Thermosetting resins cause residual stress due to changes in curing volume, which is the main cause of premature failure of thermoset materials. The residual stress is removed and the desired cure volume shrinkage is equal to zero. Tricyclic oxazolidine-lactam-lactones (TOLL) has three cyclic structures, in which one ring is subjected to ring opening polymerization during thermosetting to form poly(ester-imide). The polymerization reaction can be triggered by the scorpion or the scorpion scorpion, so the TOLL has the condition of becoming an epoxy resin curing agent. This bismuth curing agent has been proven to have application value, and even in the absence of other catalysis, the epoxy resin is thermally cured by the addition of TOLL. The addition of the scorpion and the scorpion scorpion catalyst also confirmed the effect of accelerated curing. The volume shrinkage when the epoxy resin is cured is also reduced by the ring-opening polymerization reaction of TOLL, and the degree of shrinkage is determined by the content of TOLL, and the rate of change of the volume of zero solidification can be obtained under the use amount of the appropriate amount of TOLL. The epoxy resin which is substantially cured by TOLL has high toughness, high rigidity and bending strength.

Epoxy resin Hardener