Thermal and mechanical properties of thermoplastic urethanes made from crystalline and amorphous azelate polyols

Abstract

ABSTRACT Polyester polyols from renewable resources have gained significant interest in the field of polyurethane chemistry. Two sets of segmented TPUs were prepared from crystalline and amorphous azelate polyols, 4,4′‐methylenebis(phenyl isocyanate), and 1,4‐butanediol as a chain extender at a mole ratio of 1:2:1, respectively. Bio‐1,3‐propanediol (1,3‐PDO) and 1,5‐pentanediol (PTDO) were used to prepare crystalline azelate polyols, while 1,2‐propanediol (1,2‐PDO) and 2,2′‐dimethyl‐1,3‐propanediol (NPG) were used to prepare amorphous azelate polyols. All TPUs displayed clear glass transition temperatures ( T g s) in between −36 and − 24 °C, associated with azelate polyols soft segments, which are decreasing with increasing diols chain lengths in azelate polyols. TPUs based on crystalline azelate polyols exhibited higher mechanical properties and better heat resistance in comparison to their counter parts. Besides, TPU based on 1,3‐PDO azelate showed lower percentage of hysteresis indicating lower heat build‐up. This is essentially good for TPUs that are to be used in dynamic applications such as rollers and wheels. Hence, the study on structure–property correlation of the crystalline and amorphous azelate polyols and their effect on TPUs properties suggest that crystalline azelate polyols are suitable for dynamic application of TPU, and amorphous azelate polyols are suitable for coatings and adhesives applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47890.