The polymerization of bisphenol-A epoxy resin mixed with a curing agent (methyltetrahydrophthalic anhydride) was followed from the liquid to the solid state using the positron annihilation lifetime (PAL) technique at several curing temperatures. With the commencement of polymerization, the intensity, I3, of ortho-positronium started to increase, followed by a sharp decrease of its lifetime, T3. When the curing temperature was raised further, 13 increased to a large value, indicating further propagation of the polymer networks. When the polymerization was terminated, T 3 reached the smallest value and 13 reached a large saturation value. PAL is a powerful technique for studying microscopic structural changes and state transitions of polymers.
Посилання на статтю:
Positron annihilation and polymerization of epoxy resins / T. Suzuki*, Y. Oki, M. Numajiri, T. Miura and K. Kondo // Polymer. – 1993. – Vol 34. – P. 1361-1365.