In situ barrier layer formation for coinjection resin transfer molding

Coinjection resin transfer molding (CIRTM) requires all impermeable barrier layer to prevent undesired mixing of resins injected into the mold. This study involves in situ formation of this barrier layer using a thermoplastic polyester powder binder attached to a fabric during the preforming stage. The powder binder is sprinkled onto the glass fabric and melted by use of heat and pressure, to form the separation layer. A number of factors such as preforming temperature, pressure and time that govern the spread of individual binder particles into a film and the subsequent impregnation into the fabric are evaluated. Lateral spread of particles oil nonporous substrate is studied and verified. A series of models are used to predict the impregnation of the binder melt into the fabric at the given preforming conditions. The optimized preforming conditions for impermeable film formation were determined for a biaxial weave fabric. Coinjected laminates using the in situ barrier layer were manufactured and their performance was shown to be comparable to conventional CIRTM laminates using the short beam shear test.