RECYCLING OF WASTE RUBBER POWDER AND MICRO-PARTICLES AS FILLER OF THERMOSETS - ABRASIVE WEAR

Recycling of waste is still a current issue - saving primary sources and energy should be a priority. Inexpensive recycling which is environmentally friendly should be preferred. The EU Waste Management is focused on the material recyclation of waste. One of the ways of the material recyclation of waste rubber powder and micro-particles is their inclusion into polymeric materials - thermosets are suitable examples. The waste rubber powder (average dimension 23.8 µm) and micro-particles (average dimension greater than 955.6 µm) were gained as outputs of the recycling line which handles tyres and rubber waste generated in the automotive industry. The recycling of rubber tyres is important in relation to the environment. Thermoset was represented by the two-component epoxy resins (PU resin was also used). The combination of the polymeric matrix and the waste filler gives birth to qualitatively brand new materials - polymeric particle composites. Adding waste to thermosets decreases their price and changes their mechanical properties. The testing samples were prepared with 5, 10, 15 and 20 vol.% of the waste filler. The variable filler concentration can describe the influence of the concentration on the resultant mechanical properties. The paper deals with two-body abrasion wear, hardness, density and porosity of such composites. The two-body abrasion was tested on a rotating cylindrical drum. The experiment results quantify the mechanical properties and can help expand the application area of filled systems. Composites are materials which combine the properties of the matrix and of the filler. As filler inorganic and organic micro- and nano-particles can be used. If micro-particles are used as a filler and a polymer material as a matrix, we can speak about polymeric particle composite systems. The mechanical properties of these systems depend on the mechanical and physical properties of the individual phases and their mutual interaction. The micro-particles can also improve the range of mechanical properties. Kim et al. (1) and Park et al. (2) increased the abrasive wear resistance of resin without the filler by inclusion of nano-particles. Basavarajappa et al. (3) describe in their experiments a significant positive influence of SiC micro-particles on the three-body abrasive wear resistance of the polymeric matrices. The resistance to abrasive wear can be increased by using different types of micro-particles based on waste. Valasek et al. (4-6) used in their experiments hardfacing alloys from the machining process and synthetic corundum (micro-particles) which was taken from a sand blaster. These materials showed higher hardness and higher resistance to abrasive wear. The rubber micro-particles can be also used as a filler of polymers. E.g., Cerbu and Curtu (7) describe improving the impact strength of polymers just by the presence of recycled rubber particles. Subramaniyan et al. (8) improved mechanical properties of polyurethane foam filled with Kenaf fibres by recycled rubber particles. The aim of the performed experiment was to describe the abrasive wear resistance of epoxy resin and polyurethane resin with waste rubber micro-particles which were taken from a line devoting to an ecological liquidation of tyres. The waste rubber comes into being as one of products just during the ecological liquidation of tyres. The rubber waste particles are of different sizes and they find their application, e.g., in an area of sports surfaces or panels which are used for lowering noise etc. The experiment describes the abrasive wear of filled epoxy resin and its hardness. It reviews mutual interaction of rubber particles of various sizes and the epoxide. So far, as breaking of micro-particles has occurred during the abrasion, this material would not be suitable for putting on various surfaces of materials. As Valasek et al. (9) state that rubber micro-particles need not decrease the shear strength of epoxy resins, that is why the filled epoxy resins can be used for cementing and adhesive bonding of greater units, where they can also have damping impacts on the surface of a part. They can be exposed more or less to the abrasive wear in some of these applications.