A Study on Weight Loss Rate Controlled Binder Removal From Parts Produced by FDC

Abstract

The binder removal schedule of a binder in the ethylene vinyl acetate-wax system was analyzed by automatically adjusting the soaking duration based on the monitored weight loss of the polymer. The thermolysis of several grades of microcrystalline wax and ethylene vinyl acetate have been analyzed by TvA and DSC to support the explanation of the weight loss rate controlled binder removal experiments. During the thermolysis ofsuch binders in air, the degradation sequence is degradation and evaporation of hydrocarbons, degradation ofthe vinyl acetate, and degradation of the ethylene chain, all oxygen assisted. It was shown that the extent and the rate of the vinyl acetate degradation in air is determined by the molecular weight of the EVA, unlike its degradation in N2• It was concluded that thermolysis of light polymers is easier than that ofthe heavy ones and weight loss rate controlled binder removal technique can help in the optimization of binder removal schedule for a variety of polymers.