Nylon 6/copper composites by in situ polymerization

Composite materials based on nylon 6 (PA6) and unmodified copper particles, were prepared by in situ anionic polymerization of e-caprolactam (CL) in the presence of the metallic fillers using rotational moulding technique. The above materials were characterized by some experimental techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray diffraction (WAXD). The electrical conductivity and mechanical properties of the composites under study were also evaluated. Both molecular weight and crystallinity of the nylon 6 matrix were found to be strongly influenced by the presence of the copper powders. WAXD analysis has evidenced a close relationship between metallic filler used and nylon 6 crystal structure. The presence of copper particles into nylon 6 favours the formation of gamma-phase crystal and reduces the fraction of the a-form crystal. For the copper particles incorporated in the nylon 6 matrix only one main peak at 2 theta =43.4 degrees was observed. Analysis of the results obtained on nylon 6/copper composite materials with DSC show that the incorporation of copper particles lowers the melting temperatures but rises the crystallization temperatures of the matrix of the composites while its crystallinity degree decreases. The addition of metal particles to nylon 6 played the role of nucleating agent and enhanced the crystallization rate. An improved thermal stability of the nylon 6/copper composite materials with respect to the neat nylon 6 can be noticed. The investigations on the nylon 6/copper composite materials show also that their mechanical properties are superior to those of neat nylon 6 in terms of the flexural strength and flexural modulus, but with sacrificing their impact strength.