Eco-friendly rubber compounds: Utilizing animal lard as a plasticizer oil

Melt-mixing technique was used to compound eco-friendly plasticizer, pork fat oil (PF) and natural rubber (NR)-carbon black (CB) and studied systematically. The results obtained for the PF-compounds (PFC) were compared to petroleum oil compounds (POC) and Shea-butter oil compounds (SBC). While some properties of the PFC were similar and favored those of the POC and SBC, the PFC generally demonstrated superior physico-mechanical properties. For instance, the optimum cure time (T₉₀) of PF5 and PF40 reduced to about 225 and 276% when compared to POC5 and POC40 and 150 and 183% relative to SBC5 and SBC40, respectively. The bound rubber content (BRC %) (filler-matrix interactions) of PF5 was over 15% and 5% greater than POC5 and SBC5, respectively. Also, the PF5 outperformed POC5 by 12% in crosslinking density and by 7% in rebound resilience (%). The PF5 and PF40 further showed improvements in fatigue life cycle, exceeding POC5 and POC40 by 40% and 75%, respectively. These enhancements were attributed to the effective distribution of CB particles facilitated by compatible PF within the NR matrix. Therefore, PF has been demonstrated to be an environmentally friendly, cost-effective, and compatible plasticizer for rubber compounding compared to POC and vegetable oil, predominantly as an activator for lowering production time. Highlights: Natural rubber was compounded with carbon black, with pork fat as a plasticizer. The pork fat compounds (PFC) showed superior physico-mechanical properties. The properties were better than aromatic and vegetable oil (VO) compounds. The fat oil was demonstrated to be a suitable and eco-friendly plasticizer. The fat can substitute carcinogenic oils and prevent using VO as a plasticizer.