Optical properties of electron beam- and UV-cured polypropyleneglycoldiacrylate/liquid crystal E7 systems |
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Authors: | Mohammed Bouchakour Yazid Derouiche Zohra Bouberka Christophe Beyens Lahcène Mechernène Farid Riahi |
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Affiliation: | 1. Unité Matériaux et Transformations – UMET (UMR CNRS N°8207), Batiment C6, Université Lille 1 - Sciences et Technologies, Villeneuve d’Ascq Cedex, France;2. Laboratoire de préparations, modifications et applications des matériaux polymériques multiphasiques, Université Sétif 1, Sétif, Algeria;3. Faculté des Sciences et de la Technologie, Université Ziane Achour de Djelfa, Djelfa, Algeria;4. Laboratoire Physico-Chimie des Matériaux-Catalyse et Environnement (LPCM-CE), Université des Sciences et de la Technologie d’Oran (USTO), Oran, Algeria;5. Laboratoire de Recherche sur les Macromolécules (LRM), Faculté des Sciences, Université Aboubakr Belka?d, Tlemcen, Algeria;6. Laboratoire de préparations, modifications et applications des matériaux polymériques multiphasiques, Université Sétif 1, Sétif, Algeria |
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Abstract: | This contribution focuses on a detailed investigation of the relationship between the method of polymerisation/cross-linking, such as slow and rapid UV radiation, and high voltage accelerated electron beam (EB), and the obtained physical properties including phase diagrams, polymerisation and phase separation kinetics, morphologies and electro-optic responses of polypropyleneglycoldiacrylate (PPGDA) monomers, in the presence of the nematic liquid crystal E7. The longer the spacing between double bonds, the more rapid was the photopolymerisation under both UV systems; however, the reverse was proved under EB. More homogenous and regular morphologies were obtained under EB curing.The electro-optical responses of various polymer dispersed liquid crystals (PDLCs) systems exhibited remarkable differences between the UV-cured samples and those cured by the EB technique. It was found that the threshold and saturation voltages considerably increased in the case of the UV-cured systems. Other results involving the contrast ratio, which is higher for EB-cured systems, confirm their higher quality, although the rapid photopolymerisation UV source was employed, which slightly improved the electro-optical responses. Moreover, EB curing leads to high enough conversions without a photoinitiator, which may act as an impurity that might have a strong impact on the electro-optical performance of the obtained PDLCs. |
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Keywords: | PDLC polypropyleneglycoldiacrylate E7 liquid crystal photopolymerisation electron beam electro-optical response |
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