A Room-Temperature High-Damping and High-Strength Polyurethane Elastomer with Pendant Chains

Currently, the glass transition temperature ( T _g ) of traditional damping polyurethane elastomers (PUEs) remains far below room temperature. Polyurethane elastomers synthesized from castor oil-based polyol exhibit favorable damping performance at elevated temperatures along with excellent mechanical properties. In this work, an isocyanate-terminated castor oil-based polyurethane prepolymer was synthesized using castor oil-modified polyol (DPH) and isophorone diisocyanate (IPDI). The monohydroxy groups in polypropylene glycol monobutyl ether (BPPG) were end-capped with IPDI to form pendant chain prepolymers (BPPG-PU), which were subsequently grafted onto the castor oil-based polyurethane prepolymer via a trimethylolpropane (TMP) crosslinker, producing room-temperature high-damping and high-elasticity polyether-type polyurethane elastomers (BPUE). The dynamic mechanical properties, thermal stability, microstructure, and mechanical performance of BPUE were comprehensively investigated. Results demonstrated that BPUE-0% (without pendant chains) exhibited outstanding performance: a T _g of 58.9 °C, a maximum damping factor (Tan δ _max ) of 1.17, and a tensile strength of 11.50 MPa. With the incorporation of pendant chains, the effective damping temperature range broadened, and T _g shifted toward room temperature. While tensile strength decreased, elongation at break initially increased and then declined with higher pendant chain content. Among BPUEs with varying chain lengths, longer pendant chains significantly enhanced hydrogen bonding reinforcement. Overall, BPUE15-30% displayed optimal performance, achieving a T _g near room temperature (29.3 °C), an expanded damping temperature range of 63.9 °C, a damping factor of 0.91, and a maximum elongation at break of 407.29% while retaining a tensile strength of 2.94 MPa. Additionally, all BPUEs exhibited high transparency, with transmittance exceeding 80%.