Waste tire rubber based magnetorheological elastomers

Abstract

The High-Pressure High-Temperature (HPHT) sintering is an established process for reclaiming Waste Tire Rubber (WTR) into Magnetorheological Elastomers (MREs). Even though the WTR is generally recycled to other products, the usage of WTR as the main matrix of MRE is a new and novel concept. Therefore, this research focuses on studying the physicochemical and viscoelastic properties of the WTR based MRE produced through HPHT process. The WTR, carbonyl iron particles, and additives were mixed and compacted by applying simultaneous temperature and pressure at 200oC and 25 MPa, respectively. Swelling test, morphological examination, infrared spectroscopy, magnetization, and thermal analysis were among the physicochemical properties studied. Meanwhile, the magneto-induced viscoelastic properties were assessed through shear mode test in both steady and dynamic conditions. The highest degree of reclamation based on swelling test, achieved up to 54 % confirming that crosslinking occurred during reclamation process. The dispersion of the magnetic particles were examined through Scanning Electron Microscopy (SEM) and the morphology of the fractured matrix indicated that the WTR blended well without any grain boundaries of uncured WTR. The highest magnetization saturation was achieved at 76.079 emu/g. While, the infrared spectroscopy identified rubber substances including synthetic and natural rubbers based on the band characteristics. Additionally, the thermogram patterns and decomposition rates of the samples also approved the matrix composition. The glass transition temperatures were also measured at -60.6 ±0.5oC showing conformity with the reclaimed pure WTR. The WTR based MRE achieved maximum static stress ranging from 9 to 13 kPa (at 700 mT) with Linear Viscoelastic (LVE) region above 3% strain amplitude. The MRE exhibited MR effect up to 24 % with the range of storage modulus between 0.6 to 0.74 MPa (at 700 mT). Based on the examination results, the WTR based MRE demonstrated acceptable physicochemical characteristics and presented outstanding viscoelastic properties for future potential applications of MREs.