Scholarly Works, Sustainable Biomaterials

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3D printing of lignin: Challenges, opportunities and roads onward
Ebers, L. -S.; Arya, Aditi; Bowland, C. C.; Glasser, Wolfgang G.; Chmely, S. C.; Naskar, A. K.; Laborie, Marie-Pierre Genevieve (2021-06)
As the second most abundant biopolymer on earth, and as a resource recently becoming more available in separated and purified form on an industrial scale due to the development of new isolation technologies, lignin has a key role to play in transitioning our material industry towards sustainability. Additive manufacturing (AM), the most efficient-material processing technology to date, has likewise made great strides to promote sustainable industrial solutions to our needs in engineered products. Bringing lignin research to AM has prompted the emergence of the nascent "lignin 3D printing" field. This review presents the recent state of art of this promising field and highlights its challenges and opportunities. Following a review of the industrial availability, molecular attributes, and associated properties of technical lignins, we review R&D efforts at implementing lignin systems in extrusion-based and stereolithography (SLA) printing technologies. Doing so underlines the adage of lignin research that "all lignins are not created equal," and stresses the opportunity nested in this chemical diversity created mostly by differences in isolation conditions to molecularly select and tune the attributes of technical lignin systems towards desirable properties, be it by modification or polymer blending. Considering the AM design process in its entirety, we finally propose onward routes to bring the full potential to this emerging field. We hope that this review can help promote the unique value and overdue industrial role of lignin in sustainable engineered materials and products.
Amorphous solid dispersions of enzalutamide and novel polysaccharide derivatives: investigation of relationships between polymer structure and performance
Wilson, Venecia R.; Lou, Xiaochun; Osterling, Donald J.; Stolarik, DeAnne F.; Jenkins, Gary J.; Nichols, Brittany L. B.; Dong, Yifan; Edgar, Kevin J.; Zhang, Geoff G. Z.; Taylor, Lynne S. (Nature Research, 2020-10-28)
Amorphous solid dispersion (ASD) is a widely employed formulation technique for drugs with poor aqueous solubility. Polymers are integral components of ASDs, but mechanisms by which polymers lead to the generation and maintenance of supersaturated solutions, which enhance oral absorption in vivo, are poorly understood. Herein, a diverse group of newly synthesized cellulose derivatives was evaluated for their ability to inhibit crystallization of enzalutamide, a poorly soluble compound used to treat prostate cancer. ASDs were prepared from selected polymers, specifically a somewhat hydrophobic polymer that was extremely effective at inhibiting drug crystallization, and a less effective, but more hydrophilic, crystallization inhibitor, that might afford better release. Drug membrane transport rate was evaluated in vitro and compared to in vivo performance, following oral dosing in rats. Good correlation was noted between the in vitro diffusion cell studies and the in vivo data. The ASD formulated with the less effective crystallization inhibitor outperformed the ASD prepared with the highly effective crystallization inhibitor in terms of the amount and rate of drug absorbed in vivo. This study provides valuable insight into key factors impacting oral absorption from enabling ASD formulations, and how best to evaluate such formulations using in vitro approaches.
