Polymer Science Commons^™

Design And Characterization Of Lignin-Based, Thermoresponsive Soft Composites With Improved Mechanical And Transport Properties, Missoury D. Wolff

All Dissertations

In an attempt to reduce reliance on petroleum-based polymers, lignin – an abundant biopolymer – has gained popularity as a sustainable alternative. However, research on lignin-containing soft composites – i.e., hydrogel (bio)composites – has largely been heuristic, providing limited insight into the fundamental structure-processing-property relationships that govern performance improvements in this emerging class of ‘green’ soft composites. As such, this dissertation presents a systematic investigation of how lignin molecular weight (MW), composite composition, and the concentrations of crosslinker and accelerator impact the mechanical and transport characteristics of soft composites composed of lignin, poly(N-isopropylacrylamide) (PNIPAm), and poly(vinyl alcohol) (PVA).

In the …

Isolation And Upgrading Of Lignin From Agricultural Sources Using Phase Equilibria, Bronson Lynn

All Dissertations

In the emerging bioeconomy, agricultural residues from our nationwide crop harvests are positioned to be a cornerstone of renewable and sustainable fuels, chemicals, and materials. However, to be economically viable, the basic constituents of this plant matter must be separated and funneled to the appropriate application to maximize value and overall usability.

This work focuses on the component that has, to this point, been largely left behind: lignin. Although it is the most abundant aromatic biopolymer on the planet, making up 15-40% of grasses, hardwoods, and softwoods, the processing involved to isolate usable lignins is too complex and expensive to …

Elucidating The Impact Of Casting Solvent On Vanadium Ion Transport In Solution-Cast Ionomer Biocomposites Containing Lignin, Zhongyu Wang

All Theses

This paper attempts to investigate the influence of solvent choice to the Nafion-lignin proton exchange membranes that used in the vanadium redox flow batteries. The influence of two different solvents: DMF and DMSO were investigated in this paper. Results show that when using DMSO as solvent, Nafion-lignin membranes' vanadium ion cross over can be greatly reduced in comparing with membranes prepared from DMF. Also, membranes prepared from DMSO also show higher water uptake ability and lower ion exchange capacity than the membranes prepared from DMF. This paper has also investigated the influence of lignin type to the membranes. Results show …

Biomass Derived Lignin Polymer Modification For Sustainable Chemical Engineering Applications, Samantha Glidewell, Keisha Walters

Chemical Engineering Undergraduate Honors Theses

Lignin is an abundant naturally occurring plant-based polymer that is branched, highly unsaturated, and rich in aliphatic and aromatic hydroxyl groups. Lignin is a significant byproduct of the wood pulp and paper industries; however, it has yet to be widely utilized in commercial applications due to its non-linear structure, broad range of molecular weights, hydrophobicity, high rigidity, and brittleness. Recent investigations into modifying lignin to broaden its potential uses have shown promising results. This thesis explores different modification techniques of the naturally occurring hardwood lignin polymer for specific applications in areas of water treatment and polyurethane (PU) production. The first …

Green Chemistry Design Of Epoxies From Biomass For Circular Economy, Kavya Ganesan

All Dissertations

The commercial epoxies market in automobiles has been growing mainly in terms of usage as automotive coatings and lightweight composite structures manufacturing. Most of these commercial epoxies are bisphenol-based. Bisphenol-based epoxies are a class of high-performance polymer materials that, when cured, yield thermosets with high mechanical, thermal and chemical resistance properties. Roughly, North America produces around 123 billion pounds of these epoxies which are used in various industrial applications like coatings, composites, structural parts, automotive, electronics, construction etc. These epoxies are mainly manufactured from bisphenol-A (BPA) and epichlorohydrin (EPH). These raw materials are sourced from fossil fuel resources and are …

Amine-Functionalized Lignin-Based Ionomer Nanocomposites For Redox Flow Batteries, Joshua Wilder

All Theses

As the development of energy storage technologies for renewable energy sources continues to garner attention, vanadium redox flow batteries (VRFBs) have emerged as promising source for grid-scale energy storage. A major component of the VRFB is the ion exchange membrane (IEM), as it serves to physically separate the two liquid electrolytes and also directly impacts the battery’s capacity, efficiency, and cost. The current industry standard IEM, Nafion™, not only accounts for a large portion of the cost of the VRFB but also suffers from poor proton selectivity. Herein, we have synthesized sulfonated poly(ether ether ketone) (SPEEK) composite membranes containing amine …

Development Of Lignin-Based Copolymers And Polymer Blends, David Chem

Graduate Theses and Dissertations

Increasing industrial interest in reducing fossil fuels in virgin polymer production and incorporating bio-based polymeric materials has led researchers to explore the potential of utilizing plant-based polymers such as lignin. Chapter 1 of this thesis presents a comprehensive overview of copolymerization and blending techniques for lignin and synthetic polymers, emphasizing different types of modifications and copolymerization techniques as well as key parameters such as temperature, reaction time, pH level, and solution compositions. These valorization methods are directed towards the development of high-value lignin-based materials with properties well-suited for various commercial applications. Chapter 2 offers a fundamental exploration into the amination …

Activated Carbon Synthesis From Lignin-Rich Byproduct Streams Of Biorefineries, Chengjun Wu

All Dissertations

Over the past decade, the production of biofuels from lignocellulosic biomass has steadily increased to offset the use of fuels from petroleum. To make biofuels cost-competitive, it is necessary to add value to the “ligno-” components (up to 30% by mass) of the biomass. Instead of just burning it for heat and electricity generation, direct conversion of lignin carbon into a product provides a complementary path to carbon capture, promoting a more environmentally conscious approach. However, the utilization of these lignin-rich byproduct streams, which are separated from the biofuels production, for industrial products can be challenging. The use of specific …

Improving Lignin Recovery From Paper Mill And Biorefinery Waste Streams Via Liquid-Phase Splitting, Carter Fitzgerald

All Dissertations

Lignin is an abundant biopolymer with significant promise due to its aromaticity. It has been targeted as a replacement for a number of petroleum-based products including adhesives, coatings, polyurethane foams, activated carbon, and carbon fibers. However, commercially available bulk lignins are too polydisperse, and contain too many residual metals from the pulping process that are detrimental to the properties of the final product.

