Soy flour (SF), a by-product of the soybean oil extraction processing, was investigated for its application in soy-polypropylene composites for interior automotive applications. The emphasis of this work was the understanding of this new type of filler material and the contribution of its major constituents to its thermal stability and impact properties. For this reason, reference materials were selected to represent the protein (soy protein isolate (SPI)) and carbohydrate (soy hulls (SH)) constituents of the soy flour. Additional materials were also investigated: the residue obtained after the protein removal from the soy flour which was called insoluble soy (IS), and the remaining liquid solution after acid precipitation of the proteins, containing mostly sugars and minerals, which was called soluble sugar extract (SSE). Two treatments, potassium permanganate and autoclave, were analyzed for their potential to modify the properties of the soy composite materials. An acid treatment with sulfuric acid conducted on soy flour was also considered. The soy materials were studied by thermogravimetric analysis (TGA) under isothermal (in air) and dynamic (in nitrogen) conditions. SPI had the highest thermal stability and SSE the lowest thermal stability for the early stage of the heating process. Those two materials had the highest amount of residual mass at the end of the dynamic TGA in nitrogen. The two treatments showed minimal effect on the isothermal thermal stability of the soy materials at 200 ??C. A minor improvement was observed for the autoclave treated soy materials. Fourier transformed infrared (FTIR) spectroscopy indicated that the chemical surface composition differed according to type of the soy materials but no difference could be observed for the treatments within one type of soy material. Contact angle analysis and surface energy estimation indicated differences of the surface hydrophobicity of the soy materials according to type of material and treatment. The initial water contact angle ranged from 57 ?? for SF to 85 ?? for SH. The rate of water absorption increased dramatically after the autoclave treatment for IS and SPI. Both materials showed the highest increase in the polar surface energy fraction. In general, the major change of the surface energy was associated with change of the polar fraction. After KMnO4 treatment, the polar surface energy of SF, IS and SPI decreased while SH showed a slight increase after KMnO4 treatment. A relationship between protein content and polar surface energy was observed and seen to be more pronounced when high protein containing soy materials were treated with KMnO4 and autoclave. Based on the polar surface energy results, the most suitable soy materials for polypropylene compounding are SPI (KMnO4), SH, and IS (KMnO4) because their polar surface energy are the lowest which should make them more compatible with non-polar polymers such as polypropylene. The soy materials were compounded as 30 wt-% material loading with an injection moulding grade polypropylene blend for different combinations of soy material treatment and coupling agents. Notched Izod impact and flexural strength as well as flexural modulus estimates indicated that the mechanical properties of the autoclaved SF decreased when compared to untreated soy flour while the potassium permanganate treated SF improved in impact and flexural properties. Combinations of the two treatments and two selected (maleic anhydride grafted polypropylene) coupling agents showed improved impact and flexural properties for the autoclaved soy flour but decreased properties for the potassium permanganate treated soy flour. Scanning electron microscopy of the fractured section, obtained after impact testing of the composite material, revealed different crack propagation mechanisms for the treated SF. Autoclaved SF had a poor interface with large gaps between the material and the polypropylene matrix. After the addition of a maleic anhydride coupling agent to the autoclaved SF and polypropylene formulation, the SF was fully embedded in the polymer matrix. Potassium permanganate treated SF showed partial bonding between the material and the polymer matrix but some of the material showed poor bonding to the matrix. The acid treated SF showed cracks through the dispersed phase and completely broken components that did not bind to the polypropylene matrix. In conclusion, the two most promising soy materials in terms of impact and flexural properties improvement of soy polypropylene composites were potassium permanganate treated SF and the autoclaved SF combined with maleic anhydride coupling agent formulation.

