Electrical application of polyamide reinforced with old tire rubber (ground tire rubber)

Abstract

Mass production of tires and their subsequent storage after use is a serious environmental problem that is tried to be solved in various ways. One of these ways is the mixture of these old used tires (ground tire rubber (GTR)) with various thermoplastic and thermostable polymers. These blends are made by modifying the pretreatment the GTR is subjected to, the degree of devulcanization, the mixing or pressing conditions, etc. Later the mixtures are analyzed structurally and mechanically, looking for possible industrial applications for them. The present work aims to obtain materials suitable for the electric industry from the mixture of polyamide with old used tires (GTR), starting from the requirement of minimum recycling costs, that is using vulcanized GTR without any prior treatment but acting on the particle sizes with a simple and inexpensive screening. A novelty of this study is the large number of compounds analyzed, and the deep analysis these have been submitted to dielectric, mechanical, thermal and microstructure analyses to get a large number of variables in each test. Compounds were categorized as the three GTR particle sizes ( p < 200 μm, 200 <  p < 500 μm and p > 500 μm) and seven concentrations of GTR (0%, 5%, 10%, 20%, 40%, 50% and 70%), resulting in a total of 21 new compounds. In addition, in order to have the dielectric tests as much exhaustive as possible and to show the behavior of the compound under widely changing conditions, a wide range of temperatures (30–120°C) and frequencies (1 × 10−2 Hz to 3 × 106 Hz) were taken into consideration. All these data have provided an accurate characterization of the properties of the new compounds, and according to these results, possible electrical applications have been explored, with the requirement that they must comply with official regulations.