Injection Molding and Properties of Highly Filled Copper-Polyamide 11 Composites

Abstract

Copper-polyamide-I1 composites containing up to 90 wt.% of spherical copper powder were made using three approaches: (1) conventional injection molding of dry copper-polyamide powder blends, (2) compounding of powder blends and subsequent injection molding of composite pellets, and (3) direct molding of powder blends on an injection machine equipped with a vacuum hopper. The conventional molding of powders results in products having a significant porosity, which originates from the air dragged into the machine with the powder. The other two approaches can be used to produce essentially void-free materials. The mechanical properties are affected by the state of the filler surface. The "as-atomized" copper (which has a rough surface covered with an oxide layer) adheres better to the polymer than that whose surface was reduced to pure metal by hydrogen.