Effects of accelerated curing in thermoplastic particle interleaf epoxy laminates

Faster heating rates of 10 degrees C/min and higher process temperatures of 210 degrees C were applied to the commercial M21 resin system. The total process time was reduced by two-thirds while achieving the same degree-of-cure in the epoxy. Thermal analysis and hot-stage microscopy showed that the thermoplastic interleaf particles melt at around 15 degrees C above the manufacturer's recommended 180 degrees C curing temperature. A short dwell at 180 degrees C was found to prevent the thermoplastic particle from mixing with the thermoset pre-polymer before ramping to the accelerated curing temperature of 210 degrees C. Such interaction was found to decrease the glass transition temperature by 13-45 %, but increase the mode I delamination resistance by 70-105 %, respectively. The results demonstrate that accelerated curing of interleaf systems can shorten cycle time and produce a range of physical and mechanical properties from a single base material, opening the design space to new and optimised composite structures.