Highly Filled Composite Materials Based on UHMWPE and a Mixture of Micron and Nanoscale Aluminum Particles

Highly filled (up to 90 vol %) UHMWPE composites with Al of controlled dispersed composition (micro-, nanoparticles, and their mixtures) were obtained by the polymerization filling method. The use of a mixture of micro- and nano Al particles predominantly containing micron-sized particles allowed us to achieve a denser packing of heat-conductive particles in the polymer matrix and create more efficient heat-conductive paths in compressed specimens, in comparison with the composites containing only the micro- or nano Al particles. The thermal conductivity achieved with a mixture of nano/micro aluminum particles in the ratio 30/70 was 9.7 W/mK at 82 vol % degree of filling. The enhanced thermal conductivity of the materials goes together with high electrical insulating properties (σ dc not higher than 10 –9 S/cm) due to the presence on Al particles, in addition to thin oxide coating, also a coating of UHMWPE. The high thermal conductivity and electrical insulating properties of the obtained UHMWPE composites are combined with high strength properties under compression. At total aluminum concentrations up to 80 vol %, the pressed specimens do not collapse under compression, and have significantly enhanced modulus of elasticity under compression and strength at the yield point compared to UHMWPE. It is the combination of the UHMWPE matrix and the polymerization method for incorporation of fillers into it, including nanosized ones, that makes it possible to obtain highly filled composite materials with a high level of functional and mechanical properties.