Amphiphilic hydroxyalkyl cellulose derivatives for amorphous solid dispersion prepared by olefin cross-metathesis
Dong, Yifan; Mosquera-Giraldo, Laura I.; Troutman, Jacob; Skogstad, Brittny; Taylor, Lynne S.; Edgar, Kevin J. (Royal Society of Chemistry, 2016-07-07)
Olefin cross-metathesis (CM) has enabled design and synthesis of diverse, amphiphilic cellulose ether derivatives (e.g. of ethyl and methyl cellulose). In this paper, hydroxyalkyl cellulose was selected as a hydrophilic starting material, with the additional advantage that it has DS (OH) 3.0 that allows targeting of a full range of DS of selected functional groups. Hydroxypropyl cellulose (HPC) was first etherified with 5-bromopent-1-ene to attach olefin “handles” for metathesis, whereby control of molar ratios of sodium hydride and 5-bromopent-1-ene permits full DS control of appended olefin. These olefin-terminated HPC ethers then were subjected to CM with acrylic acid and different acrylates, followed by diimide hydrogenation to reduce the resulting α,β-unsaturation. NMR and FT-IR spectroscopies were useful tools for following reaction progress. One of the product carboxyl-functionalized HPC derivatives, designated HPC-Pen106-AA-H, showed high promise as a crystallization inhibitor of the antiviral drug telaprevir. Its nucleation-induction inhibitory ability was compared to those of commercial controls, HPC and HPMCAS. All three polymers were very effective for inhibiting telaprevir crystallization, increasing induction time up to 8-fold. HPC did not effectively prevent amorphous particle growth, whereas the carboxyl-containing HPC-Pen106-AA-H and HPMCAS were able to prevent formation of agglomerates of amorphous drugs.
Analysis of electricity consumption: a study in the wood products industry
Quesada, Henry Jose; Wiedenbeck, Janice K.; Bond, Brian H. (2016-10)
This paper evaluates the effect of industry segment, year, and US region on electricity consumption per employee, per dollar sales, and per square foot of plant area for wood products industries. Data was extracted from the Industrial Assessment Center (IAC) database and imported into MS Excel. The extracted dataset was examined for outliers and abnormalities with outliers outside the quantile range 0.5-99.5 dropped from the analysis. A logarithmic transformation was applied to eliminate the skewness of the original data distributions. Correlation measurements indicated a moderate association between the response variables; therefore, a multivariate analysis of variance test was performed to measure the impact of the three factors: industry type, year, and region, simultaneously on all response variables. The results indicated some effect associated with all three factors on the three measures of electricity consumption. Subsequently, univariate ANOVA tests were conducted to determine the levels of the factors that were different. Most levels of industry type were associated with significantly different energy consumption, an expected result since some of the industries are more energy intensive than others. The industries in Standard Industry Code (SIC) 2493 (reconstituted wood products) are the groups with the highest electricity consumption with means of 38,096.28 kWh/employee, 0.86 kWh/sales, and 154.14 kWh/plant area while industries grouped in SIC 2451 (mobile homes) have the smallest consumption with means of 6811.01 kWh/employee, 0.05 kWh/sales, and 9.45 kWh/plant area. Interestingly, differences in regional consumption were found to be linked to the proportion of industry types by region. Data analysis also indicated differences in electricity consumption per employee for the factor year, but for the other response variables, no differences were found. These main results indicate that industries in the wood products sector have different electricity consumption rates depending on the type of manufacturing processes they use. Therefore, industries in this sector can use these comparisons and metrics to benchmark their electricity consumption as well to understand better how electricity costs might vary depending on the region they are located.
Barriers, enablers and market governance: A review of the policy landscape for repair of consumer electronics in the EU and the U.S.
Svensson-Hoglund, Sahra; Richter, Jessika Luth; Maitre-Ekern, Eleonore; Russell, Jennifer D.; Pihlajarinne, Taina; Dalhammar, Carl (2021-03-15)
Many strategies have been proposed to support the transition to a Circular Economy (CE). In most cases, circular design and product life-extension practices specify repair as an essential element. In both the EU and the U.S., policymakers are attempting to increase the amount of repairs made, through the introduction of recent EU Ecodesign regulation changes and proposed US Right to Repair legislation. This review explores the current policy landscape for repair services by first outlining legal and market barriers to stakeholder participation in repair activities, and which stakeholders are affected. The review reveals a wide range of fundamental obstacles to both supply and demand of repair, including Intellectual Property, Consumer, Contract, Tax and Chemical laws, along with issues of design, consumer perceptions and markets. Subsequently, the current and proposed policy solutions to address barriers and increase repair activities are reviewed. A comparative assessment of the EU and the U.S. is followed by a discussion on the current repair market governance structure, which is found to be primarily centralized (i.e. repair services concentrated with manufacturers), with possible implications for upscaling repair. New policy proposals challenge this governance. Introducing the concept of a Repair Society Framework as a market transformation tool, we comprehensively discuss the current state of repair and provide an outlook for research and policy in this area. (C) 2020 The Authors. Published by Elsevier Ltd.
