Theses and Dissertations at Montana State University (MSU)
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Item Material properties of ureolytically induced calcium carbonate adhesives(Montana State University - Bozeman, College of Engineering, 2023) Anjum, Sobia; Chairperson, Graduate Committee: Robin Gerlach; This is a manuscript style paper that includes co-authored chapters.Polymers used in adhesive applications are often petrochemical-based and release volatile organic compounds (VOCs) during application. These VOCs can accumulate indoors to the detriment of human health. Biopolymers potentially offer a non-toxic and sustainable alternative to synthetic polymers but generally have limited physical stability and low mechanical performance. One of the methods of improving the stability and adhesive performance of biopolymers is the addition of a mineral phase to reinforce biopolymer adhesives. In this work, biomineral-reinforced biopolymer adhesives were produced by ureolytically induced precipitation of calcium carbonate in the presence of guar gum and soy protein. The microbially and enzymatically induced ureolysis was carried out by the ureolytic bacterium, Sporosarcina pasteurii, or by jack bean urease. The resulting adhesives were referred to as ureolytically induced calcium carbonate precipitation (UICP)-reinforced adhesives and specifically microbially and enzymatically induced calcium carbonate (MICP and EICP)- reinforced adhesives. The adhesive strength of these composite adhesives was optimized by varying calcium and cell (or enzyme) concentrations. The adhesive strength of biomineral reinforced guar gum and soy protein biopolymers was up to 2.5 and 6 times higher than the adhesive strength of the biopolymers alone, respectively. The durability of the MICP-reinforced adhesives was tested after varying immersions (24 h and 7 days), relative humidities (50 and 80% RH), and temperatures (-20, 100, and 300?C). The durability of the MICP-reinforced adhesives, upon immersion, was significantly improved compared to biopolymer alone, and maintained their adhesive strength at moderate humidities and from below-freezing to room temperatures after 7- day exposures. To determine the effect of biopolymers on the nanoscale material properties of biomineral aggregates, enzymatically induced calcium carbonate precipitation was induced in the presence of a standard protein, Bovine Serum Albumin (BSA). Nanoindentation and Atomic Force Microscopy show that the moduli of the mineral precipitates were significantly lowered in the presence of BSA. Atomic force microscopy also showed that BSA introduced structural variations and moduli gradation in biominerals. These results demonstrate that the presence of a protein additive, specifically BSA, can alter the nanoscale structure and material properties of calcium carbonate precipitates. Using an organic additive to manipulate microscale material properties of biominerals offers possibilities for advanced control at the microscale and enhanced toughness at the macroscale for engineering applications such as in construction, binder, and adhesive applications.Item Influence of pretreatment, lignin extraction, and chemical modification on lignin properties and the performance of lignin-formaldehyde resins and lignin-PLA composite materials(Montana State University - Bozeman, College of Engineering, 2022) Saulnier, Brian Keith; Chairperson, Graduate Committee: David Hodge; This is a manuscript style paper that includes co-authored chapters.Bio-ethanol can be produced from lignocellulosic biomass in a biorefinery as part of a three step process, a chemical or mechanical pretreatment, enzymatic hydrolysis of the cell wall, and fermentation of these sugars to ethanol. One of the byproducts of this process is lignin, a complex biopolymer composed of a heterogeneous aromatic structure. Lignin is often burned to provide energy for the biorefinery. Incorporating lignin into higher-value products is crucial to the viability of the biorefinery process and the full utilization of the renewable carbon contained in biomass. Challenges to the inclusion of lignin in value-added products include recalcitrance of the cell wall to deconstruction and lignin extraction, heterogeneity of the lignin chemical structure, polydisperse molecular weight distributions, and low reactivity. In this thesis we address these challenges by using feedstock selection, selection of pretreatment and lignin extraction process conditions, lignin fractional precipitation, and direct chemical modification of lignin. Chapter 1 provides an overall introduction and background of previous work. Chapter 2 uses a diverse panel of corn stover genotypes subjected to dilute acid pretreatment using a variety of process conditions. The response of the biomass to pretreatment was characterized with special attention given to glucose hydrolysis yields and p-coumarate (pCA) content. Chapter 3 uses a single corn stover source pretreated using a variety of dilute acid conditions followed by two different lignin extraction methods. The influence of pretreatment and lignin extraction conditions on lignin properties was characterized with focus on lignin pCA content. This study found that lignin-formaldehyde resins using lignin from optimized process conditions achieved lap shear strengths higher than conventional phenol-formaldehyde resins. Chapter 4 addresses lignin polydispersity and heterogeneity using the fractional precipitation of lignin from formic acid liquors to obtain differing molecular weight lignin fractions while allowing for successful enzymatic hydrolysis of cellulose. Chapter 5 uses fractional precipitation of corn stover alkali liquors along with modification using propylene carbonate to obtain a panel of multi-component biopolymer fractions for manufacture of biopolymer-PLA composite materials. These materials were fully characterized finding materials made with modified biopolymers exhibited better lignin dispersion, and improved thermal and mechanical properties.Item Effects of substratum topography on bacterial adhesion(Montana State University - Bozeman, College of Engineering, 1996) Scheuerman, Teresa RushItem Molecular characterization of the primary adhesion mechanisms that direct [gamma/delta] T cells to epithelial-associated tissues(Montana State University - Bozeman, College of Agriculture, 1994) Walcheck, Bruce KennethItem Bacterial specific adhesion of Staphylococcus epidermidis onto human fibronectin under uniform flow(Montana State University - Bozeman, College of Engineering, 1999) Wang, Grace Tein-yaItem Measuring antimicrobial efficacy against sulfate-reducing bacterial biofilms(Montana State University - Bozeman, College of Engineering, 1999) Gardner, Lawrence RobertItem Regulation of leukocyte L-selectin expression(Montana State University - Bozeman, College of Agriculture, 1993) Palecanda, Aiyappa MuthannaItem Demonstration of the leukocyte-endothelial cell adhesion cascade involved in lymphocyte recirculation and neutrophil and lymphocyte localization to sites of inflammation(Montana State University - Bozeman, College of Agriculture, 1994) Bargatze, Robert FrostItem Adhesion of Pseudomonas aeruginosa to surface modified and unmodified polystyrene with and without a conditioning layer(Montana State University - Bozeman, College of Engineering, 1999) Thompson, Jenny KathleenItem Effects of initial adhesion events on the physiology of Pseudomonas aeruginosa(Montana State University - Bozeman, College of Agriculture, 2001) Pulcini, Elinor deLancey