INJECTION-MOLDING AND PROPERTIES OF HIGHLY FILLED COPPER-POLYAMIDE-11COMPOSITES

Copper-polyamide-11 composites containing up to 90 wt.% of spherical c opper powder were made using three approaches: (1) conventional inject ion molding of dry copper-polyamide powder blends, (2) compounding of powder blends and subsequent injection molding of composite pellets, a nd (3) direct molding of powder blends on an injection machine equippe d 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 ca n be used to produce essentially void-free materials. The mechanical p roperties are affected by the state of the filler surface. The ''as-at omized'' 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.