Bioactive Cellulose Nanocrystal-Poly(epsilon-Caprolactone) Nanocomposites for Bone Tissue Engineering Applications
Hong, Jung Ki; Cooke, Shelley L.; Whittington, Abby R.; Roman, Maren (2021-02-25)
3D-printed bone scaffolds hold great promise for the individualized treatment of critical-size bone defects. Among the resorbable polymers available for use as 3D-printable scaffold materials, poly(epsilon-caprolactone) (PCL) has many benefits. However, its relatively low stiffness and lack of bioactivity limit its use in load-bearing bone scaffolds. This study tests the hypothesis that surface-oxidized cellulose nanocrystals (SO-CNCs), decorated with carboxyl groups, can act as multi-functional scaffold additives that (1) improve the mechanical properties of PCL and (2) induce biomineral formation upon PCL resorption. To this end, an in vitro biomineralization study was performed to assess the ability of SO-CNCs to induce the formation of calcium phosphate minerals. In addition, PCL nanocomposites containing different amounts of SO-CNCs (1, 2, 3, 5, and 10 wt%) were prepared using melt compounding extrusion and characterized in terms of Young's modulus, ultimate tensile strength, crystallinity, thermal transitions, and water contact angle. Neither sulfuric acid-hydrolyzed CNCs (SH-CNCs) nor SO-CNCs were toxic to MC3T3 preosteoblasts during a 24 h exposure at concentrations ranging from 0.25 to 3.0 mg/mL. SO-CNCs were more effective at inducing mineral formation than SH-CNCs in simulated body fluid (1x). An SO-CNC content of 10 wt% in the PCL matrix caused a more than 2-fold increase in Young's modulus (stiffness) and a more than 60% increase in ultimate tensile strength. The matrix glass transition and melting temperatures were not affected by the SO-CNCs but the crystallization temperature increased by about 5.5 degrees C upon addition of 10 wt% SO-CNCs, the matrix crystallinity decreased from about 43 to about 40%, and the water contact angle decreased from 87 to 82.6 degrees. The abilities of SO-CNCs to induce calcium phosphate mineral formation and increase the Young's modulus of PCL render them attractive for applications as multi-functional nanoscale additives in PCL-based bone scaffolds.
A Case Study to Determine Drivers and Barriers of Appalachian Forest Products in Central America
Quesada, Henry Jose; Lyon, Scott; Smith, Robert (Instituto Tecnologico De Costa Rica, 2012-06-04)
The purpose of this research was to determine drivers and barriers of Appalachian wood product competitors in Central America. Potential market opportunities for Appalachian forest product companies in Central America were evaluated and strategies were developed to increase exports of Appalachian wood products to Central America. The findings support the claim that United States forest product companies have not put enough effort into marketing forest products to Central America. Forests in El Salvador, Panama, and Costa Rica are limiting harvests and the industry lacks support from the government, reducing the amount of raw material and production. Inconsistencies between Appalachian and Central American wood products industries (e.g., dimensions) act as a barrier to the efficient exchange of wood products. The best market strategies for Appalachian forest products companies to increase sales into Central America are: partner with local wholesalers, offer higher value-added products, and maintain similar pricing with competition. An outside source of wood is needed to meet the needs of growing regional infrastructure.
