Morphological, physical, thermal, and mechanical properties of nanocrystalline cellulose (NCC) were determined. Moisture content as well as oil absorption were also studied. The NCC was obtained from sulfuric acid hydrolysis of wood pulp. Transmission electron microscopy showed that NCC has a diameter of 10 nm and a length of 150 nm. Fourier transform–Raman spectroscopy and x-ray diffraction experiments both showed that NCC has a very high degree of crystallinity. Using an Abbe refractometer, the average refractive index of the NCC in different solvents was determined to be 1.499. Hardness and elastic modulus of the homogeneous, translucent NCC films were determined by nanoindentation technique. Oil absorption and moisture content were related to the particle size.
Fast-growing poplar (Populus ×euramericana NL-95) has been extensively cultivated in China. However, because of its poor quality, poplar wood is commonly used only in the manufacture of low-grade wood products. If the wood could be improved by postharvest treatment, it would be more useful and more saleable. Such modification is possible. Our team has developed a protocol to modify fast-growing poplar by impregnating poplar wood with styrene (ST) and glycidyl methacrylate (GMA); this treatment is followed by in situ polymerization by means of thermal treatment. Experimental results show that the treated wood absorbed only one-fifth of the water absorbed by untreated wood when both were submerged in water for 1 week. The treated wood was also two times as dimensionally stable. When treated and untreated wood specimens were exposed to termites and to the fungi that cause dry rot, the treated wood was 9.3 times as resistant to termites and 3.8 times as resistant to fungi. Specimens of treated wood were examined using Fourier transform infrared spectroscopy, which showed that a grafting reaction and copolymerization had occurred, bonding the hydroxyl groups of the wood cell walls to the GMA and ST. Scanning electron microscope observation of the treated wood showed that the cell lumens had been filled with polymers and that the interfaces between wood cell walls and polymer were hard to distinguish.
Part I of this article described the treatment of specimens of fast-growing poplar (Populus ×euramericana NL-95) with styrene (ST) and glycidyl methacrylate (GMA) monomers. It detailed the results of tests for water absorption, dimensional stability, and termite and fungus resistance. This part continues the previous work. It examines the static and dynamic mechanical properties, as well as the thermal stability, of polymer-infused wood (PIW). Static mechanical properties of PIWs were assessed in terms of bending strength, compressive strength, and Brinell hardness. Our results showed that, as a result of the treatment, these properties were significantly increased. Moreover, the PIW treated with GMA-ST showed greater mechanical strength than PIW treated with ST alone. We believe that this is due to the formation of cross-linked bonds between the GMA-ST and the hydroxyl groups of the wood's cell walls. Dynamic mechanical analysis (DMA) demonstrated that, at normal temperatures, storage modulus E′ and molecular structure stability of wood were significantly enhanced by the treatment. However the loss factor (tan δ) of PIWs was sharply elevated at a higher temperature range. Finally, thermogravimetric analysis (TGA) indicated that the thermal stability of wood was greatly improved by the treatment; the wood treated with GMA-ST showed slightly higher thermal stability than the wood treated with ST alone.
Experimental measurements of thermal conductivity of wood were performed using the heat flow meter and transient plane source technique. The specimens were prepared from five species of both softwoods and hardwoods widely available and used in China, with a wide range of density and moisture content. The transverse thermal conductivity of ovendry specimens is presented as a function of density and temperature up to 90°C and is compared with that along the grain direction for two select species. The influence of moisture content up to 23 percent, which is below the typical fiber saturation point of wood, on the transverse thermal conductivity is presented as well. It is shown that the transverse thermal conductivity of wood increases with density, temperature, and moisture content. Linear correlating equations are proposed in terms of these factors.
