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This diploma thesis is focused on issues concerning the stability of selected vegetable oils which are used in cosmetic industry. The stability of eight oils without additives were determined by a differential scanning calorimeter. In the first phase, the temperatures of oil degradation were determined for different rates of heating, i.e. nonisothermal stabilities. They were consequetly used to calculate isothermal stabilities alias induction periods. The calculation of induction periods was completed by using integral isoconversional methods, which applied four different temperature functions. One of the temperature functions corresponded to Arrhenius equation while the others to non-Arrhenius functions. The confrontation of induction periods under standart conditions showed that an optimal temperature function to calculate oil stabilities is one of the non-Arrhenius functions in exponential form. We can state that all oils are degraded by similar, if not the same, mechanism. The specified stabilities, in periods of months, have proved the importance of using stabilizers and other additives in the commercial and technological use of vegetable oils.

The formation of liquid films is a widely known problem in aluminium heat exchanger materials. The phenomenon results in decreased brazeability along with severely deteriorated mechanical properties which might cause assembly collapse. In addition, low-melting-point elements like tin, bismuth and lead are thought to promote grain boundary sliding which is the main deformation mechanism during brazing. Their melting characteristics are not adequately reported in literature. It is therefore of great importance to examine the behaviour of these elements.The main objectives with this work is melting range determination of fin heat exchanger materials, melting detection of low-melting-point elements and calculation of tin, bismuth and lead solid-solubility in aluminium. This work does also involve distribution analysis of such elements in aluminium matrix after heat treatment.These investigations require development of a differential scanning calorimetry (DSC) technique that is applicable for analysis of aluminium fin heat exchanger material containing low-melting-point elements on ppm level. Optimization of the technique includes parameter control; like heating rate, sample mass, reproducibility and choice of crucible material. Laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) is additionally used in order to analyse solid solubility and distribution of low-melting-point elements in aluminium after heat treatment.The developed DSC technique shows a sensitivity limit in the range of 260-600 ppm. It means that it is not possible to detect melting of phases within and below that range. Solid solubility of tin was calculated for the three heat treatment temperatures, 400°C, 500°C and 625°C. Same procedure was applied on bismuth and lead. However, calculated values did not agree with Thermo-Calc. The distribution analysis indicate an exudation of trace elements i.e. diffusion toward surface during heat treatment.In conclusion, more knowledge regarding liquid films in aluminium fin heat exchanger material was obtained. Future work should be to further optimize the DSC technique for trace element analysis for concentrations below 100 ppm. The LA-ICP-MS technique is likely to improve experimentally unverified binary phase diagrams like Al-Bi, Al-Pb and Al-Sn phase diagrams. It can also be used to study exudation behaviour of liquid films.

<div>Several truck fires have occurred in recent years involving bridges with reinforced and prestressed concrete components. If the fire burns for a significant period of time (15 minutes or more), bridge inspectors and engineers must determine if the exposure to elevated temperature has reduced the strength and serviceability of the concrete components. Little guidance is available, however, correlating the results of field inspections with the actual condition of the reinforced/prestressed concrete elements. This dissertation presents the results of a research program conducted to develop rational guidance for inspectors and engineers to evaluate concrete bridge elements after a fire event and help them make informed decisions regarding the future status of the bridge. <br></div><div><br></div><div>The research program includes tests on portions of a reinforced concrete deck and three full-scaled AASHTO Type I prestressed girders acquired from a decommissioned highway bridge. In addition, six pretensioned concrete prismatic beam specimens with varying levels of prestress were fabricated and tested. The specimens had cross-sectional dimensions of 8 in. by 8 in. and were designed to simulate the bottom flanges of common I-shaped prestressed concrete bridge girders. The deck specimens and four (of the six) concrete beam specimens were subjected to elevated temperatures using radiation-based heaters. Two (of the six) prismatic specimens built in the laboratory were subjected to a hydrocarbon pool fire test conducted in the field for using approximately 135 gallons of kerosene. The concrete temperature profiles and the deformations of the specimens were measured using thermocouple trees and displacement transducers, respectively. Concrete samples were also cored and examined using various methods (DSC and SEM) to correlate microstructure degradation (microcracking, dehydration of C-S-H, decomposition of calcium hydroxide, etc.) with the measured temperatures through the depth of the specimens. <br></div><div><br></div><div>To evaluate the residual loading-carrying capacities of prestressed concrete girders after being subjected to fire, a hydrocarbon pool fire test was performed on two decommissioned AASHTO Type I girders in the field. Load tests were then conducted on the prestressed girders under both ambient and post-fire conditions. After structural testing, material tests were also conducted on concrete cores taken from the girders to evaluate the post-fire concrete microstructure alteration. Furthermore, three-dimensional finite element models were developed to predict the residual load-carrying capacities and overall structural responses of prestressed concrete bridge girders after being exposed to fire. Results from the numerical models generally agree favorably with experimental observations and provide insights into the behavior of the specimens. A parametric study was performed using the benchmarked finite element models to expand the database and establish design recommendations further. Capacity influence lines for load-carrying capacities and structural stiffness were developed and discussed.</div><div><br></div><div>Based on the results from this research, guidelines for the post-fire assessment of prestressed concrete bridges are included in this dissertation along with a step-by-step checklist. Bridge inspectors can infer the extent of damage to prestressed concrete bridge girders in the event of a fire and develop a post-fire assessment plan cognizant of the findings. In most cases, no more than 1.0 in. of the concrete from the exposed surface undergoes material damage / deterioration due to loss of CH, cracking, and spalling. The impact on the strength of prestressed concrete girders is relatively minor based on experimental results. Their initial stiffness, however, will likely be reduced. <br> </div><br>

