An anhydride-acid compound for cross-linking epoxy resin systems
P.D. McLean
R.F. Scott
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Modified dicarboxylic acid anhydride compounds have been made which contain free carboxylic acid groups. These compounds cross-link with epoxy resins giving low exotherms, longer working times and produce strong ductile plastics. The modified compound is made by adding water to the liquid dicarboxylic acid anhydride methyl tetrahydrophthalic anhydride with a small amount of catalyst aod heating. The amount of water added is selected to obtain the desired anhydride to acid ratio. Catalysis of the systems is accomplished by either precatalysis of the resin, by additions of a conventional catalyst or by addition of a suitable catalyst dwing the manufacture of the modified dicarboxylic acid anhydride compound. Strengths of 14000-15000 psi with elongations of 7·9% have been obtained using a cure schedule of 100°C for six hours and 160°C for eight hours. When stoichiometrie quantities of phthalic anhydride were included in the composition, strengths up to 17000 psi have been obtained. The use of the anhydride-acid compound results in generally lower heat deflection temperatures than nadic methyl anhydride. Parts have been made using DG EBA, Novolac or alicyclic epoxy resin systems, by filament winding, wet lay up and preimpregnation, each using vacuum and pressure curing technique.