Volume 14 Issue 4

To improve the appearance of the black locust wood under heat treatment, ammonia (AM), acetic acid (AA), and ammonium acetate (AMA) were adsorbed into the black locust wood flour, with or without aluminum sulfate octadecahydrate (ASO). The color parameters (CIE L*a*b*) of the black locust wood flour treated with different conditions were measured. Diffuse reflectance ultraviolet-visible spectroscopy (DRUV-Vis) and the attenuated total reflection/Fourier transform infrared spectroscopy (ATR-FTIR) were conducted to reveal the changes of the chromophore systems. X-ray photoelectron spectroscopy (XPS) was used to demonstrate the extreme valence of the atomic content and the occurrence of a coordination reaction. The color of the wood flour became reddish after the treatment with AMA+ASO. There was an increase in carbonyl structure and carboxyl structure of the wood flour treated with AMA and ASO.

Wood texture has a beautiful appearance and tactile feeling, making it very appropriate for furniture applications. However, the fabrication of a wood texture on wood-based boards can be inefficient and less green when performed using conventional methods. In this study, a wood-like surface on a wood-based board was designed to imitate a wood texture using 3D printing technology. To obtain a high-quality wood texture template for 3D printing, the sharpness of the wood texture was evaluated by image sharpness models, and the scanned wood texture was optimized by colorimetric parameter and sharpness adjustments. The wood texture coating, which was mainly composed of acrylated oligomers, was UV-inkjet 3D printed on the medium-density fiberboard (MDF) from an obtained template. The properties of the printed wood texture coating on the MDF, including its gloss, wearability, adhesion, and hardness, were measured. The results showed that a wood texture coating with high processability can be feasibly 3D printed on MDF to obtain comparable decoration using commercial products.

The structures, crystallinities, Miller indices, and particle sizes of cassava treated with microwave radiation or saline water were analysed and compared. Cassava was milled to sizes of 100 to 120 mesh and then dried under solar radiation for several days. The first set of substrates was treated by microwave radiation at 300 W for 10, 20, or 30 min or at 1000 W for 8 min. The second set of substrates was immersed in saline water for 5 days at salt concentrations of 3.43% or 10% (w/w). The treated substrates were characterised by x-ray diffraction, Fourier transform infra-red spectroscopy, and scanning electron microscopy, and the results were compared with the characteristics of the native substrate. There were significant differences in the characteristics of the microwave- and saline water-treated cassava. Crystallinities of the microwave-treated substrates were lower than those of the saline water-treated samples. A large shift (change in 2θ) in the diffraction peaks was observed for the treated substrates as compared with the native substrate. Examination of the surface morphology suggested that saline water enabled the dissolution and elimination of the undesirable fibres in the substrate; this was not observed for the microwave-treated substrate.

The chemical compositions were investigated for pine essential oils obtained through a solvent-free microwave assistance extraction system (ME) and a conventional hydrodistillation system (HD). The essential oils of P. pinea, P. nigra, P. brutia, and P. sylvestris sawdust were analyzed by gas chromatography and mass spectroscopy (GC-MS). The main components of the pine essential oils were D-limonene (52.8% for ME and 76.6% for HD), β-caryophyllene (12.4% for ME), β-myrcene (2.89% for ME and 1.48% for HD), sesquiterpene hydrocarbons (25% for ME and 9.79% for HD), and total sesquiterpene (25.25% for ME and 9.79% for HD) for P. pinea; D-limonene (28.1% for ME and 79.2% for HD) for P. nigra; α-pinene (76.6% for ME and 77.3% for HD), diterpene hydrocarbons (94.17% for ME and 95.62% for HD), and total diterpenes (94.94% for ME and 96.3% for HD) for P. brutia; β-pinene (36.7% for ME and 42.4% for HD), terpineol, (13.8% for ME and 6.06% for HD) diterpene alcohol (26% for ME and 12.57% for HD), and total oxygenated terpenes (26% for ME and 12.57% for HD)for P. sylvestris. Moreover, the ME was able to produce more diterpene alcohols and sesquiterpene hydrocarbons while the HD showed higher potential for the diterpene hydrocarbons. According to the heat-map correlation, P. pinea showed high similarity with P. nigra, while P. sylvestris was related to P. brutia.

The properties of laminated wood prepared from sengon wood (Falcataria moluccana Miq. Barneby & Grimes) bonded with a modified gutta-percha (MGP) adhesive at various laminae surface roughness profiles were investigated. The wood laminae were sanded using sand papers of KAG grit designation of 80, 100, 150, 220, 300, and 400. A lower value of KAG grit designation with a lager particle size of sand resulted in a rougher surface of the bonded laminae; a rougher laminae surface profile resulted in a greater shear strength of the laminated wood. The shear strength was highest for laminated wood treated with sand paper of KAG 80 and smallest for laminated wood treated with KAG 400. In general, the bonding strength was enhanced with decreasing KAG grit designation. The adhesion performance, in terms of spread and adhesive penetration, improved after sanding, which widened the contact area on the wood surface.

