Synthesis and performance of multifunctional lubricant additives based on renewable tung oil

Purpose This study aims to design and synthesize a novel vegetable oil-based lubricant additive – poly(tung oil-styrene) (PTST) and to systematically evaluate its comprehensive performance as a pour point depressant, viscosity index improver and anti-wear additive. Design/methodology/approach The polymerization conditions were optimized by a single-factor experiment method. The copolymer was characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy and gel permeation chromatography. Additionally, its pour point depression performance, viscosity-temperature performance and anti-wear performance were evaluated in accordance with the Chinese standard methods GB/T 3535-2006, GB/T 265-1988 and NB/SH/T 0189-2017, respectively. Findings Compared with poly(tung oil-methyl methacrylate) with a short straight-chain structure, PTST with a benzene ring structure exhibited superior thermal stability and pour point depression performance, but inferior viscosity-temperature performance. Meanwhile, the two copolymers exhibited similar anti-wear performance. Originality/value This work presents a renewable, multifunctional lubricant additive that simultaneously enhances low-temperature flow, viscosity-temperature behavior and anti-wear performance. PTST exhibits strong potential as an eco-friendly alternative to replace traditional petroleum-based additives.