Session: 02-04: Building Performance Analysis and Simulation

Paper Number: 131506

131506 - Structure-Property Relationships of Lignin-Based Structural Materials for Buildings 

Abstract: 

Buildings facilitate the prolonged sequestration of carbon owing to their extended lifespans surpassing 50 years. Engineered wood, encompassing wood biopolymer composites, stands as a promising substitute for concrete and steel in construction to mitigate CO₂ emissions. Nevertheless, the prevailing formaldehyde-based binders employed in engineered wood pose toxicity issues and environmental risks, underscoring the imperative to explore bio-based, formaldehyde-free alternatives. Lignin, an abundant biopolymer on Earth, serves as a natural adhesive in supporting a plant's structural integrity. Presently, Kraft lignin is relegated as a low-value waste by the paper and pulp industry, with a substantial portion incinerated for fuel. Leveraging lignin from waste streams and agricultural residues for building materials emerges as a cost-effective resolution. However, the chemical composition of lignin proves sensitive to the lignocellulose source and extraction method, resulting in inherent variability. The extraction of lignin through ionic liquids (IL) or deep eutectic solvents (DES) is both environmentally friendly and energy efficient. Nevertheless, the impact of lignin variability on adhesive performance remains underexplored. Moreover, biopolymer-based composites face challenges at various levels. At the molecular level, the complex and heterogeneous structure of biopolymers, which include non-reactive units, can limit reactivity and lead to brittleness. At the particle level, biopolymer particles are polydisperse, have low surface area and reactivity, and tend to aggregate. At the composite-level, challenges include poor interfacial adhesion, particle/fiber heterogeneity, poor processability, thermal instability, and water retention. The properties of composites depend on manufacturing processes and involve a complex architecture with fillers, pores, and resin-rich layers. Specifically, the optimal characteristics for developing structural wood composites have not undergone systematic examination. To address this research gap, the present study endeavors to establish structure-property relationships for lignin-based adhesives sourced from diverse origins and extraction methods. The investigation encompasses a comprehensive baseline characterization of distinct lignin types, coupled with assessments of mechanical strength in lignin-based adhesives. 2D Hetero Single Quantum Coherence (HSQC) Nuclear Magnetic Resonance (NMR) spectroscopy is performed to gain information of the chemical structures present as well as the relative compositions of the different chemical groups. Adhesives are prepared using each of the distinct lignins and tested using repeated lap-shear strength tests for five specimens each. The mechanical strength of the adhesives is correlated with fundamental chemical composition of lignin to establish structure-property correlations. This study is crucial for delineating the path toward the development of high-strength, low-carbon embodied materials, that play a pivotal role in decarbonizing the building sector.

Presenting Author: Malavika Bagepalli Lawrence Berkeley National Laboratory

Presenting Author Biography: Dr. Malavika Bagepalli is a Rosenfeld Building Science Fellow at Lawrence Berkeley National Laboratory. Malavika's research focuses in carbon capture and storage using building materials. Malavika earned a Ph.D. in Mechanical Engineering from Georgia Institute of Technology, where her research aimed at investigating high temperature granular flows for solar thermal energy transport and storage.

Authors:

Malavika Bagepalli Lawrence Berkeley National Laboratory
Priscilla Pieters University of California, Berkeley
Jian Zhang Lawrence Berkeley National Laboratory
Kevin Miller Murray State University
Hemant Choudhary Lawrence Berkeley National Laboratory
Blake Simmons Lawrence Berkeley National Laboratory
Sumanjeet Kaur Lawrence Berkeley National Laboratory