Relaxations in the transition region of crosslinked polyesters. I. The β relaxation

The glass transition region of styrene‐crosslinked poly(1,2‐propylene phthalate fumarate) was studied using a torsion pendulum. The region was composed of two separate relaxations. The major relaxation was the glass transition of the whole network, while the minor relaxation, at a lower temperature, was ascribed to the polyester segments between the crosslinks. A comparison was made between these relaxations and these observed in related polyester networks.