Processing of reactive acrylic thermoplastic resin at elevated temperatures for rapid composite and fiber metal laminate manufacturing

Thermoplastic polymers are increasingly being used as matrix materials for composites because they offer the advantage of recyclability and joinability over thermoset matrix systems. The polymerization kinetics and gas formation of different precursor mixtures of the liquid acrylic matrix system Elium ® were investigated with different initiator contents and at different temperatures for accelerated processing of composites and fiber metal laminates. The mechanical and thermal properties of the resulting polymers showed no significant difference between the investigated parameters. However, the polymerization time was successfully reduced to under 15 minutes with higher temperatures and initiator contents in laminates with 1 mm thickness. In bulk polymerization and thicker laminates, the right parameters must be chosen to balance polymerization time and matrix heating to avoid gas formation leading to voids in the matrix. A combination of 75 wt% Elium ® 130 and 25 wt% Elium ® 190 with 1.25 wt% peroxide initiator at 50 °C was found to be optimal for reducing gas formation while simultaneously accelerating the polymerization reaction in 3-5 mm thick layers.