Replacement of Commercial Carbon Black by Upgraded Pyrolytic Char in Solid Tyre Cushion Compounds

Abstract

Waste Tyre disposal is one of the most crucial environmental challenges in the world and Pyrolysis has been recognised as a sustainable solution to reduce the accumulation of waste tyres. Pyrolytic oil, gas, and char are the three primary by-products generates from the pyrolysis of waste tyres. The economic value of the pyrolytic char (PT-char) is low, and solid char disposal is difficult. Waste char could be given an economic value by being transformed to carbon black. The current study outlines a cost-effective method for producing commercial grade carbon black from low-grade PT-char. Prior to size reduction by ball milling and/or sieving, the pyrolytic carbon black was initially passed over a magnetic separator to remove metallic particles. These particles were demineralized at 60–80 ◦C for 1–2 hours with diluted acids and/or bases (2M HCl and 2M NaOH). CHN, XRD, SEM, and TGA were used to study the purity and surface properties of modified carbon char. Carbon content of char was improved after treating with two times in 2M HCl and once in 2M NaOH to ∼91 wt% (initial value of 67 wt%) while the ash content was decreased from 17.65% (w/w) to 3.59% (w/w). The removal of Zn from PT-char was confirmed by XRD and surface modification was confirmed by SEM images. The upgraded PT-char was used as reinforcing filler for the preparation of solid tyre cushion compounds. The rheological and physico-mechanical properties of the PT-char compounds were evaluated and compared with commercial grades of carbon black; N330, and N660. It was found that the rubber compounds prepared using purified PT-char do not significantly differ in their tensile strength, tear strength, and hardness from samples prepared using commercial carbon black grades. However, compression set shows the little lower values compared to commercial grade carbon black. Due to the effectiveness and efficiency of the upgrading procedure, it can be concluded that the upgraded PT char has a high potential to be used as cost-effective reinforcement filler in the rubber industry and solid tyre sector.