Improving performance of TPU by controlled crosslinking of soft segments

Thermoplastic polyurethanes (TPUs) are a family of thermoplastic elastomers with great properties such as high elongation and excellent chemical and abrasion resistance, which are processable by conventional melting methods. Nevertheless, TPUs lose mechanical properties and thermal stability at higher temperatures. In this work, we designed and synthesized a new TPU with limited crosslinking of the soft segments in order to improve its performance at high temperatures while preserving processability. Additionally, the new TPU maintains its transparency. With the incorporation of 10% trifunctional polyol, the Tg was increased by 7°C, the storage modulus at room temperature (25°C) was improved by 412 MPa (136%), the rubbery plateau was extended by 32°C and the thermal stability was enhanced by 4°C at T5. Moreover, the TPU with controlled crosslinking of the soft segments shows exceptional creep behavior both at room temperature and at 150°C, where the creep rate decreased by 80%. The new TPU shows limited decrease in tensile properties and can be processed by conventional thermoplastic processing techniques. Highlights Design and synthesis of a new TPU with limited crosslinking of the soft segments. Incorporation of the crosslinks into the soft segments preserves system processability. Enhanced mechanical and thermal properties while preserving system transparency. High temperature application window extended by 32°C. Creep rate at 150°C lowered by 80%. Incorporating a small amount of trifunctional polyol into the soft segment of a TPU can significantly enhance its high temperature mechanical performance and thermal stability while preserving processabilty.