In the present work, novel dewatering aids and a novel centrifuge configuration were developed and applied for the purpose of dewatering fine particles. Three different types dewatering reagents were tested in different filtration and centrifugation units. These chemicals included low-HLB surfactants, naturally occurring lipids, and modified lipids. Most of these reagents are insoluble in water; therefore, they were used in solutions of appropriate solvents, such as light hydrocarbon oils and short-chain alcohols. The role of these reagents was to increase the hydrophobicity of the coal and selected mineral particles (chalcopyrite, sphalerite, galena, talc, clay, phosphate, PCC and silica) for the dewatering. In the presence of these reagents, the water contact angles on the coal samples were increased up to 90o. According to the Laplace equation, an increase in contact angle with the surfactant addition should decrease the capillary pressure in a filter cake, which should in turn increase the rate of dewatering and help reduce the cake moisture. The use of the novel dewatering aids causes a decrease in the surface tension of water and an increase in the porosity of the cake, both of which also contribute to improved dewatering. A series of batch-scale dewatering tests were conducted on a variety of the coal and mineral samples using the novel dewatering aids. The results obtained with a Buchner funnel and air pressure filters showed that cake moistures could be reduced substantially, the extent of which depends on the particle size, cake thickness, drying time, reagent dosage, conditioning time, reagent type, sample aging, water chemistry, etc. It was determined that use of the novel dewatering aids could reduce the cake formation time by a significant degree due to the increased kinetics of dewatering. At the same time, the use of the dewatering aids reduced the cake moistures by allowing the water trapped in smaller capillaries of the filter cake. It was found that final cake moistures could be reduced by 50% of what can be normally achieved without using the reagents. However, the moisture reduction becomes difficult with increasing cake thickness. This problem can be minimized by applying a mechanical vibration to the cake, spraying a short-chain alcohol on the cake and by adding a small amount of an appropriate coagulant, such as alum and CaCl2 to the coal and mineral slurries. The novel dewatering aids were also tested using several different continuous filters, including a drum filter, disc filter and horizontal belt filter (HBF). The results obtained with these continuous filtration devices were consistent with those obtained from the batch filters. Depending on the coal and mineral samples and the type of the reagent, 40 to 60% reductions in moisture were readily achieved. When using vacuum disc filters, the cake thickness increased substantially in the presence of the novel dewatering aids, which could be attributed to the increased kinetics of dewatering. A dual vacuum system was developed in the present work in order to be able to control the cake thickness, which was necessary to achieve lower cake moistures. It was based on using a lower vacuum pressure during the cake formation time, while a full vacuum pressure was used during the drying cycle time. Thus, use of the dual vacuum system allowed the disc filter to be used in conjunction with the novel dewatering aids. Its performance was similar to that of HBF, which is designed to control cake thickness and cake formation time independently. The effectiveness of using the novel dewatering aids were also tested in a full-continuous pilot plant, in which coal samples were cleaned by a flotation column before the flotation product was subjected to the disc filter. The tests were conducted with and without using novel dewatering aids. These results were consistent with those obtained from the laboratory and batch-scale tests. The novel centrifuge developed in the present work was a unit, which combined a gravity force and air pressure. The new centrifuge was based on increasing the pressure drop across the filter cake formed on the surface of the medium (centrifuge wall). This provision made it possible to take advantage of Darcy s law and improve the removal of capillary water, which should help lower the cake moisture. A series of tests were conducted on several fine coal and mineral particles and obtained more than 50% moisture reduction even at very fine particle size (2 mm x 0). Based on the test results obtained in the present work, two proof-of-concept (POC) plants have been designed. The first was for the recovery of cyclone overflows that are currently being discarded in Virginia, and the other was for the recovery of fines from a pond in southern West Virginia. The former was designed based on the results of the plant tests conducted in the present work. Cost vs. benefit analyses were conducted on the two POC plants. The results showed very favorable internal rates of return when using the novel dewatering aids. Surface chemistry studies were conducted on the coal samples based on the results obtained in the present investigation. These consisted mainly of the surface characterization of the coal samples (surface mineral composition, surface area, zeta potential, x-ray photoelectron microscopy (XPS)), acid-base interactions of the solids and liquids, dewatering kinetic tests, contact angle measurements of the coal samples and surface force measurements using AFM. In addition, carbon coating on a silica plate using palsed laser deposition (PLD) and Langmuir-Blodgett (LB) film deposition tests were conducted on the sample to better understand the surfactant adsorption and dewatering processes. The test results showed that the moisture reductions on the fine particles agree well with the surface chemistry results. / Ph. D.