A study of the degradation of ester-modified epoxy resins obtained by cationic copolymerization of DGEBA with γ-lactones initiated by rare earth triflates

The thermal degradation of new thermosetting materials prepared by cationic copolymerization of mixtures with different proportions of diglycidylether of bisphenol A (DGEBA) with γ-valerolactone (γ-VL) or α-methyl-γ-butyrolactone (γ-MBL) initiated by scandium, ytterbium or lanthanum triflate and a complex of boron trifluoride was investigated. To study the thermal degradation thermogravimetry (TGA) was used. The materials are more degradable than conventional epoxy resins due to the presence of ester groups in the polymer chain, which are broken at the beginning of degradation. The degradability increased with the proportion of linear ester groups and the Lewis acidity of the initiator used in the polymerization and when the proportion of lactone in the initial mixture increased. The kinetic parameters of the degradation were calculated from TGA data by applying isoconversional procedures.