Polymer composites are fast becoming a material in the manufacturing of automotive interior and exterior parts such as facias and dashboard components. Production of rigid structural foams are ideal because they reduce the overall weight as well as reduce the amount of material used to manufacture the part. Polymer-clay nanocomposites are a classification of materials containing a blend of polymer and a small weight percentage of nanoclay. These materials are currently of interest to automotive part manufacturers because they are known to deliver improved mechanical properties and increase foamability of a polymer. The current study investigates the changes in material properties and the foamability of a thermoplastic polyolefin (TPO)-clay nanocomposite as the degree of intercalation was varied. The TPO-clay nanocomposite was produced by melt blending TPO, nanoclay and maleic anhydride grafted polypropylene (MAHgPP) in a co-rotating twin screw extruder. The material was subjected to a multi-pass process to vary the degree of intercalation. Degree of intercalation was tracked by rheology, XRD and TEM micrographs. Part density, cell density and flexural modulus measurements were performed on foamed and non-foamed injection molded bars to observe changes in the foamability of the material. Material was also processed without clay and analyzed in the same manner. Through TEM and XRD analysis it was found that the degree of intercalation and delamination was varied with increasing number of passes. Rheological measurements showed that the TPO-clay nanocomposite underwent (beta)-scission and intercalation simultaneously. The changes in intercalation had a positive effect on the foamability of the TPO-clay nanocomposite. As well, the TPO-clay nanocomposite experienced an increase in flexural properties for both unfoamed and foamed parts compared to the TPO-PPgMAH blend; TPO-clay nanocomposite experienced a 44% and 23% increase in the flexural modulus for unfoamed and foamed parts respectively. Data also showed that there was a limit to the number of times the TPO-clay nanocomposite can be recycled before the foamability of the material begins to decrease, which was attributed to material degradation. / Thesis / Master of Applied Science (MASc)

Caseinate powders have been well accepted because of their foaming properties. In this study, 10% solution of reconstituted skim milk powder (SMP) chelated with sodium hexametaphosphate (SHMP) and trisodium citrate (TSC) at 1 mEq, 50 mEq, and 100 mEq were prepared to conduct a comparison with sodium caseinate, potassium caseinate, and calcium caseinate solutions. Foamability, foam stability as well as the preferential locations of αs-casein, β-casein and !-casein in their foams were analyzed. It was hypothesized that the foamability, foam stability and the preferential locations of these three caseins in the milk foams are different from treatment to treatment. Milk foam was generated with an air- injection method at a flow rate of 0.30 L/M for 18 seconds. Foam stability was measured through half-life method. The foam composition was quantified with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method. Analysis of Variance (ANOVA) test results concluded that there were no significant differences detected in foamability (p>0.05). On the other hand, foam stability differed significantly among the treatments. Foams of reconstituted SMP-treated with 1 mEq SHMP and TSC were significantly more stable compared to other treatments (p < 0.05), β-casein (p>0.05) and !-casein (p>0.05). In conclusion, the addition of calcium chelating salts might increase the foamability to the same level as caseinate solutions. Furthermore, the study proved that the combination of calcium chelating salts and chelator levels is able to alter the foam stability.

A good slag practice is essential for production of a high-quality stainless steel. In addition, the electrical and material efficiency of the electric arc furnace (EAF) can considerably be improved by a good slag practice. The metallurgical properties of the slag are strongly influenced by its high-temperature microstructure. Thus, characterization of the phases within the EAF slag as well as the determination of the amount of these phases is of high importance.In addition, the knowledge about the chemical composition of the liquid slag and solid phases at the process temperatures is instrumental in developing a good slag practice.In order to study the slag in EAF high-chromium stainless steelmaking, slag samples were collected from 14 heats of AISI 304L steel (two samples per heat) and 7 heats of duplex steel (three samples per heat).The selected slag samples were petrographically studied both using scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS) and light optical microscopy (LOM). In some cases, X-ray diffraction (XRD) analyses were also performed. Moreover, computational thermodynamics was used to determine the equilibrium phases in the EAF steelmaking slags at the process temperatures. In addition, parameter studies were performed on the factors influencing the equilibria.More specifically, a petrographical and thermodynamic characterization was performed on the EAF austenitic steelmaking slags. Thereafter, the microstructural evolution of the slag during the EAF duplex steelmaking process was investigated. Moreover, an investigation with focus on the total amount of precipitates within the high-chromium stainless steelmaking slags was done. Finally, the foamability of these slags was quantified and evaluated.The petrographic investigations showed that, during the refining stage, in both austenitic and duplex cases, the main constituent of the EAF slag is a melt consisting of liquid oxides. In addition, the slag samples contain solid spinel particles. However, before ferrosilicon-addition (FeSi), the slag may also contain solid stoichiometric calcium chromite. Moreover, depending on the slag basicity, the slag may contain solid dicalcium silicate at the process temperatures.The evolution of the slag during the refining stage of the EAF was graphically illustrated in the calculated isothermal phase diagrams for the slag system Al2O3-Cr2O3-CaO-MgO-SiO2-TiO2.It was found that the only critical parameter affecting the amount of solid spinel particles in the slag is the chromium-oxide content. More specifically, it was shown that the amount of the spinel particles in the slag increases with an increased chromium-oxide content of the slag. It wasvialso shown that a higher basicity and a lower temperature of the slag contribute to the dicalcium silicate precipitation.In order to evaluate and quantify the foamability of the slags, the slag’s physical properties influencing its foaming index were determined. Computational thermodynamics was used as a tool to calculate the weight fractions of the solid phases within the slag at different EAF process stages. The computational thermophysics was used to estimate the viscosity of the liquid part of the slag samples at the process temperatures. The apparent viscosity of the samples was calculated by combining the above results. By estimating the density, surface tension and the foaming-gas bubble size, the foaming index of the slag samples were quantified. It could be shown that the foaming index of the EAF high-chromium stainless steelmaking slag may be on its minimum as the slag’s basicity takes a value in the range of 1.2 – 1.5. A basicity value of around 1.50 – 1.60 can be suitable for enhancing the foaming index of the slag, during the refining period in EAF high-chromium stainless steelmaking.

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