Synthesis and properties of peroxy derivatives of epoxy resins based on bisphenol A. 1. Effects of the presence of inorganic bases

Oligomers containing peroxy groups have been synthesized from epoxies and aliphatic and aromatic hydroperoxides. The dependence of reaction rates upon ratios of starting materials, the presence of an inorganic base as a catalyst, nature of solvent, quantity of water, and temperature have been investigated. The hydroperoxide + epoxy reactions proceed very slowly in the presence of NaOH but at satisfactory rates In the presence of KOH. The reactions do not proceed in acetone, methylethylketone, dioxane, or toluene, but do proceed in secondary and tertiary alcohol media. We have studied in particular the reaction between tert-butyl-hydroperoxide (tBHPO), diglycidyl ether of diphenylpropane and an epoxy resin based on Bisphenol A and epichlorohydrin. Structures of the products were confirmed by LR and H-1-NMR spectroscopy. Mechanisms of reactions have been defined and an empirical equation that describes kinetics of the reaction between tBHPO and the epoxy has been developed. The peroxy oligomers so obtained were used to create networks based on a polyesteric resin. Going from 10 wt% of the peroxy oligomer to 25% increases significantly the rate of gelation as well as the final gel weight fraction. However, a further increase of the peroxy oligomer concentration to 50% affects only slightly the gelation kinetics and the plateau gel fraction.