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.
A model for predicting heat transfer through gypsum‐board/wood‐stud walls exposed to fire
To facilitate the development of cost-effective and flexible design options there is a need to develop models to predict the fire resistance of wood-frame building assemblies. Such assemblies often derive much of their fire resistance from a protective membrane composed of gypsum board. A simple two-dimensional computer model is presented to predict heat transfer through gypsum-board/wood-stud walls exposed to fire. Input data for the thermophysical properties of gypsum board were measured exploying standard bench-scale tests. Input data for wood were selected from the literature. Small-and full-scale fire resistance tests were conducted on gypsum-board/wood-stud wall assemblies to provide data for the validation of the model. The model is shown to predict heat transfer through these walls rather well.