Preparation and properties of MDI-based polyester polyurethane elastomer

Polyurethane has been usually used as protective coating on structures, with an important mechanism being the impact-induced transition of the rubber to the glassy state. The better the mechanical property, the greater the mechanical loss, the wider the T_g range, and the T_g is more close to, but less than, the operating temperature, the better the protective coating. Here, the pre-polymer method is adopted to synthesize MDI-based polyester polyurethane (TPU) which has different hard segment contents. The infuence of the hard segment content on the relevant performance of TPU is investigated. With the increase of the hard segment content, the tensile strength, T_g of the soft segment phase and the mechanical loss increase, while the viscosity of reaction solution increases rapidly, the elongation at break declines sharply, and the range of the T_g becomes narrower and narrower. Therefore, in order to obtain excellent protective coating, the hard segment content should not be too high. Testing proves 16.18% hard segment content to be most effective.