Thermal transitions studied by Iso-strain Force-Temperature Test (IFTT)

A new thermal-mechanical test method called Iso-strain Force-Temperature Test (IFTT) is proposed in this paper to study the thermal behavior of polymeric materials. It is shown experimentally that this test method gives high sensitivity in detecting thermal transitions, including sub-Tg transitions or relaxations, glass transition and melting. This method was utilized to investigate thermal properties of different forms of polymeric materials with inherent anisotropy, such as fibers and films. A variety of polymeric materials were examined, which included fibers of Kevlar® and Spectra®, and films of Teflon®, bisphenol APC and PET. This method shed new light on the thermal transitions in PPTA fiber.