Resin transfer molding of composite materials that emit volatiles during processing

A method for resin transfer molding thermoplastic composite parts, comprising:

• thinning an unpolymerized thermoplastic resin with a volatile solvent to a viscosity at which the resin may be injected into a mold having a cavity that establishes the dimensions of the composite part;
• injecting the thinned resin into the cavity;
• heating the resin to a temperature at which the resin polymerizes;
• further heating the resin to an elevated temperature at which the resin emits volatiles;
• withdrawing the volatiles, including the solvent, at the elevated temperature from the cavity;
• and
• placing a consolidating pressure on the resin to form the composite part.

An apparatus for resin transfer molding a composite part formed of a resin that emits large volumes of gaseous volatiles during processing, the apparatus comprising:

• a tool having a cavity that defines the dimensions of the composite part;
• an injection pump that injects the resin into the cavity;
• one or more porous tool inserts located in the cavity, the porous inserts allowing volatiles produced by the resin to flow through the inserts and out of the cavity;
• an evacuation system for withdrawing the volatiles through the porous inserts and out of the cavity;
• and
• a heater for heating the resin within the cavity to a temperature at which the resin emits volatiles.

An apparatus for resin transfer molding a fiber reinforced thermoplastic composite part, comprising:

• (a) a tool having an interior cavity that establishes the dimensions of the composite part, the tool being movable between an expanded configuration and a contracted configuration, the interior cavity having a reduced volume in the contracted configuration;
• (b) means for injecting the thermoplastic resin into the interior cavity;
• (c) a heater for heating the thermoplastic resin to a temperature at which volatiles are emitted from the resin;
• (d) means for withdrawing the volatiles from the cavity;
• and
• (e) means for consolidating the thermoplastic resin by moving the tool from the expanded to the contracted configuration.