The Evolution of Microstructure under Tensile Stress and the Effect of Temperature on Vitrimer

Vitrimer, which has network structure formed by dynamic covalent bond, is a new polymer material whose structure can be modified by heat and pressure such as thermoplastic polymer, enabling reprocessing and recycling. The structural rearrangement is caused by exchange reaction promoted by catalyst, and the catalyst content affects the reaction rate. The exchange reaction rate accelerated when it is heated and chain become more mobile, resulting in easier structural change. Therefore, temperature and the mechanical properties act as critical variables in determining processing conditions. When tensile stress is applied, the polymer with dynamic bond, such as vitrimer, can show stress relaxation behavior through network rearrangement when stretched at sufficiently slow strain rate.

In this work, tensile stress is applied to vitrimer to observe the chain behavior and evolution of microstructure in various strain rate. Stress relaxation test was conducted to examine the relaxation behavior of polymer chain. Small angle x-ray scattering (SAXS) was used to investigate the microstructure in static state and structure under stretched state. Through this study, it is expected to provide a clue for determining the optimal processing condition.