Research Articles

The moisture dependence of different mechanical properties of bamboo has not been fully understood. In this work, the longitudinal tensile modulus, bending modulus, and compressive and shearing strength parallel to the grain were determined for bamboo of ages 0.5, 1.5, 2.5, and 4.5 years under different moisture contents (MC) to elucidate the sensitivity of different mechanical properties of bamboo to MC change. The results showed that the four mechanical properties of bamboo respond differently to MC changes. Compressive and shearing strength parallel to the grain were most sensitive to MC changes, followed by longitudinal tensile modulus, then bending modulus. This can be partially explained by the different responses of the three main components in the plant cell wall to MC change. For tensile modulus and bending modulus, the effect of bamboo age on the sensitivity to MC change was insignificant, while young bamboo (0.5 years old) was more sensitive to MC changes for shear strength and less sensitive for compression strength than older bamboo.

Rhizomucor tauricus, an industrial fungus, was immobilized in sodium alginate and used as adsorbent for the removal of nickel from aqueous solutions. The biosorption capacity of Ni(II) was found to be 394 mg/g of immobilized biomass. It was observed that an increase in pH from 3 to 6 increased the percent adsorption, and an increase in liquid-to-solid ratio from 2 to 10 increased the metal uptake. The percent adsorption was increased when increasing the initial metal concentration from 25 to 100 mg/L. The equilibrium biosorption data was evaluated by Langmuir, Freundlich, and Langmuir-Freundlich (L-R) isotherm models, and was best described by the Langmuir and Freundlich isotherms. FTIR analysis revealed that –NH (bending), C–H (stretching), C=O (stretching), and –OH functional groups were mainly responsible for Ni(II) biosorption. Thus, this study demonstrated that the immobilized Rhizomucor tauricus biomass could be used as an adsorbent for the treatment of Ni(II) from aqueous solution.

During the most recent decades the U.S. wood products and furniture manufacturing industries have been greatly affected by economic cycles, rising production and transportation costs, changing buyer habits, and, arguably most powerfully, increasing global competition. However, theories exist stating that the use of management systems, such as Lean, allows companies to be more successful despite operating in a more challenging environment. To assess Virginia’s wood products and furniture manufacturing industry’s Lean awareness and Lean implementation efforts, a census survey was conducted. Findings indicate that a majority of Virginia’s wood products and furniture manufacturing industry have heard about Lean (72 percent), but a relatively low number of respondents are aware of the details of Lean. Forty-seven percent of respondents indicated to have implemented Lean. However, the extent of Lean implementation varied widely, with a majority having implemented less than half of all 29 Lean elements inquired about in this survey. Business results from implementing Lean and the need for external Lean implementation support are presented in the second manuscript of this two-manuscript series.

This two-part publication about Lean practices by Viriginia’s wood products and furniture manufacturing industries reports results from researching the awareness, the implementation status, the business results, and the need for external implementation support of Virginian companies. This second manuscript focuses on business results and the need for external implementation support. Except for “sales per employee,” where less than half of respondents reported an improvement due to the implementation of Lean in their operation, a majority of respondents indicated improved business results for “lead time,” “on-time delivery,” “inventory turnover,” and “cost per unit.” With respect to the need for external Lean implementation support, only 23 percent of respondents answered in the affirmative. “Training management,” “training shop floor employees,” and “implementing [Lean] with extensive employee involvement” were, with 67, 58, and 48 percent frequencies, the most often named forms of Lean implementation support requested. Results from this study seem to indicate an opportunity to support the well-being of Virginia’s wood products and furniture manufacturing industries through improved communication of the benefits of Lean and offering specific types of training to companies.

Activated carbon was prepared from sugarcane bagasse with phosphoric acid activation by a mechanochemical process. The effects of milling time on adsorption properties and pore structure of activated carbon were evaluated. The results showed that phosphoric acid activation was assisted by the mechanochemical process, which can reduce the processing time and improve the adsorption performance of the prepared activated carbon. The iodine number, the methylene blue adsorption value, and the specific surface area of the prepared activated carbons were improved from 647.94 mg/g, 150 mg/g and 1075.21 m2/g to 889.37 mg/g, 177 mg/g, and 1254.52 m2/g, respectively. Compared with conventional phosphoric acid activation, the activated carbon produced by the mechanochemical process achieved the advantages of shorter processing time, greater adsorption capacity, and higher adsorbed amounts of iodine, methylene blue, and nitrogen.

