Systematic evaluation of a sustainable plasticizer derived from coconut shell bio-waste in a reinforced styrene butadiene copolymer system.

The utilization of copiously available bio-waste significantly contributes to sustainable development and solid waste management. In the present study, the pyrolytic extract of coconut shell bio-waste is evaluated as a plasticizer in carbon black filled styrene butadiene rubber (SBR) compared with conventionally used aromatic oil (AO) at varied levels of 5, 10, 20, 30, and 40 phr. The pyrolysis of the coconut shell was accomplished in an inert environment using a tube furnace. The coconut shell oil (CSO) was evidenced to take part in the curing reaction increasing mechanical properties. Tensile strength increased to ~36% and tear strength by ~30%, which is attributed to the reactivity of CSO with sulfur. ¹H NMR studies and the lower percentage of solvent extract for CSO filled vulcanizates confirmed the chemical interaction of CSO with sulfur and subsequent bonding to the rubber chain. The De Mattia flexing resistance showed a multi-fold improvement of 657% for CSO filled vulcanizates pertaining to enhanced internal lubrication and coherent movement of chemically bonded plasticizer with rubber chains under dynamic conditions. Thermogravimetric analysis indicated a shift in the onset of volatilization temperature from 250 °C to 370 °C upon replacement of AO with CSO showing enhanced thermal stability. Glass transition temperature was decreased by 5 °C at 40 phr plasticizer loading for CSO filled vulcanizates indicated better plasticization. CSO is a potential cost-effective, non–toxic, and sustainable alternative to the conventionally used petroleum-based aromatic oil as the plasticizer. [ABSTRACT FROM AUTHOR]