Research Articles

A new deformation technique of wood flow forming is promising for industrial uses of solid wood. Flow deformability, size stability, and good mechanical properties were obtained by using wood impregnated with low molecular weight phenol formaldehyde (PF) resin. In this study, to clarify the effect of the PF resin and moisture contents in wood on the flow deformability (extrudability) and the mechanical properties of the product (extrudate), a lateral extrusion was conducted by using wood impregnated with various contents of PF resin and three levels of moisture content. The results indicated that the extrudability of wood impregnated with PF resin improved with an increase in both PF resin and moisture content. The mechanical properties of the extrudate worsened with increases in the moisture content of the wood impregnated with PF resin. Because most of the water in the wood remained in the mold during the extrusion process, chemical changes of the wood substance and PF resin occurred due to steam forming under the high temperature and pressure of the extrusion. The steam worsened the mechanical properties of the extrudate.

This effects of ozone and nanocellulose treatments were studied relative to the optical and strength features of chemical mechanical pulp (CMP) papers. An ozone treatment was performed at room temperature, and then nanocellulose was added. Sixty-gram handmade papers were made, and their physical, mechanical, and morphological properties were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). With the ozone treatment, changes in the optical features were not significant at the 95% level; however, the addition of nanocellulose led to significant changes: the tensile strength, burst strength, air resistance, opacity, and brightness increased by 14.1%, 15.9%, 34.8%, 2.8%, and 3.2%, respectively, in comparison with the control sample. The enhancement with nanocellulose reduced the tear strength, coarseness, and yellowness by 15.7%, 12.9%, and 7.6%, respectively, compared with the control sample. The crystallinity of neat nanocellulose was 65.59%, while the crystallinities with the use of 5% to 10% nanocellulose were 72.41% and 62.26%, respectively. The SEM results indicated that using a 10% nanocellulose treatment led to the reduction of the CMP paper’s porous character.

The aim of this research was to fabricate epoxy nanocomposites by utilizing the developed nano filler from oil palm mills agricultural wastes oil palm empty fruit bunch (OPEFB) fibers for advanced applications. Epoxy-based polymer nanocomposites were prepared by dispersing 1, 3, and 5 wt. % nano OPEFB filler by using a high speed mechanical stirrer through hand lay-up technique. The mechanical (tensile and impact) properties and morphological properties of nano OPEFB/epoxy nanocomposites were examined and compared. Morphological properties were analyzed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to look at the dispersion of the nano OPEFB filler in the epoxy matrix. The tensile and impact properties of nanocomposites increased until 3% nano filler loading, but beyond 3% they decreased. Overall mechanical properties reached maximum values for 3% loading, due to better stress transfer owing to homogenous dispersion of nano OPEFB filler within epoxy matrix. The observed results were also confirmed by SEM and TEM micrographs.

This study aimed to investigate the major content of merbau extractives (ME) and their potential use as an impregnating material for low-quality timber. Extraction was done by maceration with ethanol, ethyl-acetate, and hot-water. Physico-chemical, phyto-chemical, UV-visible, and infrared spectroscopy, as well as py-GCMS analysis were then performed on dried extract. The results showed that organic solvent extractions resulted in much higher yields, by 12.50% than that of hot water (1.10%). The merbau extractives liquid obtained had a low acidity, with a pH ranging from 5 to 6, which is typical of phenolic compounds. Flavonoids and phenolics were found as the major compounds.  UV-vis spectra showed that ME (λ=279 nm) consists of conjugated or aromatic systems, similar to standard resorcinol, which was used as the reference (λ=274 nm). The FTIR spectra showed the absorption bands at 3369 cm-1 that represent the functional group of hydroxyl (OH) bonds, and 1619 and 1510 cm-1, representing the aromatic ring (C=C), which could be associated with resorcinol. The Py-GCMS showed that ME is predominated by resorcinol (C6H6O2) with a 79% concentration. The ME could be potentially used for producing phenolic/resorcinolic resin through polymerization, which could be applied for wood impregnation.

Tannin-furanic biobased foams, based on the co-reaction of bark-derived condensed tannins and thermoset furanic polymers, have low thermal conductivity, are self-extinguishing, and have high fire resistance, which allows their development for several industrial uses. One of their main drawbacks, however, is the absorption of water within the foam itself. Another problem is the rather friable surface, which is a definite drawback for some potential applications. In this work, these two problems are minimized or eliminated by introducing a component of oil-grafted tannin in the foam formulation. The incorporation of fatty chains markedly decreased foam friability and increased water repellency in the body of the foams. These properties and the compounds formed by fatty acids grafting onto the tannin flavonoids were extensively tested.

