Studies of macromolecular entanglements. I. Melting behavior of swelling polymers with macromolecular entanglements

In this paper the swelling and melting behavior of several polymers, particularly acrylic fibers, is studied by thermomicroscopy and differential scanning calorimetry in detail. It is confirmed that the protrusion peak on the tail part of the DSC thermogram of swelling polymers is closely associated with the macromolecular entanglements. The proposed swelling DSC method is proved to be very effective for studying polymer entanglements. It is also shown that the melting point, whether of paracrystalline region or of entanglement structural unit, can be well fitted to Flory's melting point depression theory.