Research Articles

Properties of unheated wood pellets were compared with those of torrefied wood pellets that had been heated to 270, 290, and 310 °C, with raw material taken from two different height levels of oil palm trunk (OPT). The gross calorific value, moisture content, ash content, volatile matter, fixed carbon, density, and weight loss were examined. Air drying or oven drying pretreatment was applied to the raw materials. The results showed that the heating values of samples increased when raw materials were torrefied, depending on the heat treatment temperature. The torrefied pellets were improved by as much as 66.4% in heating value compared with OPT pellet samples. The greatest improvement was found in torrefied pellet samples prepared at 310 °C, using air drying, and height levels of OPT between 0.3 to 1.5 m. The ash content of samples tended to increase when the torrefied temperature was increased, while the volatile matter value was reduced with high temperature. Based on the findings, OPT could be used as a raw material to produce value-added white and torrefied pellets as sustainable solid biofuel.

The goal of this work was to evaluate the fire-protection attributes after treating wood with crude acidic carbonate solutions from a natural source. A broader aim of this project was to find ways to increase the period of usefulness of wooden objects, thus contributing to a sustainable society. In this context, samples of scotch pine (Pinus sylvestris L.) wood with insecticides, fungi, insects+fungi, samples were taken, and sea mussel (Chamelea gallina) powders were impregnated at different solution concentrations (1%, 3%, 5%) according to ASTM D 1413 76 principles. Thermogravimetric analyses (TGA) were carried out. Although there were no significant changes in the initial temperature, the turning point temperature, or the final temperature values compared to the control groups, the percent weight loss and percent residue amount increased in all the impregnated group periods. Although there was little change in some groups due to the heterogeneity and anatomical structure of the wood, the percentage of residue decreased as the percentage of weight loss increased. Compared to the control sample, the second highest adhesion was observed in 3% cork pine wood (0.81%), weight loss (65.7%), and the amount of residue was 22.0%. Based on the TGA results, mussel shell was found to delay the combustion.

The large global production of particleboards creates an equal quantity of particleboard waste after completion of their service life. Given increasing demand for green products and government environmental policies, it is urgent to develop technologies to recycle these used composite panels into valuable raw materials. This study was conducted to recover particles from waste laminated particleboards using various thermo-hydrolytic treatments. The recovered particles were used as raw materials with different substitutions of fresh particles to manufacture particleboard panels. The performance of the resulting particleboards was evaluated in terms of their mechanical properties and formaldehyde emissions. The nitrogen content of the control and resulting particles were measured to determine the resin removal in recycled particles. The results suggested that different thermo-hydrolytic treatments did not have significant influence on particles size distribution. Approximately 65% of urea-formaldehyde resin was removed from the particleboards treated at 140 °C/20 min. Particles recycled at 140 °C/20 min were comparable to fresh particles in terms of mechanical properties and formaldehyde emissions, and 100% of the recycled particles were used in the manufacture of particleboard without an adverse impact on the board performance.

To improve fire-retardant performance of Japanese larch (Larix kaempferi) wood, this study analyzed the effect of pinholes made by laser incising and fire retardant (FR) coating on the surface of Japanese larch wood. Combustion properties such as peak heat release rate (PHRR) and total heat release (THR) of Japanese larch and Korean red pine (Pinus densiflora) wood without FRs showed similar tendencies. The comparison of the combustion properties on wood injected with an inorganic water-soluble FR under vacuum revealed that the PHRR and the THR of Korean red pine wood decreased by 37 and 62%, respectively. FR was injected into the Japanese larch specimens with pinholes on the surface and additionally coated with 5% sodium silicate and 35% potassium bromide. The results indicated a 16 to 25 and 19% reduction in PHRR and THR, respectively, compared to those without the FR. Despite the pinholes and FR coating, the FR employed in this study did not meet the standards set in Korea (THR of 8 MJ/m2). This study serves as a reference for future studies on the application of pressurized conditions and other surface treatments to improve the FR percent injection and performance of Japanese larch wood.

Methods to improve the physical properties of recycled paper can greatly enhance its potential applications, especially for packaging. This study aimed to understand the effect of refining, cationic starch addition, and cellulosic nanofibers (CNF) generated from old corrugated containers (OCC) addition with recycled OCC on tensile index (TI) and ring crush index (RCI). Linerboard from OCC made on an industrial paper machine was compared with the lab prepared handsheets, and the results indicated that the lab procedure including the refining step produced board reflective of the industrially made linerboard. CNF addition was observed to decrease the drainage rate of the unrefined OCC pulp stock but not significantly when the OCC pulp stock was refined to a freeness of 300 mL CSF. The results of a statistically designed experiment showed that cationic starch, refining, and the interaction between cationic starch and CNF were significant parameters that improve TI. Through experiments that measured the retention of the pulp stock, it was determined that CNF retention was only 44.8% without cationic starch and increased to 90.0% with cationic starch present, thus explaining their interaction. This study indicates that CNF from OCC can be combined with cationic starch at appropriate levels to improve properties of the resulting board without critically decreasing the drainage rate.

