The Use of Waxes and Wetting Additives to Improve Compatibility Between HDPE and Ground Tyre Rubber

Abstract

The concern about the amounts of used tyres that end in landfills and the environmental problems that they produce have led to research on ways to use these residues in common applications. A general starting point in the recovering procedures is the grinding of the tyres in order to obtain a powder known as ground tyre rubber (GTR). This paper proposes an alternative way of recycling the used tyres by means of a new material composed by a polyolefin matrix, high-density polyethylene (HDPE) reinforced with GTR. The crosslinked structure and surface characteristics of the GTR hampers good interaction with the polymeric matrix, leading to weak adhesion between the two phases and consequently a decrease of the mechanical properties. The aim of this work is to improve adhesion, achieving better wetting of GTR particles by HDPE. For this purpose, waxes and wetting additives were added to the mixture. The influence of these additives was determined by mechanical properties, attenuated total reflection infrared spectroscopy, differential scanning calorimetry analysis, scanning electron microscopy, and optical microscopy. An acidic wetting additive and a polyethylene wax showed good results regarding mechanical properties, dispersion of the GTR particles and adhesion.