Application of Different Vegetable Oils as Processing Aids in Industrial Rubber Composites: A Sustainable Approach

Abstract

Rubber composites based on renewable vegetable oils are being increasingly developed, as these materials significantly reduce the use of petroleum-based carcinogenic oils as plasticizers in rubber products. Apart from renewability, vegetable oils have some major advantages, such as easy availability, biodegradability, and environmentally friendly nature. Until now, vegetable oils, such as palm oil, soybean oil, and linseed oil, have been successfully used as processing oils to replace petroleum-based oils in engineered rubber composites. So far, the concept of a vegetable-oil-based plasticizer has been applied to rubber composites containing different industrially important fillers, like carbon black, silica, calcium carbonate, and expandable graphite. In the near future, the trend of utilizing vegetable-oil-based plasticizers may bring considerable advancements in the performance of filled rubber composites in an environmentally acceptable and sustainable manner.

Figure 1

Stress–strain curves of EPDM composites based on PMO and PO. Reprinted with permission from Wang, Z.; Peng, Y.; Zhang, L.; Zhao, Y.; Vyzhimov, R.; Tan, T.; Fong, H. Investigation of palm oil as green plasticizer on the processing and mechanical properties of ethylene propylene diene monomer rubber. Ind. Eng. Chem. Res.2016, 55, 2784–2789. Copyright 2016 American Chemical Society.

Figure 2

Tensile strength values of SBR composites plasticized with castor oil, jatropha oil, and aromatic oil. Adapted with permission from Pechurai, W.; Chiangta, W.; Tharuen, P. Effect of vegetable oils as processing aids in SBR compounds. Macromol. Symp.2015, 354, 191–196. Copyright 2015 John Wiley and Sons.

Figure 3

Possible chemical interaction between ester groups of NO or MO and silanol groups of silica. Reprinted with permission from Boonrasri, S.; Sae-Oui, P.; Reungsang, A.; Rachtanapun, P. New Vegetable Oils with Different Fatty Acids on Natural Rubber Composite Properties. Polymers2021, 13, 1108. Copyright 2021, MDPI.

Figure 4

Cross-link density values of NR/EG composites plasticized with linseed oil and naphthenic oil. Adapted with permission from Fernandez, S. S.; Kunchandy, S.; Ghosh, S. Linseed oil plasticizer based natural rubber/expandable graphite vulcanizates: Synthesis and characterizations. J. Polym. Environ.2015, 23, 526–533. Copyright 2015 Springer Nature.