Shaped polymer fabrication reaction injection molding

The successful utilization of Reaction Injection Molding (RIM) to fabricate complex polyurethane shapes In a single step from relatively low viscosity streams has led to a search for other chemical systems which can be fabricated by the RIM process. The rapid polymerization of molten caprolactam by anionic catalysis has been utilized to develop attractive nylon RIM systems. The incorporation of a rubber segment In the polymer chain allows the fabrication of high Impact or even elastomeric nylon parts. The combination of a rubber phase with the high melting (215°C) crystalline nylon phase provides useful properties at low temperatures as well as at elevated temperatures. 

Processibility still remains a concern, since processibility appears to be much easier to obtain for undoped conducting polymers than for the same polymers in doped forms. If the polymer must be doped after fabrication of a shaped article, the problem of introducing the dopant uniformly is serieous, especially when it is required that the same dopant which easily diffuses into the article must eventually be thermally stable. What is needed here appears to be new methods for processing conducting polymers. One attractive possibility would be a process analogous to conventional RIM (reaction injection molding) in which polymer articles are directly fabricated from a mixture of monomer and dopant. 

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