Synthesis and properties of polyurethane elastomers based on renewable castor oil polyols

ABSTRACT In this contribution, castor oil polyols with functionality of f = 2.7 and f = 2 are used as soft segments (SS) for synthesizing polyurethane elastomers (PUEs) without addition of petroleum‐based polyol. The effect of molar ratio of castor oil polyols on structure and properties of PUEs has been investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, X‐ray diffraction, tensile, swelling, and water absorption tests. The results reveal that hydrogen bonding mainly exists in hard segments (HSs) and weakens with decreasing the molar percentage of castor oil polyol ( f = 2.7) in SS. T g of SS decreases while T g of HS remains constant as molar percentage of castor oil polyol ( f = 2.7) decreased. The initial degradation temperatures ( T 5% ) are above 300 °C and independent of the molar ratio of castor oil polyols. However, the temperature at 50% weight loss ( T 50% ) decreases significantly as molar percentage of castor oil polyol ( f = 2.7) decreased. Moreover, PUEs exhibit very low water absorption rate, <1%, after immersing in water for 140 h at room temperature. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47309.