A cost-effective estimation of wood quality of hardwood green logs is needed. The purposes of this study were to investigate and compare two nondestructive acoustic methods to predict the wood quality of green logs from a poplar I-72 (Populus ×euramericana cv. I-72/58 “San Martino”) plantation. After log measurements, small clear wood specimens were cut and air dried to 12 percent moisture content. The static bending modulus of elasticity (MOE) of small clear wood specimens was about 15 and 20 percent greater than the dynamic MOE of green logs based on resonance vibration (Efr) and stress wave (Esw). However, good correlations (R) between Efr and Esw of logs and bending MOE of 0.806 and 0.848 (P <0.001), respectively, were observed. Significant correlations were also found between the Efr and Esw of logs and the modulus of rupture and compressive strength parallel to grain (σc) of small clear wood specimens (P < 0.001). The results indicate that both acoustic techniques were effective predictors of wood quality, although the stress wave method was found to be more accurate and reliable than the resonance vibration method. The longitudinal changes of strength properties with tree height could be tracked by these two methods.
Small hardwood chips, known as pellet chips, were characterized and combusted in two different pellet burners, installed in a residential boiler specially designed for pellet combustion. The average particle mass was about 10 percent of the mass of an 8-mm pellet, with a similar surface-to-volume ratio. The bulk density of pellet chips was 160 to 170 kg m−3 at 10 percent moisture content (about 25% to 35% of 8-mm pellet bulk densities). The combustion performance was good, with average O2 and CO values (by volume) at 17.6 percent (SD, 0.6%) and 200 ppm (SD, 210 ppm), respectively, for the bottom-fed burner and 14.2 percent (SD, 1.1%) and 330 ppm (SD, 93 ppm), respectively, for the top-fed burner. Thus the study indicates that pellet chips produced with commercially available equipment can be used in ordinary pellet combustors, provided that the fuel feeding rates are increased and the moisture content well below 20 percent. More accurate market assessments will require the investigation of the performance of different types of combustion equipment with fuels of different qualities.
Wood fiber–plastic composite materials, a relatively new material, are finding applications mainly in the US residential and commercial construction markets. Thus, the volume of material produced and used is steadily increasing while the range of applications keeps expanding. So far, attention has been paid mainly to primary production processes of wood fiber–plastic materials, while secondary manufacturing processes have attracted less attention. However, with the broadening applications of such materials and their increasing use, secondary manufacturing processes for wood fiber–plastic materials are gaining importance. This study investigated the performance of five commercially available wood fiber–plastic composite materials and solid wood (eastern white pine) with respect to tool wear and resulting material surface roughness. Large performance differences between different wood fiber–plastic composite materials and between solid wood and wood fiber–plastic composite materials with respect to tool wear were found. Solid wood did wear the exchangeable tungsten carbide knives with a standard cobalt binder and ultrafine carbide grain knives used for the tests 12 to 42 times less than the wood fiber–plastic composite materials. However, some wood fiber–plastic materials were found to have a smoother surface than solid wood after 38.2 m of cutting. As this research showed, different wood fiber–plastic composite formulations behave differently when subjected to secondary manufacturing processes, and more research is needed to better understand the underlying causes for those observations.
The objective of this study was to investigate the effects of material type, screw diameter, and screw length on ultimate failure load and stiffness of four-sided furniture cabinets. In total, 81 four-sided test cabinets were constructed in 1/1 dimensions. Assembly of cabinets was done using nine different sizes of screws ranging from 3.5 by 40 mm to 5 by 50 mm. Panel materials were 18-mm-thick particleboard (PB) and 16- and 18-mm-thick medium-density fiberboard (MDF1, MDF2). Cabinets were anchored at two points located underneath the top panel and tested under static load. Loading procedures of the American National Standards Institute/Kitchen Cabinet Manufacturers Association were followed during the static tests. Test results showed that 18- and 16-mm MDF cabinets yielded higher failure loads and stiffness values compared with the 18-mm PB cabinets. Test results also indicated that increasing either screw diameter or screw length tended to have a positive effect on the failure load and stiffness values. The strongest and most rigid four-sided cabinets were obtained with 4-mm-diameter and 50-mm-long screws if the construction panel material was 18-mm-thick MDF, 5-mm-diameter and 45-mm-long screws if the construction panel material was 16-mm-thick MDF, and 5-mm-diameter and 50-mm-long screws if the construction panel material was 18-mm-thick PB.
