Treesearch

In this work, TEMPO cellulose nanofibril (TOCNF) laminates were fabricated using a layup method. Two different TOCNF layers were tested, a neat TOCNF and a TOCNF with polyvinyl alcohol (PVA) strengthening aid with four different epoxy formulations as interlayers for the laminates. Flexural testing showed a correlation between the presence of stronger layers (TOCNFs + PVA) in the laminate with a higher flexural strength, bending modulus, and work of failure. Different modes of fracture within the laminates occurred based on epoxy type. A stiffer epoxy generated a reduced mechanical response...

In this study, cellulose nanofbrils (CNFs) were modified by catalyzed lactic acid esterification in an aqueous medium with SnCl2 as a catalyst. Films were made from unmodified and lactic acid-modified CNF without a polymer matrix to evaluate the effectiveness of the modification. Ungrafted and lactic acid-grafted CNF was also compounded with poly(lactic acid) (PLA) to produce composites. Mechanical, water absorption, and barrier properties were evaluated for ungrafted CNF, lactic acid-grafted CNF films, and PLA/CNF composites to ascertain the effect of lactic acid modification on the...

Lignocellulose is a potential sustainable feedstock for the production of renewable biofuels and bioproducts. Nature embeds cellulose microfibrils within hemicelluloses and lignin, creating a robust nano-scale structure that is resistant to insects, pathogens, and harsh environments. This resilient lignocellulose structure, in turn, thwarts bioprocessing by preventing cellulolytic enzymes access to the cellulosic substrates and the subsequent release of sugars. Thus, bioprocessing requires a pretreatment process to disrupt the intimately bound polymers in the lignocellulose structure....

Cross-laminated timber (CLT) market demand is on the rise in the United States. Adequate protective measures have not been extensively studied. The objective of this study was to investigate the weathering performance of exterior wood coatings. We evaluated coated CLT sample surfaces based on visual appearance, color change (CIE*L*a*b), gloss changes, and water intrusion. From the five exterior wood coatings evaluated, only two showed adequate performance after twelve months field exposure. Based on visual ratings following the ASTM procedures, coating failure occurs more quickly in...

Herein, a one-pot strategy was used to prepare hydrophobic cellulose nanocrystals (CNCs) surface-modifed with tannic acid and octadecylamine. By this strategy, CNCs derived from wood (W-CNC) and tunicates (T-CNC) were modifed in situ and incorporated into a polylactic acid (PLA) matrix using two methods, without first drying the CNCs. Films of PLA-CNC nanocomposites were prepared both by solution casting and by wet compounding in a thermo-kinetic mixer, followed by melt extrusion. Various properties of these PLA nanocomposites were evaluated herein, along with an assessment of how these...

Manufacturing of building materials and construction of buildings make up 11% of the global greenhouse gas emission by sector. Mass timber construction has the potential to reduce greenhouse gas emissions by moving wood into buildings with designs that have traditionally been dominated by steel and concrete. The environmental impacts of mass timber buildings were compared against those of functionally equivalent conventional buildings. Three pairs of buildings were designed for the Pacifc Northwest, Northeast and Southeast regions in the United States to conform to mass timber building...

Petroleum-based polymers have served the packaging industry in numerous ways as films, pouches, rigid containers, foamed containers, and other components for food, medical, and other packaging applications. However, growing concerns about environmental impact, awareness of greenhouse gas emission and their adverse effects, increased oil prices, and disposal and landfill issues are forcing researchers and the industry to develop sustainable packaging. Biobased materials, those derived from biological sources rather than petroleum sources, are ideally suited to meet these new sustainability...

This work investigated the redispersion and setting behavior of highly loaded (∼ 18 wt.% solids in water) pastes of cellulose nanofibrils (CNFs) with carboxymethyl cellulose (CMC). A single-screw extruder was used to continuously process CNF + CMC pastes into cord. The adsorption of CMC onto the CNFs was assessed through zeta potential and titration which revealed a surface charge change of ∼ 61% from - 36.8 mV and 0.094 mmol/g COOH for pure CNF to -58.1 mV and 0.166 mmol/g COOH for CNF + CMC with a CMC degree of substitution of 0.9. Dried CNFs with adsorbed CMC was found to be fully...

For wood and forest products to reach their full potential as structural materials, experimental techniques are needed to measure mechanical properties across all length scales. Nanoindentation is uniquely suited to probe in situ mechanical properties of micrometer-scale features in forest products, such as individual wood cell wall layers and adhesive bondlines. However, wood science researchers most commonly employ traditional nanoindentation methods that were originally developed for testing hard, inorganic materials, such as metals and ceramics. These traditional methods assume that...

The AWPA E10 soil block test is one of the most often used methods to screen wood protectants against pure cultures of wood degrading fungi in North America. The test methodology was first developed in the early 1900s and has been adapted to evaluate a wide range of chemically treated, modified, and naturally durable woods and wood-based materials. The history and basic requirements of this fundamental test, along with good laboratory practices for optimum fungal strain performance, are discussed with practical considerations to ensure optimal and reproducible results.