The Sequential Liquid-lignin Recovery and Purification (SLRP) process was developed by Michael Lake and John Blackburn, in collaboration with Clemson, with the intention of creating a continuous method for recovering lignin from paper-mill black liquors. Thies and …

Characterization Of Lignin And Cellulose Biopolymers Structure – Function Relationships, Zachariah Pittman

All Dissertations

Biomass is vital to ongoing efforts to secure a sustainable future. While many of our efforts focus on finding alternative forms of energy, biomass among them, only biomass has the potential to serve as a sustainable materials feedstock. However, biomass is heterogenous, complicating the upgrading processes needed to manufacture commodity and performance products. For example, plant biomass consists largely of cellulose, a crystalline polysaccharide, and lignin, a highly stable polyaromatic. The specific properties of cellulose and lignin depend greatly on the plant, harvesting conditions, and isolation procedures. Thus, accurate and reliable determination of the fundamental properties of biomass is crucial …

Elucidating The Mechanical And Transport Properties Of Lignin-Based Hydrogel Composites, Nicholas Gregorich

All Dissertations

The use of lignin in the fabrication of soft composites has become an emerging area of research in polymer science and polymer chemistry. These lignin-based materials present numerous benefits, notably, a reduction in the use of petroleum-based precursor, improved structural benefits to otherwise soft host polymers, as well as the inherent antimicrobial and antioxidant properties of lignin, making it suitable for biomaterials. Herein, we present two chemical reaction pathways of incorporating lignin that was fractionated and cleaned using the Aqueous Lignin Purification with Hot Agents (ALPHA) process into poly(vinyl alcohol) (PVA) hydrogel composites for aqueous-based separations. By leveraging the ALPHA …

Structure And Dynamics Of Lignin In Condensed Phase For Biomass Conversion, Nusrat Jahan

Theses and Dissertations

Lignocellulosic biomass represents the largest potential volume and lowest cost for biofuel and biochemical production. Harnessing the full potential of the lignocellulosic biomass for low-carbon energy requires the knowledge of efficient breakdown and fractionation of its carbohydrates and lignin. Organic solvent pretreatment is recognized as an emerging way ahead because of its inherent advantages, such as the ability to fractionate lignocellulosic biomass into cellulose, lignin, and hemicellulose components with high purity, as well as easy solvent recovery and solvent reuse. Through all-atom MD simulation, we analyze the conformational transition of diverse lignin molecules in varying concentration of Methanol/water , DMSO/water …

Carbon Fibers From Bio-Based Precursors Derived From Renewable Sources, Sagar Kanhere

All Dissertations

Carbon fibers have the highest strength and modulus among all known fibers and are used as reinforcements in high-performance composites [1]. Carbon fibers also have a very low density relative to metals. Therefore, carbon fibers possess ultrahigh specific strength and modulus, which make them desirable for high-performance light-weight composites. A vast majority of commercial carbon fibers are produced from PAN precursors that are expensive, which limits the use of PAN-derived carbon fibers to aerospace applications (e.g., airplanes). However, for costsensitive applications, there is a need for low-cost, moderate performance carbon fibers. Lignin is a low-cost by-product of pulping and biorefining …

Recovering And Upgrading Kraft Lignin For Application In Flexible Polyurethane Foam, Peng Quan

Dissertations, Master's Theses and Master's Reports

Lignin is the second abundant natural polymer and has been highlighted as a potential substitute for fossil-based raw materials. However, the inherent molecular heterogeneity and the complex recovery processes result in the challenge of controlling the molecular properties and value-added applications of lignin in large scale. To address those issues, a novel acid-liquefaction process was developed in this study to recover Kraft lignin with improved molecular homogeneity directly from black liquor.

In the first study, the liquefaction parameters were screened based on yield and molecular weight properties of the recovered lignin. Then, the recovered lignin samples were used to replace …

Degumming Of Hemp Fibers Using Combined Microwave Energy And Deep Eutectic Solvent, Bulbul Ahmed

LSU Master's Theses

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali …

Multienzyme Immobilized Polymeric Membrane Reactor For The Transformation Of A Lignin Model Compound, Rupam Sarma, Md. Saiful Islam, Mark P. Running, Dibakar Bhattacharyya

Chemical and Materials Engineering Faculty Publications

We have developed an integrated, multienzyme functionalized membrane reactor for bioconversion of a lignin model compound involving enzymatic catalysis. The membrane bioreactors were fabricated through the layer-by-layer assembly approach to immobilize three different enzymes (glucose oxidase, peroxidase and laccase) into pH-responsive membranes. This novel membrane reactor couples the in situ generation of hydrogen peroxide (by glucose oxidase) to oxidative conversion of a lignin model compound, guaiacylglycerol-β-guaiacyl ether (GGE). Preliminary investigation of the efficacy of these functional membranes towards GGE degradation is demonstrated under convective flow mode. Over 90% of the initial feed could be degraded with the multienzyme immobilized membranes …