Vitrimer-like Material Prepared from a Bio-renewable Elastomer with a Dimeric Fatty Acid

Abstract The development of cross-linked epoxidized natural rubber (ENR) that is recyclable, repairable and weldable is presented in this paper. Dimer fatty acid (DFA) was used as cross-linker in ENR50 to generate β-hydroxy ester linkages through epoxide ring-opening reaction between carboxylic groups in DFA and epoxide groups in ENR. Meanwhile, a transesterification catalyst (Zinc catalyst) provided a dynamic covalent network in the cross-linked ENR, which is a vitrimer-like elastomer. The mechanical properties and cross-link density of this vitrimer-like rubber could be tailored by changing the concentration of DFA. Using DFA at approximately 1.5 mmol COOH (~1.23 phr) in ENR50 offered good tensile strength and elongation at break. Stress relaxation showed that the reaction rate of bond exchange in DFA-cured ENR could be significantly accelerated by increasing temperature, suggesting malleable flow of these vitrimers. Moreover, the prepared vitrimer-like elastomer showed repairable, weldable, recyclable and reprocessable characteristics. This technological approach is significant in providing a covalent adaptive network in vulcanized rubber, which has great potential for further development of environmentally friendly rubber vulcanizates.