Infrared studies of the reversible stress‐induced crystal‐crystal phase transition of poly(tetramethylene terephthalate)

The reversible stress‐induced crystal‐crystal phase transition of poly(tetramethylene terephthalate) (PTMT) has been studied using infrared spectroscopy. Two spectral regions were used to study this transition: the 900–1000 cm−1 methylene rocking region and the 1300–1550 cm−1 methylene bending region. The bands at 917 and 1456 cm−1 are assigned to the ∝ phase. The bands at 935 and 1388 cm−1 have components from the α phase and the β phase. Dynamic stretching experiments performed above and below the glass‐transition temperature indicated different mechanisms of the phase transition.