Polymer Dispersed Liquid Crystal materials were elaborated by in situ polymerization induced phase separation under ultraviolet (UV) radiation. Binary model systems composed of a diacrylate monomer and a liquid crystal (LC), 4-cyano-4'-n-pentyl-biphenyl (5CB), were used as starting materials in the process of polymerization/crosslinking. The optical transmission of the monomer/LC films was monitored as function of time covering the period of exposure to UV-light and the following relaxation processes of the irradiated samples. The off-state transmission shows several characteristic processes, a short time relaxation process which decays within seconds, an unexpected intermediate period where transmission was found to enhance, followed by a long lasting relaxation process which takes tens of minutes to decay completely. A discussion of these processes in terms of the kinetics of phase separation is presented.