Publication: Development of rubber compound with bio-based oil and enhanced performance for green tyre tread application
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Date
2024-04-01
Authors
Nur Raihan, Mohamed
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Abstract
The purpose of this research is to create an environmentally friendly pre-cured tyre tread liner compound using a ternary rubber blend of natural rubber (NR),
butadiene rubber (BR), and solution styrene butadiene rubber (SSBR) filled with hybrid fillers of carbon black and silica. Prototype tyre tread liners were manufactured as the end-product and went for a trial run on the road using a single-axle 10,000 tonnes lorry provided by rubber manufacturer Eversafe Rubber Works Sdn. Bhd. A few studies have been performed, starting with developing new formulations by the alterations on blend and fillers compositions. The blend composition of NR/BR/SSBR (60/30/10) was used as the reference, which rubber manufacturers use to produce the all-season tyre. A design of new formulations for NR/BR/SSBR, 65/30/5 and 70/25/5, was proposed based on the existing blend composition. The 5-10 phr of additional NR has slightly increased tyre tread performance. The blend composition of 65/30/5 showed comparable results with lower wear resistance than the control sample, 60/30/10. Interestingly, the 70/25/5 composition displayed higher tensile strength. In the case of hybrid fillers, the compound with a CB/Silica ratio of 20/48 showed higher tear strength and M300%. Noting that filler compositions with a CB/Silica ratio of 12/56 produce an outstanding ratio for the wear resistance and skid resistance compared to control compound together with 28/40, additional increases in CB and decreases in silica loading can improve filler dispersion, as shown by the Payne effect. Further, the study focused on fully substituting bio-based oils in the compounds to replace the common practice of petroleum-based mineral oil. There are four bio-based oil proposed namely coconut oil (CO), sunflower oil (SFO), soybean oil (SBO) and Epoxidized Palm Oil (EPO). Among the proposed bio-based oil, EPO is selected due to its great value of skid resistance and a slight reduction in rolling resistance. In addition, EPO is considered the main natural resource in Malaysia and is readily commercialised by local industry. By altering the EPO content, the mechanical properties of the rubber compound, such as wear resistance, tensile strength, and hardness, were improved. Finally, the prototype tyre tread liner was successfully produced based on the specific formulation and labelled PT-1 (Prototype 1) and PT-2 (Prototype 2). PT-1 showed promising mechanical properties in tensile strength, tear strength and abrasion resistance. Similar mechanical properties are enhanced for PT-2 but with a slight reduction in abrasion resistance. According to the dynamic mechanical properties, both prototype tyres (PT-1 and PT-2) offered superior properties, with PT-1 obtaining a lower rolling resistance while PT-2 showed a slightly increased skid resistance. PT-1 and PT-2 also have better retention in tensile characteristics after being subjected to thermal ageing, which increases the compounds’ thermal stability. Promisingly, the initial tire tread liner prototype demonstrates a notable rise in the utilization of environmentally friendly raw materials, that comes from natural rubber, silica, processing aid, and EPO, with percentages of 66% (in PT-2 tyre formulation) and 70% (in PT-1 tyre formulation), respectively. This stands in contrast to the control sample, which only utilized 51% of green raw materials. This substantial increase in the incorporation of green materials significantly enhances the tire tread liner's overall sustainability and ecological footprint.