Information technology (IT) has advanced at a rapid rate during the past three decades, and when used well, IT can bestow a competitive advantage in the modern economy. This article reviews key studies on IT adoption in US and Canadian forest products industries, summarizes their common findings, gives insights on these commonalities, and recommends future areas of research. The most frequent conclusion of these studies was that most forest products firms used only basic ITs. IT adoption rates were often found to be positively correlated with firm size and proportion of sales from exports. Most firms invested less than $10,000 in IT, which was not enough to develop sophisticated IT. Firms often perceived the largest benefits of IT to be promotional in nature, while cost-cutting operational benefits were usually ignored. Overall, with the exception of the pulp and paper industry, a cautious attitude toward IT adoption was observed. The low IT adoption by this sector could be attributed to several factors, such as being a highly production-oriented industry with few IT savvy personnel.
Mold growth on dried Norway spruce and Scots pine sapwood boards was investigated in an accelerated outdoor field test for 96 days. The boards were dried using three different methods of stacking: single stacking, double stacking with the sapwood sides in each pair facing toward each other, and double stacking with sapwood sides facing outward. Drying was performed at three temperatures: 25°C, corresponding to air drying, and kiln drying at 70°C and 110°C. The degree of mold growth was visually assessed on both sides of each board. On average, pine boards showed a higher level of mold growth than the spruce boards. The highest average level of mold growth was found on the boards kiln dried at 70°C, whereas the air-dried boards and the boards kiln dried at 110°C showed considerably less mold growth. Stacking the boards during drying had a large impact on mold susceptibility of the sapwood. This study confirmed that, during the drying process, it is possible to direct the migration of nutrients in sapwood toward one chosen side of each board by double stacking; the opposite side leaches out, which has a great impact on surface mold growth. Chemical analyses of monosaccharide sugar gradients beneath the boards' surfaces confirmed the results.
Pyrolytic liquid (bio-oil), produced by pyrolyzing the shell of the palm fruit, was characterized, and its preservative properties were examined using drywood termites (Cryptotermes spp.) and blue stain fungi (Ceratocystis spp.). The yield from shell bio-oil production ranged from 35 to 37 percent relative to the mass of the raw material. The shell bio-oil had the following properties: specific gravity (ranging from 1.0365 to 1.0431), refractive index (ranging from 1.3594 to 1.3613), wood absorption level (ranging from 0.0088 to 0.0625 g/cm3), and retention (ranging from 0.0022 to 0.0141g/cm3). The shell bio-oil also had termicidal activity as shown by drywood termite mortalities: 25 percent between days 3 and 6, 50 percent between days 3 and 20, and 100 percent between days 5 and 49 in termite resilience tests. Using a fluorescence microscope, we demonstrated that the shell bio-oil–treated wood completely inhibited the growth of blue stain fungi on both pine (Pinus merkusii) and Sengon (Paraserianthes falcataria) wood.
Eastern white cedar (Thuja occidentalis L.) is a naturally durable wood species due to toxic compounds present in the heartwood. These compounds may serve as natural fungicides to protect nondurable wood products from biodegradation. This study was intended to improve the effectiveness of posttreating aspen oriented strand board (OSB) panels with white cedar heartwood extracts against mold and decay by co-applying a protective coating. The results showed that aspen OSB samples treated with the white cedar water-soluble heartwood extracts had little mold infection. No mold growth was detected on any samples that were dip treated with the extracts and then brushed with a coating. The decay test showed that most samples treated with both white cedar heartwood extracts and a coating had significantly less weight loss than untreated control samples. Using coating products alone also reduced mold and decay growth on OSB samples; however, adding cedar extracts to the treatment significantly improved the performance of one of the three coating products tested against mold and decay.