Effect of Exo- and Endothermic Blowing and Wetting Agents on Morphology, Density and Hardness of Thermoplastic Polyurethanes Foams

Thermoplastic polyurethane (TPU) combines the property characteristics of high quality polyurethane elastomers with the processing efficiency of thermoplastics. Foaming of TPU material inputs for existing applications also leads to improved material properties for new applications. The mixture of exo- and endothermic type of blowing agents is investigated for production of TPU foam technique. Azodicarbonamide (ADC) and sodium bicarbonate are used as exothermic and endothermic blowing agents, respectively. The thermal decomposition and foaming behaviors of blowing agent ADC with kicker and the combination of exo- and endothermic blowing agents are investigated systematically. The ingredients of the mixture of exothermic blowing agent are mixed to suit the processing of TPU. Injection molding of TPU exo- and endothermic blowing agents has been carried out successfully and the morphology is studied using scanning electron microscope. In addition, the effect of wetting agents on the decomposition temperature and processing is also studied. The effectiveness of the use of exo- and endothermic blowing agents is established with the uniform and consistent cell structure with a density reduction of 40% in the foam.