TSC study and electro-optical properties of epoxy/acrylic polymer-dispersed liquid-crystal film in DICY thermal cure

We report on the structures and electro-optical properties of epoxy/acrylic polymer-dispersed liquid-crystal (PDLC) films. A thermal stimulated curren t (TSC) analysis was used to investigate the physical structures of PDLC. I n the TSC spectrum of PDLC, three relaxation peaks were observed: the glass transition of the liquid crystal, the glass transition of the polymer matr ix, and the rho transition. The rho transition represents the discharge beh avior of space charges, and its intensity increased as the curing time and content of the curing agent dicyandiamide (DICY) increased. The pre-W-cured films with different DICY contents were thermally cured at 130 degreesC fo r various periods. The electro-optical properties of PDLC, such as the cont rast ratio and switching voltage, increased as the curing time of DICY, the content of DICY, or both increased. As the ambient temperature increased f rom 10 to 40 degreesC, the contrast ratio and switching voltage of PDLC gra dually decreased. (C) 2001 John Wiley & Sons, Inc.