| Nylon 6 structural foam with a density of 0.51 g/cm$sp3$ was produced using an exothermic blowing agent by injection molding. Although a 55% reduction in density of Nylon 6 was achieved, the resulting cell structure was bad. Incorporation of nucleating agents considerably improved the cell structure, although elimination of voids could not be achieved. The use of a blend of exothermic and endothermic blowing agents, along with nucleating agents and optimum processing conditions, dramatically improved cell structure with complete elimination of voids. It was found that processing variables had a profound influence on the nucleation and growth of gas bubbles and, as a consequence, on the cell structure of the molded specimen. The molded specimens with good cell structure exhibited excellent solvent resistance. |
