POST-MOLDING SHRINKAGE CHARACTERISTICS OF SOME THERMOSETTING PLASTIC MOLDING MATERIALS

The dimensional stability as to post-molding shrinkage of commercially available melamine, phenolic and polyester plastic molding materials was investigated by means of accelerated conditioning procedures which produced shrinkage corresponding to that obtained on parts in service in long-time aging. It is concluded that of the materials tested, the polyester mineral filled molding material demonstrated the greatest degree of dimensional stability.