Effect of solvent exposure on the properties of hydroxy‐terminated polybutadiene‐based polyurethanes

Abstract

Hydroxy-terminated polybutadiene-based prepolyurethanes and diamine chain extended polyurethane-ureas were prepared and treated with various organic solvents in the moisture-cured state in order to modify their ultimate strength. FTIR studies with solvent-treated polyurethanes and polyurethane-ureas confirmed that organic solvents penetrated inside the polyurethane hard segments and affected hydrogen bonding. The polar and non-polar solvents showed different abilities to penetrate into polyurethane hard segments. Solvent treatment after moisture curing increased the tensile strength of these polyurethanes and polyurethane-ureas with respect to control samples. The stress-strain behaviour of solvent-treated polyurethane follows the constrained junction model. The change in hard segment crystallinity on solvent treatment has been explained by wide-angle X-ray diffraction study. The better orientation in polybutadiene soft segments evidenced from SEM (scanning electron microscopy) pictures is believed to be the main reason behind the improved tensile properties of solvent-treated polyurethane samples. The effect of solvent treatment, as well as stretching, on the diffusion coefficient of hexane in polyurethanes was investigated.

Simultaneous Improvement of Tensile Strength and Elongation: An Unprecedented Observation in the Case of Hydroxyl Terminated Polybutadiene Polyurethanes

“…A vast amount of work has been reported in the literature on the HTPB based PUs. A majority of these reports studied structure–property relationship of this segmented PU. − A considerable amount of effort has been made toward the studies of thermal stability, effect of aging, susceptibility toward oxygen, and especially the mechanical stability. − Several types of diisocyanate structures have been used to elucidate the structure–property phenomenon of the PUs . A careful analysis of the literature reports brings a general observation that most of the researchers made efforts to improve the tensile properties of HTPB based PUs.…”

Preparation of laminated safety glass based on high strength polyurethane film by solution annealing

“…Solvent engineering is an important impact factor for functional polymer materials, [28][29][30][31] the higher strength of polymers can be achieved depending on their molecular motion after penetrated with solvents, [32][33][34][35] which can disrupt the balance between polymer chains by supramolecular self-assembly or multiple hydrogen bonds modulation. 36,37 Inspired by this, we designed to swell the TPU material by solvent, and it can recombine the weak bonds of the polymer chain in the process of volatilization.…”

Tuning Interaction Parameters of Thermoplastic Polyurethanes in a Binary Solvent To Achieve Precise Control over Microphase Separation

“…Among the parameters related to reaction conditions and processing protocols, the selection of the solvent is critical for the preparation of TPUs ,, to be used for further investigation of their structure–property relationships in both solution and solid states. However, the number of studies focusing on this parameter is highly limited in the extensive base of TPU literature. ,− Moreover, introduction of dual solvents with different affinities to the SS and HS parts of TPUs brings about interesting new features to the behavior of the copolymers that are not obtainable by a single solvent . In fact, tuning structure–property behavior of complex macromolecules, such as copolymers, using dual solvent systems is a well-established approach encountered in the polymer physics literature. − …”