Today, in the automotive industry, many of the interior parts in the car are made of ABS and PC/ABS polymeric blend. These materials are used in the areas for example: instrument panels, tunnel consoles and door panels. The extensive use of these materials means that it is important to gain in-depth knowledge about the materials,their properties; and also their behaviour when in contact with different chemicals andat different conditions.This study aims to address the potential problem of the polymers used in the interiorof the car - ABS and PC/ABS cracking due to environmental factors. This study proposes to introduce a low-cost test method to compare the polymeric materials and choose the best one for future purposes with the environmental circumstances in mind for materials to have a good service life.During the thesis project, ABS and PC/ABS samples were tested for environmental stress cracking to compare the strained materials against PEG 400 and an assemblyfluid chemical. These tests were conducted at three different temperature levels.Differential Scanning Calorimetry (DSC) was used to verify the polymeric materialsthat the samples were made of. Optical microscope and FTIR were employed to analyzethe samples for crazes / cracks and degradation of material, respectively.This thesis helped in establishing a good starting point for ESC testing of different materials for the organization. The test method was used to test the failure of material sin ESC. It was observed that the chemicals used for the testing were aggressive and accelerated the cracking process in the materials rapidly. Another observation of the tests was that high strain also caused the materials to fail quickly. While comparing the materials, PC/ABS polymer blend was more resistant than ABS materials to cracking when exposed to same strain level during the creep rupture test (test in absence ofchemicals acting as a reference test for ESC).

Curcumin is the major phenolic diarylheptane derivative in Curcuma longa and has been reported to possess pharmacological activities. Unfortunately this compound suffers from poor bioavailability and rapid neutral-alkaline degradation. Co-crystal of curcumin is one option under exploration, motivated by the fact that a number of active pharmaceutical ingredient (API) co-crystals with improved dissolution have recently been synthesized. Hence, co-crystallization technique highlights an alternative means to improve the performance of curcumin. Within our work evidences for a co-crystal was ascertained from DSC, Kofler hot stage screening and PXRD, and all confirmed a new crystal phase could have been formed between curcumin and a co-crystallizing agent, nicotinamide. We report that re-crystallization step essentially aids the purification of commercial curcumin, a herbal based actives. Otherwise the prevalence of a new crystal phase in solvent-mediated co-crystallization will be significantly reduced. Besides, phase diagram is an effective tool for the study of solubility behaviours in co-crystal system. In order to acquire related techniques, fenbufen, a poorly water soluble drug, was selected. The result showed the huge difference in solubility between fenbufen and nicotinamide lead to difficulty in the construction of phase diagram.

New resin-based composites and resin-infiltrated ceramics are used to fabricate computer-aided design (CAD) and computer-aided manufacturing (CAM)-based restorations, although little information is available on the long-term performance of these materials. The aim of this investigation was to determine the effects of storage time (24 h, 90 days, 180 days) on the thermophysical properties of resin-based CAD/CAM materials. Thermogravimetric Analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used in the study. TGA provided insight into the composition of the resin-based materials and the influence of internal plasticization and water sorption. Resin-based composites showed different decomposition, heat energy and mechanical behavior, which was influenced by storage time in water. Individual materials such as Grandio bloc showed lower influence of water storage while maintaining good mechanical properties.

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