Abstract
The episulfide resins with fluorene backbone moiety were synthesized by replacing the oxygen atoms on the oxirane ring of bisphenoxy ethanol fluorene epoxy resin with sulfur atoms using thiourea compound. In the substitution reaction, the conversion of oxirane ring to thiirane ring could be controlled by changing the reaction time. The episulfide resins obtained were cured with 1,3-Bis(aminomethyl)cyclohexane. Thus, the transparent cured episulfide resins which have high refractive index (nd > 1.61) and relatively low birefringence were obtained. The episulfide resins in which the contents of thiirane rings are 70 and 90% formed phase separation in their curing process. These phase separated resins also have high transparency in the visible right region. In addition, these resins showed high tensile fracture energy caused by the stress distribution which arises from the phase separation structure.
