Injection Molding of Thermosetting Resins

The cure of thermoset resins involves the transformation of a liquid resin, first with an increase in viscosity to a gel state (rubber consistency), and finally to a hard solid. In chemical terms, the liquid is a mixture of molecules that reacts and successively forms a solid network polymer. In practice the resin is catalyzed and mixed before it is injected into the mold thus, the curing process will be initialized at this point. The resin cure must therefore proceed in such a way that the curing reaction is slow or inhibited in a time period that is dictated by the mold fill time plus a safety factor otherwise, the increase in viscosity will reduce the resin flow rate and prevent a successful mold fill. On completion of the mold filling the rate of cure should ideally accelerate and reach a complete cure in a short time period. There are limitations, however, on how fast the curing can proceed set by the resin itself, and by heat transfer rates to and from the composite part. 

Reaction-Injection Moiding System Liquid compositions, mostly polyurethane-based, of thermosetting resins, prepolymers, monomers, or their mixtures. Has good processibility, dimensional stability, and flexibility. Processed by foam molding with in-mold curing at high temperatures. Used in auto parts and office furniture. Also called RIM. 

Injection Molding. Both thermosetting and thermoplastic polymers can be used in the injectionmolding process, though the practical requirements are very different for the two types of polymers. In injection molding, a cavity in the shape of the desired object is filled with molten thermoplastic or a thermosetting prepolymer resin. When the sohd polymer has formed, the object is removed from the mold and... 

Applications include a wide variety of thermoset resins for injection molding and rubber compounds ranging from floor tiles to shoe soles. Dicaflock can be used as a plasticizer, bulking agent, arc intensifier, 2d>sorbent and lubricant. 

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