Sustainable Plasticizer for Butyl Rubber Cured By Phenolic Resin

Butyl rubber (IIR) cured by phenolic resin is widely used to manufacture rubber products exposed to high temperature environments. In this research, carbon black (CB)-filled IIR containing a petroleum-based plasticizer [naphthenic oil (NO)] and bio-based plasticizers [soybean oil (SO) and norbornylized soybean oil (NSO)] cured by the brominated phenolic resin was studied. The NSO was prepared through the reaction of SO and dicyclopentadiene (DCPD) at different ratios. Gel fraction, crosslink density, curing behavior, thermal, mechanical and aging properties of the CB-filled IIR containing different oils were investigated. The addition of SO and NSO increased the thermal stability of the IIR vulcanizates and also decreased the crosslink density compared to that of the IIR/NO vulcanizate. This was found to be due to the reaction between the phenolic resin and the bio-based oils. Reducing the oil level increased the crosslink density of the IIR/SO and IIR/NSO vulcanizates, which in turn increased the modulus and tensile strength. Among various vulcanizates, the IIR/NSO vulcanizates showed the best overall hot air aging resistance. Results showed that NSO could be a good replacement of the petroleum-based plasticizer in IIR cured by phenolic resins.