Upcycling rendered chicken oil: Novel carbon black as a potential filler for silicone rubber

The generation and accumulation of slaughter waste from poultry industries pose a serious environmental threat, especially to ecologically fragile regions like the Western Ghats. Converting this waste into a raw material for other industries offers a sustainable solution, fostering business collaborations, research innovations and global industrial integrations. The present research focuses on converting rendered chicken oil into a novel grade of carbon black through a three-stage thermolytic carbonization process. The performance of the prepared carbon black as a filler in silicone rubber has been evaluated against industrial-grade carbon blacks, specifically intermediate super abrasion furnace black (ISAF) and super abrasion furnace black (SAF). The synthesized carbon black has 83.44% carbon content with sharp and characteristic X-ray diffraction peaks at 2ϴ values of 25.36° and 43.56°. Under the shearing action of the mixing mill, the most frequent particle size reduced from 72 nm to 35 nm, indicating effective fragmentation within the silicone rubber matrix. Rheometric analysis revealed that the cure reaction initiated within 2 minutes for most samples and is accelerated by increasing temperatures. The addition of 5 phr (parts per hundred rubber) of the prepared carbon black slightly increased induction time but maintained satisfactory scorch safety. Furthermore, rheometric first-order cure reaction rate constants increased with temperature and the presence of carbon black. Mechanical property evaluation demonstrated that incorporating 5 phr of the prepared carbon black resulted in a tensile strength of 3.57 N/mm 2 and a tear strength of 16.44 N/mm. The addition of 5 phr of prepared carbon black filler enhanced tensile strength by 11% and tear strength by 13% in silicone rubber vulcanizates. These improvements were corroborated by scanning electron microscopic fractography and cross-link density measurements from equilibrium swelling studies.