LCS of PMMA thermoplastic sandwiches infused under optimal parameters have been enhanced by 7.64% and 7.83%, respectively. Highlights Vacuum infusion method of GF/PET/GF thermoplastic sandwich panels with PMMA + MMA binary liquid resin is proposed for the first time. The effects of the number average molecular weight of PMMA, PMMA content, and BPO content on the mechanical properties of the composites were investigated by response surface method. The technological parameters of resin preparation were optimized.