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We have investigated composites containing metallic micro-size and nano-sized particles as the 10 wt% dispersed phase. Branched low density polyethylene (LDPE) was the matrix. Microsized metals were Al, Ag and Ni; nanosized metals were Al and Ag. Several mechanisms of wear are observed in function of the kind and size of metal used: deformation, delamination, abrasion, adhesion and rolls formation. The presence of Ag particles increases the wear rate as compared to neat LDPE. The presence of Al particles lowers the wear of LDPE significantly; nanoparticles are more effective than microparticles.

The polymers used as a matrix were low density polyethylene (LDPE) and a thermoplastic elastomer (TPE). The metal particles were Al, Ag, and Ni with micrometer diameters. The metal concentration varied from 0 to 10 wt%. Dynamic and static frictions on tetrafluoropolyethylene and stainless steel as sliding surfaces were determined and tensile tests were performed. Secondary electron and backscattered electron SEM images were taken to determine microstructures of the hybrids. Addition of metal powder to the matrix results in reduction to a minimum of the tensile elastic modulus for low metal concentrations, and increase in the modulus with further addition of metal particles. For the TPE, the tensile modulus exceeds that of the pure material. Small metal particles increase the modulus at lower concentrations than larger ones. Hardness varies with the filler concentration, similarly as tensile modulus does. Backscattered electron SEM images show uniform dispersion of the metal particles at the surfaces and in the bulk. The contrast is enhanced by large differences in atomic numbers between the fillers and the matrices. Ni microparticles in LDPE cause crack arrest seen in SEM. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

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