Vacuum-assisted microwave processing of glass-epoxy composite laminates using novel microwave absorbing molds

For polymer composite product manufacture, curing is a critical step in achieving desired thermal and mechanical properties. The conventional thermal cure processes using hot air ovens and autoclaves are time and energy intensive. Microwave (MW) assisted curing is one of the alternative, most promising methods of curing polymer matrix composites, that could lead to substantial reduction in cure cycle time, energy requirements and operational costs due to its volumetric mode of heating. In the present work, studies were carried out on vacuum assisted microwave curing of glass-epoxy composite laminates using novel, in-house fabricated, silica based microwave susceptible molds inside a conveyor type microwave cure facility. Comparison of the cure process parameters with those of conventional thermally cured composite laminates revealed that vacuum assisted microwave curing resulted in approximate to 90% time savings and approximate to 60% energy savings, thus revealing the dual benefits of microwave processing as well as the novel microwave susceptible molds employed. The temperature uniformity of the molds as well as the curing laminate was assessed using a non-invasive, thermal imaging camera. Cure completion of microwave-cured laminates was ascertained by glass transition temperature (T-g) measurements across the laminates as well as mechanical property determination. T(g)s as well as the mechanical properties obtained for vacuum assisted microwave-cured laminates (VMCL) were comparable or superior to those of thermally cured laminates (THCL). POLYM. COMPOS., 39:1152-1160, 2018. (c) 2016 Society of Plastics Engineers