Multi-Stimuli frontal polymerization of fiber distributed Polymeric composites for agile manufacturing

Widely used fiber-reinforced polymeric composites (FRPCs) require prolonged processing at high temperatures and pressure, limiting their adoption in agile manufacturing. We address the demand for rapid manufacturing by implementing the frontal polymerization process. We present the tunable cure kinetics of the frontal polymerization (FP), a self-propagating exothermic reaction process, enabling self-sustaining curing. We explain the effect of fiber microstructure on the radical-induced cationic frontal polymerization (RICFP) process which requires a dual initiator mechanism. RICFP allows an autocatalytic mechanism activated by UV and/or heat, generating free radicals that accelerate polymer chain formation. By using differential scanning calorimetry (DSC) and rheological analysis we have measured the influence of fiber reinforcement and chemical composition on the curing parameters of FRPCs. The results are used to develop a transient thermochemical computational model in finite element framework to simulate heat generation and front propagation. We have simulated heat generation by exothermic reaction to determine the degree of cure (DoC) and heat front propagation for different sizes and orientations of the fibers and physical properties of the resin. The insight gained into the impact of the material compositions on the thermo-mechanical properties will guide us in designing the extrusion and curing conditions for the DIW printing of FRPCs with disparate properties.