Influence of hard segment on thermal degradation of thermoplastic segmented polyurethane for textile coating application

An attempt has been made to investigate the thermal degradation of thermoplastic segmented polyurethane (TSPU) as a function of hard segment (HS) content. TSPU, and its corresponding hard segment and soft segment, has been studied in air and nitrogen. Comparing the results of solid conversion of polyurethane in different conditions (air and nitrogen), significant differences were observed. Derivative thermogrametry (DTG) analysis revealed that the degradation was a three-step weight loss process in air and two steps in nitrogen. Multiphase degradation occurs in air due to the oxidation reaction of polymer. Therefore, an extra peak appeared in air (in the temperature range between 509 and 583 degrees C). Degradation temperature of 10% (T-10) and the temperature of half-decomposition (T-d,T-1/2) increased with decreasing hard segment content in the TSPU. Thermal stability of polyurethanes decreased after introduction of hydrophilic segment (PEG-200) in the polymer backbone due to the increasing oxygen molecules. The surfaces of the original films, detected by scanning electron microscopy (SEM), were smooth. However, stress cracking was observed for heat-treated deformed TSPU films with higher hard segment content.