An emerging, energy-efficient cure process for rapid composite manufacture

Two types of bi-functional epoxy-amine matrix systems (one room temperature -RT cure type13; and one elevated temperature -ET cure type), used for aerospace composite applications, were cured at the13; sample mixture level, composite laminate level and representative component level using three different13; multimode, microwave (MW) cure equipment viz., a domestic MW oven, a laboratory scale MW set-up and13; conveyor-type MW facility respectively, all of them operating at a frequency of 2450 MHz.. MW cure schedules13; equivalent to supplier-specified thermal cure schedules were individually evolved, using the glass transition13; temperature (Tg) as the index of cure completion. The glass transition temperature (Tg) values of MW cured13; samples were equivalent or slightly superior to respective thermally cured samples. The cure status and cure13; uniformity were assessed using differential scanning calorimetry (DSC) and confirmed through thermal imaging13; techniques. For the MW cured glass-epoxy laminates, the mechanical properties determined, compared well with13; or were superior to those of the thermally cured counterparts. Further, the microwave curing process, per se,13; resulted in a significant reduction in the process cycle time and energy consumption. In order to investigate the13; versatility of microwave cure, preliminary cure trials were performed at representative component level viz., for13; a 15mm thick laminate, a sandwich panel and a curved radome profile.