Theses and Dissertations at Montana State University (MSU)
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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 Modeling of resin transfer molding of composite materials with oriented unidirectional plies(Montana State University - Bozeman, College of Engineering, 1996) Humbert, Dell RaymondItem Mold filling parameters in resin transfer molding of composites(Montana State University - Bozeman, College of Engineering, 1994) Hedley, Charles WilliamItem Development and validation of a dry-fiber bundle test method(Montana State University - Bozeman, College of Engineering, 2000) Parkins, Dallas WarrenItem Fiberglass composite tensile fatigue resistance : fiber surface damage analysis and fatigue resistant fiber coating(Montana State University - Bozeman, College of Engineering, 1996) Bian, JinhuaItem Effects of in-plane fiber waviness on the static and fatigue strength of fiberglass(Montana State University - Bozeman, College of Engineering, 2001) Wang, LeiItem Mixed mode delamination of glass fiber/polymer matrix composite materials(Montana State University - Bozeman, College of Engineering, 2003) Agastra, Pancasatya; Chairperson, Graduate Committee: John F. MandellItem High cycle longitudinal and transverse figure of unidirectional glass/polyester composites(Montana State University - Bozeman, College of Engineering, 1995) Wei, GuangxuItem Effects of ply drops on the fatigue resistance of composite materials and structures(Montana State University - Bozeman, College of Engineering, 1997) Scott, Mark EthanItem Long term fatigue of glass fiber reinforced composite materials for wind turbine blades(Montana State University - Bozeman, College of Engineering, 1991) Reed, Robert Michael