Plantation poplar (Populus x euramericana cv. Pannonia) wood samples were steamed at 100 °C, 110 °C, and 120 °C and then irradiated by a strong UV emitter mercury lamp to test their colour stability. The colour change was evaluated and presented in a CIE Lab colour coordinate system. For the control, unsteamed poplar specimens were irradiated using the same mercury lamp. A considerable increase in colour saturation in the specimens was generated by steaming, and the saturation value further increased during the UV treatment. The lightness value of the unsteamed control specimens decreased continuously during the entire UV irradiation period. In contrast, the lightness value of the steamed samples decreased only during the first seven hours of the UV treatment and remained constant afterward. Steaming enhanced the redness stability of the poplar wood against UV irradiation. Modification of wood components during steaming at 120 °C stabilised the poplar wood redness against short-term photodegradation. Steaming slightly reduced the yellow colour sensitivity of the poplar to photodegradation.

Cassava bagasse (CB) was liquefied using polyethylene glycol to prepare polyol. The liquefied cassava bagasse (LCB) was reacted with polymeric diphenylmethane diisocyanate (PMDI) to produce novel bio-based polyurethane foams (PUF) via a one-pot process. The results showed that the density of the LCB-PUF was in the range of 0.027 to 0.039 g/cm3. When the LCB was used to instead of polyether polyol with a replacement ratio rising from 20% to 100%, the compressive strength of the LCB-PUF decreased from 0.171 to 0.057 MPa. The TGA results indicated that a higher replacement ratio (≥60%) of the LCB had a negative effect on the thermal stability of LCB-PUF, and the PUF with heterogeneous walls and irregular pore shapes was mainly caused by the high replacement ratio of the LCB. In addition, the mechanical properties of the LCB-PUF were improved through the adjustment of the [NCO]/[OH] ratio and the foam additive content.

The effects of nanoclay content were investigated vs. the mechanical, thermal, and morphological characteristics of a nanocomposite made from poplar wood flour and polypropylene. The wood flour, polypropylene, nanoclay, and the maleic anhydride grafted polypropylene (MAPP) were mixed in an extruder, and the test specimens were made via injection casting. Then, the mechanical and thermal properties were examined. The results showed that the tensile strength, flexural strength, and flexural modulus were improved when the wood flour content increased from 40% to 50%. Additionally, increasing the wood flour content from 40% to 60% enhanced the tensile modulus. The addition of nanoclay at dosages up to 2 wt% enhanced the tensile strength and the tensile modulus, whereas these properties were degraded with the addition of nanoclay at up to 4 wt%. The tensile strength and flexural modulus improved when the nanoclay content increased up to 4 wt%. The crystallinity enthalpy decreased when the wood flour content increased.

In order to find the suitable alkali recovery process for linter and reed pulping discharges, the physicochemical properties of the black liquor solids from linters pulping and black liquor solids from reed pulping were analyzed. The swelling volume index, calorific value, and pyrolysis characteristics of five samples of mixed black liquor solids were tested. The kinetics of the combustion process of the samples were further studied. The results showed that the calorific value and swelling index of the reed black liquor was higher and its inorganic content was lower. During the combustion period, the droplet undergoes four stages; drying, devolatilisation or pyrolysis, char burning, and smelt reaction. With the increase of reed pulping black liquor solids in the sample, the activation energy decreased, while the frequency factors increased. As a result, the combustion performance of the mixed solids was significantly improved.

The effects of bulk density on the structure and combustion characteristics of rice husk (RH) char were studied under isothermal conditions. The char from each reaction stage was obtained through pyrolysis of RH/Al2O3. Thermogravimetric-Fourier transform infrared analysis was used to study the release of gaseous products during the fine particle pyrolysis of RH/Al2O3. The results showed that the bulk density of the particles seriously affected the release rate and product distribution of gaseous products during pyrolysis, especially in the release phase of volatiles. In comparison, biomass pellets had a faster pyrolysis reaction rate at low bulk densities, which resulted in lower contents of O and H in the char obtained at this stage, and the aromatic structure content slowly increased. In the carbonization stage, the low bulk density promoted the increase in surface area and pore volume expansion of char. The degree of aromatization in char was higher, but the carbon content decreased. The addition of Al2O3 limited the growth of aromatic crystallites, while the char obtained at high bulk density tended to be graphitized. The char reactivity at the two bulk densities first decreased and then slightly increased, but the char obtained at high bulk density had better combustion reactivity.