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Advanced polymeric and wood-derived composites : structure, processing, and application Jalaee, Adel
Abstract
Incorporating biobased reinforcements into polymer matrices offers a promising route to mitigate plastic waste while improving the performance of commodity and engineering polymers. This thesis presents a comprehensive strategy for designing high-performance, sustainable composites using wood-derived fillers such as cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), unbleached kraft pulp fibers (PF), bleached chemi-thermomechanical pulp (BCTMP), and sawdust (SD) in polyamide 6 (PA6) and polypropylene (PP) matrices. A solvent-free processing approach, combining cryogenic and planetary ball milling, was developed to achieve uniform dispersion and strong interfacial interactions between hydrophilic fibers and hydrophobic polymers. In PA6 systems, CNF incorporation led to a 60% increase in tensile strength and a Young’s modulus of 2.9 ± 0.2 GPa at only 1 wt% loading. Sequential ball milling of pulp fibers enhanced stiffness by 160%, while CNC modification further increased modulus to 4.3 GPa without compromising processability. In PP systems, premilled BCTMP fillers eliminated the need for conventional compatibilizers such as maleic anhydride-grafted polypropylene (MAPP). This approach overcame thermal degradation challenges, delivering up to a 200% increase in stiffness at 30 wt% loading while preserving strength. Additionally, BCTMP acted as a nucleating agent, promoting crystallinity within the polymer matrix. Sawdust, an abundant residual material, demonstrated significant potential in PP composites. A premixing strategy enabled mechanical interlocking between sawdust particles and PP, maintaining thermal stability and increasing the onset degradation temperature by ~30% compared to MAPP-based systems. Notably, this work achieved the successful 3D printing of PP composites containing 40 wt% sawdust, overcoming the clogging issues typically associated with wood-filled filaments. In parallel, this thesis advances additive manufacturing by formulating 3D-printable inks composed of ball-milled sawdust and CNCs. The inks exhibited favorable rheological properties for high-resolution direct ink writing (DIW), retaining structural integrity even at 75 wt% sawdust. Post-print freezing enabled tunable anisotropic porous structures, while surface functionalization with UiO-66-NH2 and fluorinated silanes imparted water repellency and outstanding oil sorption capacity (up to 120 g/g). Altogether, this work introduces scalable, eco-friendly processing routes for manufacturing advanced wood-based composites, bridging structural reinforcement, environmental remediation, and functional applications in sustainable materials engineering.
Item Metadata
Title |
Advanced polymeric and wood-derived composites : structure, processing, and application
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Creator | |
Supervisor | |
Publisher |
University of British Columbia
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Date Issued |
2025
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Description |
Incorporating biobased reinforcements into polymer matrices offers a promising route to mitigate plastic waste while improving the performance of commodity and engineering polymers. This thesis presents a comprehensive strategy for designing high-performance, sustainable composites using wood-derived fillers such as cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), unbleached kraft pulp fibers (PF), bleached chemi-thermomechanical pulp (BCTMP), and sawdust (SD) in polyamide 6 (PA6) and polypropylene (PP) matrices. A solvent-free processing approach, combining cryogenic and planetary ball milling, was developed to achieve uniform dispersion and strong interfacial interactions between hydrophilic fibers and hydrophobic polymers.
In PA6 systems, CNF incorporation led to a 60% increase in tensile strength and a Young’s modulus of 2.9 ± 0.2 GPa at only 1 wt% loading. Sequential ball milling of pulp fibers enhanced stiffness by 160%, while CNC modification further increased modulus to 4.3 GPa without compromising processability. In PP systems, premilled BCTMP fillers eliminated the need for conventional compatibilizers such as maleic anhydride-grafted polypropylene (MAPP). This approach overcame thermal degradation challenges, delivering up to a 200% increase in stiffness at 30 wt% loading while preserving strength. Additionally, BCTMP acted as a nucleating agent, promoting crystallinity within the polymer matrix.
Sawdust, an abundant residual material, demonstrated significant potential in PP composites. A premixing strategy enabled mechanical interlocking between sawdust particles and PP, maintaining thermal stability and increasing the onset degradation temperature by ~30% compared to MAPP-based systems. Notably, this work achieved the successful 3D printing of PP composites containing 40 wt% sawdust, overcoming the clogging issues typically associated with wood-filled filaments.
In parallel, this thesis advances additive manufacturing by formulating 3D-printable inks composed of ball-milled sawdust and CNCs. The inks exhibited favorable rheological properties for high-resolution direct ink writing (DIW), retaining structural integrity even at 75 wt% sawdust. Post-print freezing enabled tunable anisotropic porous structures, while surface functionalization with UiO-66-NH2 and fluorinated silanes imparted water repellency and outstanding oil sorption capacity (up to 120 g/g).
Altogether, this work introduces scalable, eco-friendly processing routes for manufacturing advanced wood-based composites, bridging structural reinforcement, environmental remediation, and functional applications in sustainable materials engineering.
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Genre | |
Type | |
Language |
eng
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Date Available |
2025-09-08
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0450073
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URI | |
Degree (Theses) | |
Program (Theses) | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2025-11
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International