CELL 256: Role of dispersion and polar interactions in the adsorption of cellulases onto lignin
Roman, Maren; Jiang, Feng; Chen, Qian; Esker, Alan R. (2018-03)
Residual lignin in pretreated biomass hinders its enzymatic hydrolysis. Nonionic surfactants are known to have beneficial effects on the enzymatic hydrolysis of lignocellulosic biomass but their mechanisms of action at the molecular level are incompletely understood. This study investigates the effect of a nonionic surfactant, Tween 80, on the adsorption of cellulases onto model lignin substrates. Lignin substrates were prepared by spin coating of flat substrates with three different types of lignin: organosolv lignin, kraft lignin, and milled wood lignin. Tween 80 and cellulase adsorption onto the lignin substrates was analyzed with a quartz crystal microbalance with dissipation monitoring. Supporting experiments of Tween 80 and cellulase adsorption onto self-assembled monolayers with lignin-related functional groups provided critical insights into the role of polar and dispersive functional groups in lignin on cellulase adsorption and the effect of Tween 80 on the process.
Cellulose derivatives with a low degree of substitution
(United States Patent and Trademark Office, 1996-06-04)
The invention is directed to the formation of cellulose derivatives using homogenous phase reaction conditions. Cellulose is dissolved using DMAc/LiCl and a reagent system is added to promote the acylation of an appropriate acid anhydride or free carboxylic acid. One reagent system includes N,N-dicyclohexylcarbodiimide (DCC) and 4-pyrrolidinopyridine (PP). Another reagent system includes p-toluene sulfonyl chloride (TsCl) and pyridine (Py).
Changes in the Chemical Composition and Decay Resistance of Thermally-Modified Hevea brasiliensis Wood
Durgante Severo, Elias Taylor; Calonego, Fred Willians; Sansigolo, Claudio Angeli; Bond, Brian H. (PLOS, 2016-03-17)
In this study the effect of thermal treatment on the equilibrium moisture content, chemical composition and biological resistance to decay fungi of juvenile and mature Hevea brasiliensis wood (rubber wood) was evaluated. Samples were taken from a 53-year-old rubber wood plantation located in Tabapuã, Sao Paulo, Brazil. The samples were thermally-modified at 180°C, 200°C and 220°C. Results indicate that the thermal modification caused: (1) a significant increase in the extractive content and proportional increase in the lignin content at 220°C; (2) a significant decrease in the equilibrium moisture content, holocelluloses, arabinose, galactose and xylose content, but no change in glucose content; and (3) a significant increase in wood decay resistance against both Pycnoporus sanguineus (L.) Murrill and Gloeophyllum trabeum (Pers.) Murrill decay fungi. The greatest decay resistance was achieved from treatment at 220°C which resulted in a change in wood decay resistance class from moderately resistant to resistant. Finally, this study also demonstrated that the influence of thermal treatment in mature wood was lower than in juvenile wood.
Circular business models in high value manufacturing: Five industry cases to bridge theory and practice
Okorie, Okechukwu; Charnley, Fiona; Russell, Jennifer D.; Tiwari, Ashutosh; Moreno, Mariale (2021-01-12)
The transition to a circular economy (CE) requires companies to evaluate their resource flows, supply chains, and business models and to question the ways in which value is created. In the high value manufacturing (HVM) sector, this evaluation is critical, as HVM enables value in nonconventional forms, beyond profit, including unique production processes, brand recognition, rapid delivery times, and highly customized services. We investigate the role of value, cost, and other factors of influence in the selection of a circular business model (CBM) for HVM. Explored through five case studies using a qualitative evaluation of circularity, we then contribute to the emerging field of CBMs by modifying the CBM canvas that can capture the nontraditional value, traditional value, cost, and other influencing factors enabled via CBM adoption in HVM. Finally, the important role of digital technologies for incentivizing and enabling CBM adoption, is clarified.
¿Cómo integrar la estrategia de una empresa con su sistema de gestión de calidad?