The fire performance of fire retardant-treated wood can be evaluated based on how much of the chemical retardant is used. Therefore, methods for identifying chemical content in wood are needed. Stereo images of wood samples before and after the fire retardant treatment were captured using micro-focus X-ray computed tomography. Image brightness values, indicating concentration, were calculated using binarized images sliced from the X-ray images. Changes in integrated brightness values before and after treatment showed a strong positive correlation with chemical content at a 1% significance level. The chemical content of the retardant-treated wood was predicted based on the relationship between the two. The predicted values were in agreement with the values measured using the leaching method. Fire performance tests of the fire retardant-treated wood were conducted using a cone calorimeter. The treated wood was classified as fire-retardant and non-combustible wood. In addition, the fire performance predicted by the relationship between changes in integrated brightness values and chemical content agreed with the classification by the fire performance test. These findings suggest that X-ray computed tomography can be potentially used to predict the chemical content of fire retardant-treated wood.

Wooden packaging boxes and pallets are used in a wide range of applications. In this work, LVL from the same source and batch were used as the base material. After dynamic detection and grading, they were divided into two grades (A and B), according to their differences in elastic modulus. The packaging boxes and pallets of the same specifications were designed and manufactured as the research objects. Four mechanical properties studies and related analyses were performed. The three mechanical tests showed different deflection values of the two packaging boxes A and B, and the maximum error was 6.93%. In the rotational edge drop test, the edges of the nether end rails of the two grades of LVL boxes were damaged to varying degrees. Additionally, the nails at the connection between the middle longitudinal beam and the bottom plate also appeared to be pulled out, and the parts made of B-grade LVL were more obvious. The results show that the dynamic detection and quality grading for LVL can effectively distinguish the material grade. The grading results were consistent with the mechanical properties of the LVL packaging boxes and pallets of corresponding grades, which are suitable for use in production lines.

Hot surfaces are an integral part of the technological processes of agricultural crop processing. Their surface temperature at critical points can exceed the minimum ignition temperature. This paper aims to experimentally observe the behaviour of hay when exposed to radiant heat. The model presented here is implemented using a hot plate device. The hot plate has a defined temperature-time curve. Based on the above, the hot plate temperature is determined as the minimum ignition temperature of the investigated hay specimen. At the same time, the temperature inside the tested material was monitored. The heterogeneity of the above specimens significantly influenced the nature of the biomass thermal degradation. The ignition temperature of the hay (406 °C) can serve as a tool for fire risk assessment.

The diameter of nanocellulose most often is detected using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and other related techniques. These detection methods are not only expensive, time-consuming, and complicated to operate, but also are not conducive to the detection of the diameter during the actual production of nanocellulose. In this study, the settling height of cellulose nanocrystals (CNCs) was related to CNC diameter by sedimentation method to find a convenient technique for the rapid detection of CNC diameter. The results showed that when the CNC concentration was at 0.2 wt%, the sodium chloride (NaCl) dosage at 40 g/L, and at the standing time of 48 h, the CNC sedimentation performance was the best. Furthermore, with the increase of CNC diameter, the settling height of CNCs gradually decreased. The relationship between CNC diameter and settling height was Y (Settling height) = -30.17 ln(X (CNC diameter)) + 123.64; and the coefficient of determination for the fit was 0.9965. This research provides a new method for the diameter detection of CNCs in the actual CNCs production in enterprises.

Cellulose is a primary structural component of plants and is one of the most abundant polymers on the Earth. Degradation of this recalcitrant component of plant biomass is an important process in the global carbon cycle and can potentially provide feedstock for biofuels. Fungi and bacteria are the primary organisms able to breakdown biomass-derived cellulose. Anaerobic bacteria, present in cellulose degrading ecosystems, such as compost piles, soils rich in organic matter, aquatic sediments, and digestive systems of herbivores, have developed efficient pathways to maximize metabolic energy from biomass degradation. In the absence of terminal electron acceptors, such as oxygen, hydrogen-producing pathways are common methods of electron carrier recycling. Electron bifurcating systems linked to hydrogen metabolism play an important role in anaerobic metabolism. In this study, samples from environmental cellulose-degrading microbial communities were collected, and the metabolic products produced during anaerobic cellulose degradation were examined. Samples from different environments produced different fermentation products from cellulose, suggesting flexibility in the fermentative degradation pathways. The most abundant products observed included hydrogen, acetate, propionate, butyrate, ethanol, and methane.