Study on thermodynamic properties of polyurethane fibers under small strain

In thiswork, dynamic thermodynamic analyzer (DMA) was used to determine the stress-temperature relationship of polyurethane fibers to research the thermodynamic properties under small strains. The results show that the stress of polyurethane fibers increases with the increase of temperature. The study of the energy conversion during the heating processof polyurethane fibers demonstrates that the entropy change decreases with the increase of the strain while the enthalpy change has the contrary tendency. The entropy change is the key reason for the stress of polyurethane fibers. (paper)