Quesada, Henry Jose; Aguilar Rodriguez, Silvia; Espinoza, Carlos (Instituto Tecnologico De Costa Rica, 2006-06-01)
Se realizó una investigación con el fin de contar con una guía que permita desarrollar sistemas de gestión de calidad integrados con la estrategia, que no solo evalúen la capacidad de la empresa de ofrecer productos / servicios con el nivel de calidad requerido, sino que también midan la eficacia del sistema de gestión de calidad en apoyar a la empresa a alcanzar su visión. Esto por cuanto lo que se pudo determinar de la situación actual es que se deja a la mera percepción de las gerencias el evaluar la eficacia del sistema de gestión de salidad. La principal conclusión de esta investigación es que los sistemas de gestión de calidad deben dejar de ser operativos y deben pasar a un plano más gerencial, para proveer información que permita tomar decisiones sobre la orientación estratégica de la empresa. Finalmente, se validó la metodología en una empresa y se logró comprobar que la metodología es aplicable, pues permite definir métricas que integren la estrategia de la empresa con su sistema de gestión de calidad y de este modo se facilita la evaluación de la eficacia de dicho sistema.
Comparison of the Economic Feasibility between Conventional and Vacuum Drying for 4/4 Red Oak
Brenes-Angulo, Oxana; Bond, Brian H.; Kline, D. Earl; Quesada, Henry Jose (Forest Products Society, 2017-01-01)
Vacuum drying of wood is a method to reduce drying time and inventory; however, there is limited information regarding the economic feasibility for vacuum drying 4/4 red oak compared with traditional drying methods. The benefits of this technology, mainly dramatically reduced drying times and higher flexibility, must be weighed against the higher initial capital investment. The goal of this project was to compare the economic feasibility, using capital budgeting techniques, of conventional drying and vacuum drying for 4/4 red oak lumber. The analysis was conducted for two actual flooring manufacturers. Conventional drying for this analysis was considered to be air-drying plus kiln drying, which is commonly done with red oak. The vacuum technology considered used hot platens for heating the wood. Species, thickness, drying methods, and lumber demand compared, both drying methods (conventional and vacuum drying) were determined to be economically feasible. However, vacuum drying had a slightly higher net present value, cost–benefit ratio, and sensitivity analysis than conventional drying, making it a slightly better investment for drying 4/4 red oak. The initial tied-up inventory and its respective cost in the conventional drying scenario represents an opportunity cost that can be recovered using vacuum drying. This recovered cost can result in freed capital that can be invested elsewhere to increase competitiveness.
Competitive Adsorption of Cadmium(II) and Mercury(II) Ions from Aqueous Solutions by Activated Carbon from Xanthoceras sorbifolia Bunge Hull
Zhang, Xiaotao; Hao, Yinan; Wang, Ximing; Chen, Zhangjing; Li, Chun (Hindawi, 2016-12-19)
This paper presents low-cost and recyclable activated carbon (XLAC) derived from Xanthoceras sorbifolia Bunge hull for high-efficiency adsorption of Cd(II) and Hg(II) ions in industrial wastewater. XLAC was prepared through H3PO4 activation and was characterized using N2 adsorption-desorption, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), and Fourier transform infrared (FTIR) spectroscopy. In single-metal-system adsorption experiments, the maximum adsorption capacities for Cd(II) and Hg(II) obtained under different experimental conditions were 388.7 and 235.6 mg·g−1, respectively. All adsorption equilibrium data fit perfectly with the Langmuir isotherm model. In a binary metal system, competitive studies demonstrated that the presence of Cd(II) significantly decreased the adsorption of Hg(II), but the adsorption of Cd(II) showed a little change in the presence of Hg(II). In addition, XLAC can be regenerated with a 0.01 mol·L−1 HNO3 solution and reused at least four times. The FTIR spectra revealed that a chemical interaction occurs between functional groups containing lone electron pairs in XLAC and metal ions. Overall, these results suggest that XLAC may be suitable as an adsorbent for heavy metal removal from wastewater streams.
