Thermoplastic polyurethane foamed under microwave irradiation

Microwave heating has a number of advantages over the conventional method. However, most thermoplastics are relatively transparent for microwave irradiation. In the case of polyurethanes, these materials absorb microwaves to a sufficient extent to be heated. This effect can be enhanced by the use of fillers such as carbon black. In this paper, the ability of thermoplastic polyurethane and its composite with carbon black to be heated by microwave irradiation and to be foamed using chemical blowing agents are discussed. The temperature changes in different parts of samples as the heating effect under microwave irradiation with 500 W power were analyzed. Selected porous products were obtained under microwave irradiation using azodicarbonamide as a chemical blowing agent. The influence of foaming conditions on cell structure, apparent density and mechanical properties of porous products was estimated.