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The static and dynamic electrical behaviour, the electrical conductivity, the macroscopic viscosity and the optical transmission characteristics of side chain polysiloxane liquid crystal polymers (LCPs) have been studied. Particular emphasis has been placed on the study of the molecular dynamics using dielectric relaxation spectroscopy and the low field (AC) and high field (DC) conductivity, with the intention of relating structural variations to the behaviour of these materials, and of identifying the most appropriate LCPs for use in practical optical storage devices. The effect on the molecular dynamics of the polymer backbone and the core, spacer and end groups of the mesogenic units was investigated. The LCP responses were shown to be broadly similar to those of low molar mass liquid crystals, though with longer relaxation times. The dynamic responses of structurally different LCPs were shown to be related when these were observed at a temperature referenced to the glass transition temperature. Values of the static permittivity of several LCPs have also been measured and tabulated. Low field electrical conductivity measurements were used to show that the magnitude of the conductivity was comparable to that of commercial liquid crystals. A method was identified whereby the conductivity of different LCPs could be compared. The texture of the measuring electrode surface was found to play an important role in determining the impedance of electrical double layers formed near the surface of the sample, with smooth polymer based surfactants reducing the formation of space charge. High field DC conductivity measurements showed that Schottky-type charge emission occurred at the electrodes at elevated temperatures, except when the smooth polymer based surfactants were present. This was probably a result of the reduction in the local field near the electrode due to a better physical match at the LCP/surfactant interface. The bulk viscosity of mixtures of an LCP and commercial liquid crystal were also measured and the results extrapolated to the viscosity of the LCP. The relationship between electrical conductivity and bulk viscosity was examined. The optical absorption spectra of blue pleochroic dyes have been measured to identify appropriate dyes for use with LCPs in laser written optical memories. The stability of the alignment of selected LCPs with time and temperature was also observed optically.

Agriculture and Agri-Food Canada (AAFC), the Ontario Greenhouse Vegetable Growers Association (OGVG), and Queen’s University’s Solar Calorimetry Laboratory (SCL) are undertaking a joint project to evaluate the energy and crop-yield benefits of operating commercial greenhouses in isolation from the outdoor environment, i.e., eliminating natural or forced ventilation to the exterior. Implementing such a scheme requires “closing” the greenhouse envelope and the installation of an active air-conditioning system to control temperature and moisture levels that could be harmful to crop growth. To this end, a prototype air-conditioning system, centered around a liquid desiccant dehumidifier, was designed, constructed and instrumented such that its thermal and functional performance could be evaluated over extended periods. The prototype unit was installed in a “research” greenhouse located at the Agriculture Canada, Greenhouse and Processing Crops Research Center (GPCRC) located in Harrow, Ontario. Both the novel air-conditioning and monitoring systems were implemented during the course of the thesis and operated for two preliminary crop trials to characterize system performance and identify aspects needing further refinement. Data obtained over these two initial periods, indicated that, the latent and sensible cooling capacity of the novel desiccant system averaged: 2.25 kW and -0.25 kW, respectively, during the severe summer trial; and 1.25 kW and -0.1 kW, respectively, during the milder spring trial. Values obtained from the preliminary monitored data also indicate that the liquid desiccant unit operated at electrical and thermal coefficients of performance (COPs) between 0.74 and 3.1 and between 0.15 and 0.52, respectively. Finally, using the monitored data, a simple regression-based empirical model was formulated to describe the average performance of the liquid desiccant unit. This was attempted to illustrate how performance results could be generalized to assist in the future design of similar commercial-scale systems. The results of this part of the thesis indicated, however, that further test data is required to confidently characterize the unit’s performance. As well, it was concluded that addition instrumentation (specifically, the addition of a meter to measure the flowrate of the regenerator air-stream) would enhance the potential to develop a practical performance correlation. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-11-01 14:12:54.326

Vapor-liquid equilibria (VLE) in alkanes and alcohols was measured and a contribution Patel-Teja (GPT) equation proposed in this work. systems of nmodified Group of state was Isothermal vapor-liquid equilibria at temperatures between 298.7K and 333. 7K have been measured for the binary systems n-pentane + n-hexane. n-pentane + noctane. n-pentane + n-decane. and n-pentane + l-propanol. The data were found to be consistent according to a point-to-point consistency test and were correlated using the Wilson. NRTL. and UNIQUAC activity coefficient models. The parameters of the models were estimated using the maximum likelihood principle. A new version of the Group contribution Patel-Teja equation of state was proposed in which a new temperature dependent group interaction expression was introduced. Group interaction parameters for four constituent groups of the alcohols and n-alkanes (viz. CH 2• CH 3 • CH and OH) were determined. These parameters were then used for the prediction of VLE in mixtures of n-alkane + n-alkane. n-alkane + n-alcohol. and n-alcohol + n-alcohol. VLE predictions with the new GPT equation of state were found to be superior to predictions with the original group contributions with molecular equations. The modified equation can be used in systems of nalkanes and alcohols where data for molecular parameters are lacking. The proposed temperature dependence of the group interaction parameters improved predictions over a wide range of temperature and pressure.

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