Research Articles

Thermal modifications tend to darken wood color and enhance dimensional stability, erosion resistance, weather resistance, and product value. To investigate the chemical characteristics of VOCs influenced by the heat treatment process, air-dried poplar wood was heat-treated at four treatment temperatures (160,180, 200, and 220 °C) for 2 h. Near-infrared spectroscopy (NIR) was used to investigate the changes in sample hemicellulose, cellulose, and lignin composition. Acid-insoluble lignin and holocellulose were determined using wet chemistry methods. Volatile organic compounds of the poplar wood were analyzed for composition using gas chromatographic-mass spectroscopy coupled with dynamic headspace sampling. The results showed that the most significant volatiles in heat-treated poplar were aldehydes, which were the most abundant compound at 180 °C, in the furfural form. The amount of aromatic compounds and esters increased with increasing temperature. In addition, alcohol benzene extractives and acid-insoluble lignin increased, while holocellulose content decreased.

Lignocellulosic biomass is a potential raw material that can be used in the synthesis (manufacture) of porous carbon stuffs. The properties of such porous carbon products are affected by the species of the raw material and the manufacturing process, among other things. This paper scrutinizes the related characteristics of lignocellulosic raw materials that indicate potential for the production of porous carbon. Three species were used: pine (Pinusmerkusii) wood, mangium (Acacia mangium) wood, and candlenut (Aleuritesmoluccana) shells, representing softwoods, hardwoods, and non-wood stuffs, respectively. Analyses of their chemical compounds and proximate contents were carried out. Additionally, nano scale scrutiny of the lignocellulosic biomass was also conducted using the nano capable instruments, which consisted of SEM, EDS, XRD, FTIR, and DSC. Results revealed that pine wood had the most potential to produce porous carbon. Morphologically, pine wood afforded the best permeability, whereby at the structure of monoclinic cellulose crystals, there were cellulose-Ia structures, which contained less cellulose-Ib structures. Furthermore, pine wood exhibited greater volatile matter content, as confirmed through the FTIR, which greatly assisted the forming of porosity inside its corresponding carbon.

The applications of hybrid natural/synthetic reinforced polymer composites have been rapidly gaining market share in structural applications due to their remarkable characteristics and the fact that most of the components made of these materials are subjected to cyclic loading. Their fatigue properties have received a lot of attention because predicting their behavior is a challenge due to the effects of the synergies between the fibers. The purpose of this work is to characterize the tension, compression, and tensile-compression fatigue behavior of six layers of Kevlar hybridized with one layer of woven kenaf reinforced epoxy, at a 35% weight fraction. Fatigue tests were carried out and loaded cyclically at 60%, 70%, 80%, and 90% of their ultimate compressive stress. The results give a complete description for tensile and compression properties and could be used to predict fatigue-induced failure mechanisms.

The use of roundwood in structures has drawbacks that include tapering and lack of flatness, which can be overcome by making a longitudinal cut to flatten one side. The aim of this work was to compare the mechanical behavior of roundwood vs. roundwood with one flat face, comparing pieces of small-diameter roundwood from young trees of Pinus nigra Arnold. Half the samples were given a longitudinal cut. Specimens taken from these pieces were tested for bending and compression parallel to the grain to determine their modulus of elasticity and strength. The modulus of rupture by bending was 22% lower in roundwood with one flat face (59.0 MPa) than in roundwood (75.6 MPa). It has been observed that the smaller cross section in the roundwood with one flat face is not the only explanation for the decrease in the bending strength. In contrast, no significant differences were observed for the other three mechanical properties studied (compression strength parallel to the grain and modulus of elasticity in bending and compression).

In the mechanical pulping process, some process state and product quality variables are difficult to measure on-line. In this paper, soft sensors were used to estimate Canadian Standard Freeness (CSF) and outlet consistency (Cout) after the high consistency refining stage of the alkaline peroxide mechanical pulping (APMP) process. After the secondary variables for modeling that are readily available processed measurements in pre-treatment and the HC refining stage was selected, models based on the case-based reasoning (CBR) method were developed to estimate CSF and Cout. The ability of CBR soft sensors to predict CSF and Cout was tested using data collected from an APMP mill, and the results were satisfactory. Additionally, two typical soft sensor methods that back propagation network (BP) algorithms and support vector regression algorithms (SVR) were employed to predict CSF and Cout and evaluate the performance of the CBR soft sensor. As a result, the proposed soft sensor demonstrated a better performance than the BP method and can be regarded as of comparable quality to the SVR method.