The mechanical properties of natural fiber composites can be strengthened in the longitudinal direction if the fiber is formed in a parallel manner. Reconstituted cotton stalk lumber and mulberry branch lumber were fabricated using hot-press technology, and the effects of fiber morphology on their mechanical and bonding properties were investigated. The fiber bundle size had a great influence on the mechanical and bonding properties of the final products. The maximum specific modulus of rupture (MOR) and specific modulus of elasticity (MOE) of the reconstituted lumber were obtained for medium-size fiber bundles, and the maximum MOR and MOE of reconstituted cotton stalk lumber was 130.3 MPa·g-1·cm-3 and 12.9 GPa·g-1·cm-3, respectively. The maximum MOR and MOE of the mulberry branch lumber was 147.2 MPa·g-1·cm-3 and 14.7 GPa·g-1·cm-3, respectively. Mechanical interlocking structures in the lumber were observed via fluorescence microscopy, showing that phenol-formaldehyde adhesive had penetrated into several cell layers of the fiber bundle under heating and pressure. The adhesive penetration capacity was stronger when the fiber bundles were smaller in size and density. The reconstituted lumber fabricated from both materials exhibited excellent mechanical performance in the parallel direction. Therefore, reconstituted cotton stalk and mulberry branch lumber are attractive potential materials for the construction industry.

The aim of this study was to identify cellulolytic fungal strains capable of degrading cellulose from an aerated lagoon in a pulp and paper mill. Four fungal strains that were found to be highly active were isolated on carboxymethyl cellulose (CMC) and suggested to be CMCase/endoglucanase. The identified strains were Aspergillus niger,Penicillium sp., Aspergillus fumigatus,and Mucor sp. All the strains were studied in terms of cultural morphological characteristics and microscopic examinations. The endoglucanase with the highest isolate production was Penicilliumsp., which also showed the highest qualitative endoglucanase activity (1.3 cm), in addition to the main activity of endoglucanase with 297 mmol/mg.min after 116 h. The results indicated that CMC is able to induce endoglucanase enzyme production and that the fungal isolates showed significant cellulose degradation properties.

Green fir wood (Pseudotsuga menziesii) was modified with polyethylene glycol (PEG) to produce wood composites for energy storage and conversion. The PEG-modified wood composites were evaluated based on their dimensional stability, durability, and thermal properties by various analytical methods. The differential scanning calorimetry (DSC) results showed the melting temperature and the latent heat of the phase change material (PCM) composite were 26.74 °C and 73.59 J/g, respectively. Thermal cycling tests and thermogravimetric analysis confirmed the composite exhibited good thermal stability, reliability, and chemical stability. All treated specimens were free from noticeable defects, and the addition of a surface varnish coating prevented PEG from leaching. The PEG-modified composites exhibited improved dimensional and thermal performance, which makes this material a potential candidate for economical and green, lightweight building materials.

In this study, 4-mm-thick medium-density fiberboard (MDF) panels were heat-treated at 140 °C for 30 or 60 min and at 180 °C for 30 or 60 min. Then, 10-mm-thick lightweight honeycomb paperboards made from kraft paper (130 g/m2, cell diameter of honeycomb, 14 mm; compression strength, 0.21 N/mm2) were faced with the untreated and heat-treated MDF panels (thickness: 4 mm) using a two-component polyurethane adhesive. The density, thickness swelling, water absorption, and flexural properties of the paperboards faced with the untreated and heat-treated MDF panels were investigated. The lowest flexural strength (3.76 N/mm2) and flexural modulus (392 N/mm2) values were found in the specimens faced with the MDFs treated at 180 °C for 60 min, while the highest flexural strength (4.20 N/mm2) and flexural modulus (457 N/mm2) values were found in the specimens faced with the untreated MDFs. The loss in strength was primarily attributable to the degradation of hemicelluloses, which are less stable to heat than cellulose and lignin. The thickness swelling and water absorption of the honeycomb paperboards faced with the heat-treated MDF panels significantly (p < 0.01) decreased with the increase in heat-treatment temperature and duration.

Dimensional stability is a key property of wood that significantly affects its applications. The effect of an ultrasound pretreatment on poplar wood (Populous tomentosa) dimensional stability was examined. During the pretreatments, wood samples were immersed in distilled water and treated ultrasonically under three different powers and frequencies. The samples were then analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The chemical transformation of the cell-wall material was studied and then associated with the change of water absorption and the swelling coefficient. The results showed that the water absorption decreased after the ultrasonic pretreatment. The axial and radial swelling coefficients of the pretreated samples decreased, while the tangential swelling coefficients increased. The volumetric swelling coefficient of pretreated specimens fluctuated near 4.48% (the volumetric swelling coefficient of untreated wood). Ultrasonic pretreatment increased the number of hydrophilic groups, such as the hydroxyl, acetyl, and uronic ester groups. Meanwhile, the pretreatment also increased the degree of crystallinity and reduced the available polar groups. These two factors together caused the change of the moisture absorption and the swelling coefficient of the pretreated wood. These conclusions suggest that the ultrasonic pretreatment is a promising method for further chemical modification of wood.