Competitive Strategies for International Marketing of Hardwood Products Based on the Mining of Open Questionnaire Data
Arias, Edgar; Quesada, Henry Jose; Smith, Robert L. (2020-11)
International markets for U.S. forest products continue to make a significant contribution to the national economy; sustaining growth in production and job creation as demand from domestic markets is still yet to match that observed during the early 2000s. In this context, industry, government, and academia remain focused on procuring better market shares in foreign markets. The goal of this research is to help hardwood mills to improve their understanding of the needs of potential clients abroad and thus helping them to develop a competitive advantage. An exploratory study based on text mining of questionnaire data was conducted following a competitive criteria-based model on the major foreign markets for U.S. hardwood products. From a sample of buyers attending trade shows in Asia and Europe, this work has identified a series of factors for manufacturers to consider in future export ventures. It was determined that price and quality play multiple roles in developing a competitive advantage. Color-consistency and an adequate stock of the right mix of species are considered minimum requirements to compete in those markets. In contrast, certain time-compression dimensions are perceived as opportunities to add value and, therefore, to stay ahead of the competition.
Compositional Characterization of Different Industrial White and Red Grape Pomaces in Virginia and the Potential Valorization of the Major Components
Jin, Qing; O’Hair, Joshua; Stewart, Amanda C.; O'Keefe, Sean F.; Neilson, Andrew P.; Kim, Young Teck; McGuire, Megan N.; Lee, Andrew H.; Wilder, Geoffrey; Huang, Haibo (MDPI, 2019-12-11)
To better evaluate potential uses for grape pomace (GP) waste, a comprehensive chemical composition analysis of GP in Virginia was conducted. Eight commercial white and red pomace samples (cv. Viognier, Vidal Blanc, Niagara, Petit Manseng, Petit Verdot, Merlot, Cabernet Franc, and Chambourcin) obtained from different wineries in Virginia, USA were used. For extractives, GPs contained 2.89%–4.66% titratable acids, 4.32%–6.60% ash, 4.62%–12.5% lipids with linoleic acid being the predominant (59.0%–70.9%) fatty acid, 10.4–64.8 g total phenolic content (gallic acid equivalents)/kg GP, 2.09–53.3 g glucose/kg GP, 3.79–52.9 g fructose/kg GP, and trace sucrose. As for non-extractives, GPs contained 25.2%–44.5% lignin, 8.04%–12.7% glucan, 4.42%–7.05% xylan, and trace amounts of galactan, arabinan, and mannan (less than 3% in total). Potential usages of these components were further examined to provide information on better valorization of GP. Considering the valuable extractives (e.g., polyphenols and oil) and non-extractives (e.g., lignin), designing a biorefinery process aiming at fully recover and/or utilize these components is of future significance.
Cytotoxicity and Cellular Uptake of Cellulose Nanocrystals
Dong, Shuping; Hirani, Anjali A.; Colacino, Katelyn R.; Lee, Yong Woo; Roman, Maren (2012-09-21)
There is growing evidence that filamentous nanoparticles offer advantages over spherical ones in drug delivery applications. The purpose of this study was to assess the potential of rod-like, plant-derived cellulose nanocrystals (CNCs) for nanomedical uses. Besides a nonspherical morphology, their facile bioconjugation, surface hydrophilicity and small size render CNCs promising drug carriers. The cytotoxicity of CNCs against nine different cell lines (HBMEC, bEnd.3, RAW 264.7, MCF-10A, MDA-MB-231, MDA-MB-468, KB, PC-3 and C6) was determined by MTT and LDH assay. CNCs showed no cytotoxic effects against any of these cell lines in the concentration range and exposure time studied (0–50 µg/mL and 48 h, respectively). Cellular uptake of fluorescein-50 - isothiocyanate-labeled CNCs by these cell lines, quantified with a fluorescence microplate reader, was minimal. The lack of cytotoxicity and the low nonspecific cellular uptake support our hypothesis that CNCs are good candidates for nanomedical applications.