Heat treatment can be used to improve the physical properties and durability of wood. The results achieved by heat treatment can be affected significantly by various factors. Juvenile wood and mature wood from the same trunk have different properties, and the effects of heat treatment on their physical properties have not been well defined. Thus, a study to determine the differences in the physical properties of juvenile wood and mature wood of E. grandis after heat treatment was conducted. Samples of both types of wood were treated at temperatures of 120, 150, and 180 ºC for durations of 4, 6, and 8 h. The results showed that the physical properties of juvenile and mature wood, e.g., swelling, moisture content, and fiber saturation point, did not decrease to the same extent. Mass loss of mature wood was higher than that of juvenile wood. Generally, percentage decreases of volumetric swelling, moisture content, and fiber saturation point of juvenile wood were more affected than those of mature wood.

In this work, the effect of oil heat treatment (OHT) on the swelling properties and changes in the rate of moisture uptake of poplar wood (Populus × euramericana cv. Pannónia) were investigated. Eighteen different treatments (combinations of three vegetable oils, two temperatures, and three durations) were studied. The results showed that OHT decreases the equilibrium moisture content (EMC) and the swelling of poplar wood. The degree of swelling and the EMC are influenced by both the duration and temperature of treatment. With an increase in duration and temperature, the EMC decreased. Consequently, the anti-swelling efficiency (ASE) increased. OHT wood adsorbs less moisture than natural wood, but it reaches a maximum – EMC at the momentary climate – at the same time under all the investigated treatments. The moisture uptake is fastest in the beginning and thereafter it slows significantly. Decreasing the moisture uptake by OHT wood is due to the decreasing of its water storage capacity.

Tannin-boron wood preservatives were investigated for their resistance against outdoor agents. This work focused on the analysis of the causes that affect the durability of the tannin-hexamine-treated samples. In particular, dimensional stability, resistance to leaching, and resistance to biological agents were investigated. The combined effect of deterioration agents was evaluated by subjecting the treated samples to simulated and natural weathering tests. The study of the appearance and of the color components (L*, a*, and b*) according to CIELAB space of the exposed samples was monitored to assess the efficacy of the tannin-boron formulations for outdoor applications. Significant resistance against the action of water (EN 84, ENV 1250-2) and insects (EN 47) has been demonstrated in specific tests. Conversely, the continuous stress due to artificial and natural weathering deteriorates the color and the visible features of the treated specimens. The combined effect of moisture modifications, solar exposition, and leaching cycles damages the structure of the tannin-based polymeric network and subsequently it negatively affects its preservation properties.

Pretreatment of sawdust using a combination of sodium hydroxide (NaOH) and monochloroacetic acid (MCA) was investigated for the formation of reducing sugars. Optimum conditions for the pretreatment process were determined by the amount of reducing sugars formed during the enzymatic hydrolysis of the pretreated substrate. It was found that mercerization by NaOH played an important role in increasing the degree of substitution (DS) and that the maximum solubility was achieved during the etherification by MCA. A maximum amount of 34.2% lignin was removed in the process. As the DS of the substrate was increased, the efficiency of the hydrolysis process increased, leading to the higher yield of reducing sugars. The optimum operating conditions for the pretreatment process were determined to be 75 ºC at 90 rpm for 4 hours (2 hours for mercerization plus 2 hours for etherification). Under these operating conditions, with 1% (w/v) NaOH and 2% (w/w) MCA loading, a maximum DS of 0.2 and a solubility of 10.3% was attained. At 75 ºC and after 48 hours of the hydrolysis process, cellulases from Aspergillus niger resulted in the production of 2.88 g/L of glucose with a yield of 62.72% reducing sugars. X-ray diffraction (XRD) revealed reduced crystallinity of the sawdust and Scanning Electron Microscopy (SEM) showed distortion of the structure after pretreatment.

In this work, the physical and mechanical properties of bleached Eucalyptus pulp reinforced with nanofibrillated cellulose (NFC) are compared with those of traditional beaten pulp used in the making of writing/printing and offset printing papers. For this purpose, three different types of hardwood slurries were prepared: beaten pulps, unbeaten pulps reinforced with NFC, and slightly beaten pulps also reinforced with NFC. Physical and mechanical tests were performed on handsheets from these different slurries. The results showed that adding NFC to unbeaten pulps results in physical and mechanical properties similar to those in pulps used for printing/writing papers. Nevertheless, the best results were obtained in slurries previously beaten at slight conditions and subsequently reinforced with NFC. These results demonstrate that the addition of NFC allows a reduction in beating intensity without decreasing the desired mechanical properties for this specific purpose.