Date of Award

Spring 5-10-2025

Level of Access Assigned by Author

Open-Access Thesis

Language

English

Degree Name

Doctor of Philosophy (PhD)

Department

Forest Resources

First Committee Advisor

Mehdi Tajvidi

Second Committee Member

Douglas J. Gardner

Third Committee Member

Douglas W. Bousfield

Additional Committee Members

Islam Hafez

Jinwu Wang

Abstract

Climate change and plastic pollution represent critical threats impacting human health and the environment. Buildings contribute significantly to greenhouse gas emissions through energy consumption and carbon-intensive materials, where synthetic insulation and packaging products exacerbate plastic pollution. Sustainable alternatives derived from renewable resources are urgently needed to mitigate these issues. This dissertation explores the potential of lignocellulosic materials and cellulose nanofibrils (CNFs) to develop eco-friendly insulation panels and foams, replacing hazardous petrochemical and energy-intensive mineral-based products. Utilizing the inherent binding and foam-stabilizing properties of CNFs, novel wood fiber-based insulation boards, composite panels, and foams were fabricated and comprehensively characterized. Initially, low-density insulation panels were successfully produced using CNFs, lignin-containing CNFs (LCNFs), starch, and combinations of these binders. Vacuum-assisted filtration followed by controlled pressing yielded panels exhibiting excellent mechanical and thermal insulation properties. The panels showed promising mechanical performance, with CNF-bonded formulations outperforming others. The incorporation of LCNFs allowed partial replacement of CNFs without significant performance loss. Additionally, water resistance and thickness swelling were optimized through wax incorporation. Notably, pilot-scale trials demonstrated the feasibility of commercial-scale production, confirming scalability. Subsequently, building upon insights from initial studies, CNF-reinforced thermomechanical pulp (TMP) fiber-based composite panels were developed

with enhanced mechanical and fire-resistant properties. Panels fabricated through wet and semi-dry processes exhibited significantly improved mechanical performance upon densification and a facile lamination method. Adding gypsum or clay (up to 50%) and aluminum hydroxide notably enhanced thermal stability, fire resistance, and mechanical properties, meeting or exceeding commercial gypsum board standards. CNFs facilitated mineral retention within the fiber network, enabling uniform dispersion across the panel even at higher ratios. Further, leveraging CNFs' foam stabilization capability, lignocellulosic foams with superior thermomechanical, sound absorption, and cushioning characteristics were developed. Optimization of TMP fibers, CNFs, surfactant, and solids content resulted in foams matching or surpassing the performance of synthetic expanded polystyrene (EPS). The interaction among constituents significantly influenced foam stability, bubble structure, density, and resultant mechanical strength. Specifically, optimized foams with 10 wt.% solids, 10% CNFs, and 2 g/L surfactant demonstrated remarkable thermal insulation, sound absorption, mechanical integrity, and thickness recovery. Finally, biobased foams' mechanical, cushioning, and water stability properties were further enhanced using additives like Acrodur®, FeCl3, and cationic polyacrylamide (CPAM). Specifically, formulations with FeCl3 or CPAM as additives exhibited significant improvements in water resistance, resilience, and mechanical strength, highlighting the potential for practical packaging applications. This dissertation highlights the promising potential of CNF-reinforced lignocellulosic composites as sustainable, high-performance alternatives to petrochemical-based insulation, building, and packaging materials, significantly contributing to efforts mitigating climate change and plastic pollution.

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