<p> The polymerization of styrene to polystyrene was studied using gamma radiation from a Co^60 source as the free radical initiator. Conversions up to 50% were obtained and the molecular weight distribution, intrinsic viscosity, bulk viscosity, and osmotic pressure of several samples were measured. A theoretical kinetic model was developed using a slightly modified conventional kinetic scheme and employing a viscosity correction for the termination rate constant. The model predicts conversion over the range studied and molecular weight distributions are in agreement within the limitations of the experimental equipment to measure this parameter.</p> / Thesis / Master of Engineering (MEngr)

<p> The transient behaviour of a batch stirred-tank reactor (BSTR) for free radical polymerization of styrene in toluene has been studied experimentally and theoretically. A kinetic model applicable to high conversions was developed using data from measurements of monomer conversion and molecular weight distribution (MWD). Significant improvement over the conventional kinetic model is obtained when the viscosity or gel effect is accounted for. The termination rate constant and catalyst efficiency are allowed to vary with viscosity. The findings agree with the general theory of diffusion-controlled reaction which predicts that viscosity is the most important parameter.</p> / Thesis / Master of Engineering (MEngr)

<p> Polymerization of bulk styrene initiated thermally as well as with di-tertiary-butyl peroxide was studied in isothermal batch reactors. Thermal polymerization was carried out at 100, 140, 170 and 200°C while polymerization with di-tertiary butyl peroxide was at 100 and 140°C. A kinetic model was derived therefrom accounting for initiation reactions from a first order decomposition of catalyst and a second order reaction between two monomer molecules to form two monoradicals, propagation, chain transfer to monomer and termination by combination only. Gel effect was allowed by the variation of rate constants with conversion. Both the thermal initiation rate constant and the first order decomposition rate constant of di-tertiary butyl peroxide were found to agree with literature values with the present values slightly higher. The initial rate constants for propagation, chain transfer to monomer, and termination were extrapolated to the range, 100-200°C using literature data. This kinetic model was used in the simulation of polymer reactor systems studying the effect of recycle and operating conditions on the molecular weight distribution and rate of production of polymer products.</p> <p> The main body of this thesis reports the polymerization study and the development of the kinetic model. The details of the kinetic equations and methods of solution, experimental techniques involved, and the simulation of polymer reactor systems are reported in the Appendices.</p> / Thesis / Doctor of Philosophy (PhD)

<p> The free radical polymerization of styrene in benzene using azo-bisisobutyronitrile as a catalyst has been studied both theoretically and experimentally. The molecular-weight distribution and conversion are predicted on the basis of a simplified kinetic mechanism, neglecting a number of minor side reactions. The steady-state assumption is investigated and is shown to be applicable in the case of styrene polymerization, a pseudo-steady-state being reached in less than one second. Using the steady-state approach a relatively simple kinetic model is obtained, suitable for computer simulation. The prime variables consist of the ordinary reaction conditions such as monomer concentration, solvent concentration, catalyst concentration, reaction temperature and reaction time.</p> <p> The polymerization was carried out isothermally in a stirred batch reactor from which samples were abstracted at various time intervals. Conversion was determined by precipitating the polymer with methanol, filtering, and weighing, and the molecular-weight distribution has been obtained by gel-permeation chromatography. A computer program was written to interpret the variation of refractive index with respect to the elution volume trace from the chromatograph, giving a readout of molecular chain length in monomer units versus weight fraction.</p> <p> The experimentally obtained conversion and distribution curves are compared with those obtained from the mathematical model. Except for bulk polymerization agreement between the two is good. Good agreement for conversion is obtained for all cases if the catalyst initiation efficiency is adjusted according to the monomer or solvent concentration. However, the same considerations do not give good agreement for molecular-weight distribution. Rather it appears that the rate constants instead of the catalyst efficiency are monomer or solvent concentration dependent, which would explain the discrepancies.</p> / Thesis / Master of Engineering (MEngr)

