Study of the γ‐alumina polymerization of furfuryl alcohol

Abstract The γ‐alumina polymerization of furfuryl alcohol produces a polymer differing in structure from that obtained by polymerization with acid catalysts. In order to gain a better understanding of the basic chemistry of this method of polymerization furfuryl alcohol, studies were done, both with γ‐alumina‐polymerized and acid‐polymerized furfuryl alcohol resins, concerning both the chemical nature of the resin constituents, and the manner in which these constituents affect resin molecular size distribution as measured by gel permeation chromatography. Because of numerous side reactions, the γ‐alumina polymerization of furfuryl alcohol was found to result in the early elimination of many of the molecules containing functional groups necessary to the sustenance of polymerization. As a consequence even at advanced degrees of polymerization there remain relatively large amounts of low molecular weight components that have not further polymerized. At the higher degrees of polymerization, the high molecular weight end of the resin molecular size distribution was observed to be significantly enhanced over that of the acid‐polymerized resins. The latter behavior is attributed to the occurrence of crosslinking reactions made possible by the higher temperature required for polymerization with γ‐alumina. It is further concluded that the curing processes of γ‐alumina‐polymerized furfuryl alcohol resins proceed by a mechanism unlike that of the acid‐polymerized resins.