Properties of polyurethane elastomers and composites by thermal analysis

Polyurethane elastomers based on castor oil or polybutadiene liquid hidroxyl (PBLH), as well as polyurethane composites reinforced with coir or sisal fibers at different proportions: 5, 10 and 20% w/w were prepared. The thermal behavior of the samples was analyzed by thermogravimetry (TG/DTG). TG/DTG curves showed two decomposition stages, except samples from castor oil with three decomposition stages (Tonset 257°C). The PU from PBLH presented a principal degradation at around 400°C, but with 15% weight loss at 250°C and the composites exhibited first decomposition stage at around 290°C. MDSC thermal profiles for PBLH PU presented one transition, occurring at the glass transition temperature (Tg) 73.8°C, two transitions in castor oil PU Tg: −1.6 and 62.7°C, and three transitions for composites from sisal Tg: −52.9°C, 66.7 and 122°C. These transitions suggest soft and hard segments.