<p> The polymerization of styrene initiated with gamma radiation as well as thermal initiation was studied at temperatures, 150, 155, 160, 165, 180 and 200C and dose rates of 0.072-0.1836 M Rads/hour. In all cases the reactions were studied up to 100% conversion and the following results were obtained. (1) Rate of polymerization was independent of dose rate. (2) 165C was considered to be the temperature at which the radiation polymerization system in the case of styrene reaches a limiting rate of initiation caused by high temperature and dose rate. (3) Self-production of ethynylbenzene in the system at 200C probably caused retardation of the initial rate of polymerization. (4) No significant gel effect was observed in the investigated temperature range. (5) Polystyrene produced by radiation at high temperatures has a very low average molecular weight. (6) A general mechanism was proposed based on the characteristics of the reactions. (7) A temperature range was proposed as an optimal reaction temperature for radiation polymerization of styrene. </p> / Thesis / Master of Engineering (MEngr)

<p> Polymerization of styrene was carried out in continuous and batch reactors using azobisis obutyronitrile as initiator and benzene as solvent. Monomer conversion, molecular weight distribution (MWD) and viscosity were measured.</p> <p> Corrections to the conventional kinetic mechanism using results from the continuous reactor were determined. These corrections were applied to the batch reactor kinetic model and the conversion and MWD thus predicted were compared to experimental results. It was found that the corrections applied to the batch system were not adequate to give accurate predictions of conversion and MWD.</p> <p> A short computer study of the effect of oscillating monomer flow and temperature, as opposed to steady flow, on a transient continuous reactor was also carried out. It was found from this study that at low conversions oscillations in monomer flow will not affect the time average conversion and molecular weight. Oscillations in temperature caused an increase in time average conversion and a decrease in time average molecular weight as compared to results obtained when the reactor was operated at a steady temperature which was the average of the oscillating temperatures.</p> / Thesis / Master of Engineering (MEngr)

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Thermal and fatigue cracking are pavement distresses that deteriorate asphalt pavements in Canada. However, the current AASHTO M320 standard specification protocol does not give satisfactory correlation between the properties measured in the laboratory to thermal and fatigue cracking performance of the asphalt in service. This thesis is aimed at validating the newly developed MTO LS-299 and LS-308 specification test methods for predicting pavement distress. A secondary objective is to determine how well laboratory-aged and field-aged binders correlate with each other in terms of their chemical and physical properties. Chemical testing using infrared (IR) spectroscopy and X-ray fluorescence (XRF), as well as physical and mechanical testing using the regular bending beam rheometer (BBR), extended BBR (eBBR), dynamic shear rheometer (DSR), and double edge notched tension (DENT) tests were performed on laboratory-aged and recovered binders from Highway 417. Asphalt cements with significant amounts of waste engine oil residues as determined by XRF data were found to have cracked severely due to their high tendency for chemical aging. Western Canadian binders modified with styrene-butadiene-styrene polymer showed low affinity for both chemical and physical aging as determined from their carbonyl indices. Asphalt binders with smaller paraffinic structures exhibited insignificant pavement deterioration while the opposite occurred to those with low aromatic indices according to their IR data. The DSR data show that chemical aging occurs much faster in the laboratory-aged binders than the field-aged binders. The DENT test is able to separate superior performing binders from inferior ones with 86% accuracy according to their CTOD data. The regular BBR gave poor correlation between the laboratory test methods and the performance of the pavements. Good correlation exists between the laboratory test methods and the performance of the pavements in service according to the eBBR data. Pavements without any cracks showed lower grade losses, while pavements with severe thermal cracking recorded higher grade losses after three days of conditioning prior to testing. The study has shown that the eBBR and DENT tests are better tools for predicting pavement performance and provide good specification tests for the control of thermal and fatigue cracking in modern pavements. / Thesis (Master, Chemistry) -- Queen's University, 2012-02-28 13:16:02.222

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24642号 / 工博第5148号 / 新制||工||1983(附属図書館) / 京都大学大学院工学研究科化学工学専攻 / (主査)教授 大嶋 正裕, 教授 竹中 幹人, 教授 佐野 紀彰 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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