Studies of the Cross-linking and Glass Transition of Fatty Acid-Modified Alkyd Resins

Abstract

Abstract a) The degree of cross-linking observed in films of fatty acid modified alkyd resins increases with the content of unsaturated acids. Moreover, cross-linking is not so effective in raising the Tg as the benzene ring, which has a larger cohesive energy. b) Both the Tg and the degree of cross-linking increase with the increase in the molecular weight of the prepolymer. c) The excess of glycerol employed in fatty acid-modified alkyd resin is effective in raising the Tg and encouraging the progress of the cross-linking. d) Generally, the cross-linking is not soon completed; as time elapses, the Tg rises, and the cross-linking progresses. No change in the Gh with the elevation of the Tg (baked film with the addition of a drier) is considered to be caused by the formation of polar groups by air-oxidation. e) In the early period of drying, a sub-glass transition caused by the unrestrained chain of the acyl groups is observed.