Furfurylation of wood is of interest worldwide as an environmentally friendly modification process. It is widely assumed that low-molecular weight furfuryl alcohol (FA) can penetrate into wood cells and polymerize in-situ during the process, resulting in substantial improvement in the physical-mechanical properties and durability of wood. In this study, confocal laser scanning microscopy (CLSM) was used to visualize the microscopic distribution of polymerized FA resin in the Masson pine wood cavities, and a Nanoindenter was used to probe the mechanical properties of modified wood cells. The effects of catalysts (maleic anhydride and a mixed organic acid catalyst), FA concentration, curing time, and curing temperature on the nanomechanical properties of wood cell walls were investigated. An improvement in the indentation modulus and hardness of modified wood cells demonstrated indirectly but strongly that FA indeed penetrated wood cells during the modification process. Based on the results of the cell wall nanoindentation test, a combination of 50% furfuryl alcohol, 8 h curing time, and 95 °C curing temperature were proposed as the starting processing parameters for the development of a more practical and effective wood furfurylation process using a mixed organic acid catalyst.

Tar and char can be regarded as unwanted byproducts during the gasification process. In this study, three types of catalyst, i.e., biomass char (bio-char), nickel supported on biomass (Ni+bio-char), and nickel supported on bio-char (bio-char+Ni), were studied to compare the catalytic effects of different preparation methods on tar model compound removal. The structural characteristics of the three catalysts were also investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) methods. The results revealed that Ni+bio-char catalyst showed much higher activity for the reformation of toluene (C7H8) as a tar model compound than the other two catalysts. Toluene could be completely converted to small gas molecules at a conversion rate of 99.92% at 800 °C, and the maximum yield of gas was 432 mL/(mL C7H8). In particular, the H2 and CH4 yields were 339 and 85 mL/(mL C7H8) at 850 °C, respectively. An N2 absorption-desorption experiment demonstrated that the specific surface area of Ni+bio-char was 32.87 times that of bio-char and 8.39 times that of bio-char+Ni. Moreover, metallic nickel (Ni0) particles could be generated in the carbon matrix of Ni+bio-char catalyst. SEM analysis confirmed that the Ni+bio-char catalyst had a more porous structure. Nickel supported on biomass might be a promising catalyst for tar reformation because of its excellent catalytic activities.

A novel intermittent microwave-assisted carbonization method was developed to prepare bio-char (BWSC) from Durian wood sawdust (BWS). The BWS was further activated using a base-catalytic approach to produce a graphitic form of bio-carbon (BWSAC). A three factor, two-level central composite (CCD) experimental design was used to maximize Pb(II) ion removal from aqueous solution using BWSAC. Three independent variables (initial pH of solution (pH0) ranging from 2 to 8, initial metal ion concentration of Pb(II) cations (C0) ranging from 50 to 100 mg/L, and contact time (Ct) ranging from 10 to 300 min) were consecutively coded as x1, x2, and x3 at three levels (−1, 0 and 1) of the design matrix. The experimental conditions in terms of actual factors were determined to be x1 (pH0) = 5.86, x2 (C0) = 57.77 mg/L, and x3 (temperature) = 53.85 °C, and the resultant Pb(II) ion removal efficiency (y1) obtained was 92.73%, with a model desirability of 0.974. The change in physiochemical properties after carbonization as well as activation was observed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer, Emmett and Teller surface area analysis (BET), Thermogravimetric analysis (TGA), Ultimate analysis, and Fourier transform infrared spectroscopy (FTIR).

In the first stage of pulp bleaching, the quantity of added chemicals (ClO2 and/or Cl2) is commonly controlled by kappa factor, based on a kappa number online analyzer together with a compensated brightness control scheme as a feedback strategy. However, a kappa number analyzer is not always available, so the bleaching quality relies heavily on the chemical dosage set-point chosen by the operators. In this study, an improved model for the chlorination stage brightness optimization was proposed, based on brightness and residual chemicals before pulp enters the bleaching tower. Additionally, the experience of operators of (C95/D5) bleaching was employed in order to find an optimum chemical dosage set-point quickly. The golden section search algorithm (i.e., ‘0.618 method’) was used to find the optimum chemical dosage in this paper. After applying the proposed method in a pulp mill (C95/D5) bleaching stage, the chlorination stage brightness shifted from 62.9% ISO to the target value 60.7% ISO. Meanwhile, the standard deviation was reduced from 3.0 to 2.5.

Four fast-growing wood species were treated, including two hardwood species and two softwood species, with either furfurylation or acetylation for comparison and analysis. The properties of the resultant woods, including weight percent gain, bulking effect, leach rate, anti-swelling efficiency (ASE), and color changes, were compared comprehensively. The effects of wood species on modification efficiency were also evaluated by morphological analysis. The results indicated that the species of wood had little effect on successful acetylation, but that wood species with more open pits and loose and ordered structures were best suited for furfurylation. Both types of modification resulted in wood samples with more uniform colors than untreated samples. Furfurylation caused considerable color changes in all of the wood samples; acetylation resulted in wood samples slightly lighter in color (lower ΔE* values). The differences in ΔE* values among the four wood species were primarily due to the natural differences in the color of the woods.