Cure Reaction and Phase Behavior of Epoxy-Based Polymer Dispersed Liquid Crystals

In an epoxy resin/polymer dispersed liquid crystal (PDLC) system, the effect of PDLC content (0-40 wt％) has been investigated under dynamic and isothermal curing conditions. In the dynamic curing reaction, the reaction rate of epoxy resin decreased as the PDLC content increased. In the isothermal curing reaction, the reaction rate of epoxy resin decreased as the PDLC content increased or as the curing temperature decreased. This was caused by the inhibition effect of PDLC on the curing reaction of epoxy resin. In addition, the distribution and morphology of PDLC in the cured epoxy/PDLC system have been investigated using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Above 30 wt％ PDLC content, the pattern of DSC peak was changed due to the enthalpy obtained during the phase separation. This has been confirmed by measuring the time required for phase separation. From SEM micrographs, the most uniform and smallest size of PDLC in the cured epoxy/PDLC system was obtained at the PDLC content of 30 wt％.

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