ABSTRACT:The photopolymerization of methyl methacrylate (MMA) through the use of a novel disulphide, 2,2Ј-dithiodiethanol (DDE), was studied. This photoinitiator is of special interest because of its possible use in the synthesis of polyurethane macrophotoinitiator. The photopolymerization was carried out in the Heber multilamp photochemical reactor (COMPACT-LP-MP88) at 254 nm. The effects of reaction conditions on the polymerization of MMA were studied. It was observed that the percentage conversion and molecular weight increased with the increases of monomer concentration and reaction time. However, for the initiator to monomer molar ratio, there was a critical molar ratio for maximum conversion. The results suggested the living radical nature of the photoinitiator, which was further investigated by the preparation of block copolymer with acrylonitrile.

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This work presents outage analysis of a hybrid communication system, where radio frequency (RF) and free space optical (FSO) communication links transmit in parallel to the then cascaded underwater wireless optical communication (UWOC) link forming a RF/FSO-UWOC cooperative system. Optical wireless communication (OWC) is being used as a viable communication technology by researchers due to its advantages such as fast speed, cost effectiveness, and highly secure transmission. The proposed architecture connects the terrestrial and the underwater regions to form an end-to-end cooperative system. This hybrid RF/FSO back-haul link makes the system more reliable as the optical link is highly susceptible to weather conditions. The channel models considered are Nakagami-m distributed fading, Double Generalized Gamma (DGG) distributed atmospheric turbulence along with Rayleigh distributed misalignment losses and mixture of Exponential Generalized Gamma (EGG) distributed oceanic turbulence for RF, FSO, and UWOC links, respectively. Results show that outage performance is severely affected due to RF fading, DGG distributed irradiance, air bubble concentration, temperature gradient, and saltiness of water source