Studies on chain extension of a novel bio-based engineering elastomer using 4,4-diphenyl methane diisocyanate as a chain extender

A novel hydroxyl-terminated bio-based engineering elastomer (BEE) was synthesized from four bio-based monomers by adding excess diol. Then the BEE was chain extended in Haake torque rheometer with 4,4-diphenyl methane diisocyanate (MDI) as chain extender. The molar ratio of NCO/OH, reaction temperature and reaction time of the chain-extension reaction were studied, and the optimum condition was determined by the gel permeation chromatography (GPC), soxhlet extraction, and fourier transform infrared spectroscopy (FTIR) results. After chain extension, (i) the number-average molecular weight of BEE became about 3.5 times of the original BEE, (ii) the thermal stability was improved and the crystallization rate was lower, (iii) and the mechanical properties were significantly improved with nano-SiO₂ as reinforcing filler. The chain-extended BEE would have potential wide applications in engineering field.