Effect of expandable graphite on flame retardant, thermal and mechanical properties of thermoplastic polyurethane composites filled with huntite&hydromagnesite mineral

The effect of expandable graphite (EG) was studied on the flame retardant, thermal and mechanical properties of thermoplastic polyurethane (TPU) containing huntite&hydromagnesite (HH). According to the flammability tests results, the synergistic interaction was observed between HH and EG. The maximum limiting oxygen index (LOI) value was observed at a ratio of 1:1 (HH:EG) and the highest vertical burning test (UL-94) rating of V0 was observed at a ratios of 4:1, 3:2 and 1:1. The synergistic interaction between EG and HH was also deduced at low percentage of EG (10%) by the help of the mass loss calorimeter test results. Mechanical test observations revealed that the inclusion of HH reduced the tensile strength and elongation at break values and increased the elastic modulus and glass transition temperature of pristine TPU. The addition of EG was further improved the elastic modulus of composites as the loaded amount of EG increased.