Fecha de publicación: 22/11/2024 Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE ABSTRACT
Despite the versatility and extensive applications of hydroxyl-terminated polybutadiene (HTPB)-based thermoset polyurethanes (PUs), research on tailoring their performance through hard-segment modulation is limited. In this study, the impact of hard segment (HS) content modulation (20%–50%) on the properties of two series of HTPB-based thermoset PU elastomers at R (NCO/OH) 1.5 and 1.6 was investigated. The effect of increasing the HS content on processability, structural confirmation, physico-mechanical properties, thermal properties, and crystallinity was evaluated through rheological analysis, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and x-ray diffraction (XRD). Both series showed 19% and 23% increases in the hydrogen bonding index (HBI) with HS modulation. The pot life at R = 1.5 decreased from 373 to 284 min and at R = 1.6, from 265 to 210 min. The crosslink density, glass transition temperature, and thermal stability increased for both series with higher HS content. At R = 1.5, the tensile strength increased by 105% and the maximum elongation increased to 40% HS before decreasing. At R = 1.6, the tensile strength increased by 81%, and the maximum elongation increased to 30% HS before decreasing. These findings clarify how hard-segment modulation affects thermosetting PU structure, processing, and performance.