Optical Study Of Polymer Dispersed Mixed Liquid Crystals
Recently, Liquid Crystal (LC) dispersed with polymer is used to enhance the physical properties of the LCs materials. These materials possess combined application of LC and polymer and their electro-optic applications have been extensively studied during last decades. The LC mixture consists of Nematic and Cholestric that are dispersed in a monomer or prepolymer with different concentration. The existing Polymer Dispersed Liquid Crystal (PDLC) consists of different concentrations of LC and monomer. The textures and Phase transition temperature (PTTs) can be studied by Polarising Microscope Studies (PMS). The Phase transition temperature (PTTs) can also be studied by Fabry-Perot etalon Scattering Studies (FPSS) In this paper, we present the changes in transition temperature along with new phase transition temperature in PDLC. Measurements were performed for both heating and cooling of various samples. In addition to this, Refractive Index (RI) of all samples were found for optical characterization of the material. Texture observation and spectroscopic techniques are used to characterize the other properties of the PDLC samples. The PDLC suspension can be used as a new liquid crystalline material that does not require any additional alignment processing or treatment. Our results will provide new opportunity and their uses in advanced technology development.
Investigation of AFLCs using Fabry-Perot etalon
The spectroscopic technique using the Fabry-Perot [FPSS] etalon coupled with a spectrometer has been used to determine the mesophase transition temperatures of the samples (1) MHPB(H)PBC (2) MHPB(Cl)PBC. Earlier FPSS work on the sample MHPOBC(R) is also substantiated here with results from Differential Scanning Calorimetery [DSC] and Polarization Microscopy Studies [PMS]. A comparison of the results obtained with those of DSC clearly indicates the success of the FPSS technique in determining the transition temperatures of the above samples belonging to the FLCs and AFLCs groups. The photographs of the textures using PMS also support the above results. This novel technique has led to the detection of new mesophase transitions in addition to those reported by DSC and PMS. These new findings are also corroborated by the analysis of the thermal runs using DSC and the textures from PMS.
Phase characterisation of simulated high burn-up UO2 fuel
Abstract To determine the lattice constant variation with burn-up and the oxidation behaviour at high temperatures, simulated UO2-spent fuels with burn-ups up to 200 GWd tM−1 were prepared by cold pressing and sintering and characterised by X-ray diffraction analysis and thermogravimetry. The fcc-lattice parameter of the sintered samples determined at room temperature, showed a continuous decrease with the simulated burn-up. During oxidation the conversion of the simulated fuels to the (U,FP)4O9 and (U,FP)3O8-type phases was strongly delayed when the simulated burn-up exceeded 80 GWd tM−1. Also, at high burn-ups (>100 GWd tM−1), large fractions of the (U,FP)4O9-type phase remained untransformed to (U,FP)3O8 after prolonged exposure to air at 950–1000°C. This suggests a marked widening of the (U,FP)4O9-phase field when the amount of substituted uranium atoms exceeds values of about 8%.