Development of a Friction-Driven Finite Element Model to Simulate the Load Bridging Effect of Unit Loads Stored in Warehouse Racks
Molina, Eduardo; Horvath, Laszlo; West, Robert L. (MDPI, 2021-03-29)
Current pallet design methodology frequently underestimates the load capacity of the pallet by assuming the payload is uniformly distributed and flexible. By considering the effect of payload characteristics and their interactions during pallet design, the structure of the pallets can be optimized, and raw material consumption reduced. The objective of this study was to develop and validate a finite element model capable of simulating the bending of a generic pallet while supporting a payload made of corrugated boxes and stored on a warehouse load beam rack. The model was generalized in order to maximize its applicability in unit load design. Using a two-dimensional, nonlinear, implicit dynamic model, it allowed for the evaluation of the effect of different payload configurations on the pallet bending response. The model accurately predicted the deflection of the pallet segment and the movement of the packages for a unit load segment with three or four columns of boxes supported in a warehouse rack support. Further refinement of the model would be required to predict the behavior of unit loads carrying larger boxes. The model presented provides an efficient solution to the study of the affecting factors to ultimately optimize pallet design. Such a model has not been previously developed. The model successfully acts as a tool to study and predict the load bridging performance of unit loads requiring only widely available input data, therefore providing a general solution.
The effect of residual lignin on the rheological properties of cellulose nanofibril suspensions
Iglesias, Maria C.; Shivyari, Niloofar; Norris, Ann; Martin-Sampedro, Raquel; Eugenio, M. E.; Lahtinen, Panu; Auad, Maria L.; Elder, Thomas; Jiang, Zhihua; Frazier, Charles E.; Peresin, Maria S. (2020-10-10)
Although the removal of lignin and hemicelluloses from cellulose pulp to produce fully bleached cellulose nanofibrils (B-CNF) is the most common practice, the presence of residual lignin and hemicelluloses in raw materials for the production of lignin containing cellulose nanofibrils (LCNFs) holds several advantages. In this work, we investigated the effect of residual lignin inEucalyptus globuluscellulose fibers on the properties of the resulting LCNFs. The stability of the colloidal suspensions was assessed by zeta-potential values and charge density analyses. Morphology of the CNFs was studied using scanning electron microscopy and atomic force microscopy. Fibril diameter and diameter distributions for CNFs with different levels of residual lignin showed a decrease on fiber diameter as the lignin content increases. Differences in the chemical composition of the CNFs was evidenced as indicated in the Fourier-transform infrared spectroscopy spectra, particularly in fingerprint region. Thermal behavior of the CNFs was not altered by the presence of lignin, as indicated by thermogravimetric analysis. Finally, the rheological behavior of the samples was evaluated observing a gel-like behavior as well as an increase of the viscosity in LCNFs with higher lignin contents.
Effects of Thermo-Hydro-Mechanical Treatments on Various Physical and Mechanical Properties of Poplar (Populus) Wood
Shao, Yali; Li, Lili; Chen, Zhangjing; Wang, Sunguo; Wang, Ximing (2020-11)
Poplar (Populus) wood was subjected in this work to thermo-hydro-mechanical treatment. The influence of the treatment parameters on the physical and mechanical properties were investigated. The wood samples were densified under three compression ratios (0%, 30%, and 50%), and thermally treated at three temperatures (180 degrees C, 200 degrees C, and 220 degrees C), at three thermal treatment durations (3 h, 4 h, and 5 h). The density, modulus of elasticity, modulus of rupture, radial hardness, and thickness swelling were measured. The results showed that the densities of the samples increased by 36.6% to 49.7%. As the compression rate increased, the temperature, duration, modulus of elasticity, modulus of rupture, and hardness increased. However, the dimensions of the densified samples were less stable. Compared to the densified samples, the maximum thickness swelling could be reduced by 74% (from 29.7% to 7.8%) when subjected to a thermal treatment at 220 degrees C for 3 h.

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