Research Articles

In this study fiber cell wall porosity was altered by fiber line simulation in a laboratory. The changes in the fiber cell porosity were analyzed with a water retention value (WRV) test. Pore size distributions were measured by differential scanning calorimetry (DCS), and atomic force microscopy (AFM) was used to determine the cell wall pore area from cross sections of the S2 layer of the cell wall. WRV was shown to correlate with the amount of water in the pores with a diameter of at least 200 nm. Changes in the non-freezing and total bound water did not affect the WRV. The calculated shrinkage forces generated by the capillary forces in different pore cell wall structures correlated with the sheet densities generated by fiber networks. It was observed that the swelling of the cell wall, defined as an increase in the diameter of the cell wall, was most likely not occurring or was very difficult to detect.

Moringa oleifera seeds were investigated for the removal of manganese ions from aqueous solutions. The seeds utilized were obtained from plants grown in Uberlândia, Brazil. After being dried and pulverized, the seeds were treated with 0.1 mol L-1 NaOH. Using the optimized methodology (50 mL of 4.0 mg L-1 Mn(II), pH range of 4.0–6.0, contact time of 5 min, and biosorbent mass of 0.5 g) it was found that 100% of Mn(II) could be removed from water samples. In order to remove up to 95% of Mn ions in 50 mL of a laboratory residue produced during biochemical oxygen demand determinations with 112.0 mg L-1 of manganese, the contact time and pH were maintained, but a mass of 3.0 g was used. The kinetic data were fitted to a pseudo-second-order kinetic model. The sorption data were fitted satisfactorily to the Langmuir and Freundlich isotherm models. Evaluation applying the Langmuir equation gave the monolayer sorption capacity as 5.61 mg/g. In this application the method was found to be efficient, fast, simple, and economical.

A group of biomass-derived lignins isolated using organosolv fractionation was characterized by FT-IR spectral and thermal property analysis coupled with multivariate analysis. The principal component analysis indicated that there were significant variations between the hardwood, softwood, and grass lignins due to the differences in syringyl and guaiacyl units as well as the different processing temperatures and times used to isolate the lignins. Partial least squares regression revealed that the concentration of syringyl units was the foremost factor behind the variation in glass transition temperature (Tg) for each lignin sample. It was concluded that structural variations resulting from altering the processing time and temperature and the lignin species directly affect the thermal properties of the lignin. Therefore, by determining the thermal properties of a lignin sample, a basic understanding of its structure can be developed.

A novel calcium silicate filler can be made from fly ash. This new filler, known as fly ash based calcium silicate (FACS), has a highly porous surface structure, high brightness (91% ISO), low bulk density (0.31 g/cm3), and high specific surface area (121 m2/g). In this paper, its potential application as a paper filler was studied and its effect on drainage, retention, and paper properties was investigated. The results from dynamic drainage tests showed that FACS had similar drainage and retention behaviors to the conventional precipitated calcium carbonate (PCC). Physical tests indicated that FACS-filled paper had higher tensile, burst, and tear indices, but lower brightness and opacity than those loaded with PCC. A more important finding was that the bulk of paper can be increased by 56.4% with 20% FACS content in paper relative to the control (no filler addition).

Hemp fibers–reinforced unsaturated polyester (UP) composites were prepared by hand lay-out compression molding. Hemp fibers were treated with isocyanatoethyl methacrylate (IEM), using dibutyltin dilaurate as a catalyst. The results indicated that fiber treatment significantly increased tensile strength, flexural strength, flexural modulus, and water resistance of the resulting composites, and yet decreased the impact strength of the composites. The water absorption characteristics for composite samples immersed in water at room temperature followed Fickian behaviour, but for those evaluated at temperature 100 °C, there was a deviation from Fickian behaviour. Scanning electron microscope graphs of the tensile-fractured surface of hemp–UP composites revealed that fiber treatment with IEM greatly improved the interfacial adhesion between hemp fibers and UP resins. Fourier transform infrared analysis of the treated fibers showed that some IEM was covalently bonded onto hemp fibers.

In this study, lignocellulosic biomass from oil palm trunk (OPT) and oil palm frond (OPF) of oil palm tree, Elaeis guineensis, were treated using the microwave-alkali (Mw-A) method, and their chemical constituents, namely cellulose, hemicellulose, and lignin, were analyzed. A number of instruments, i.e. FESEM, FT-IR, and XRD, were employed to analyze the morphology and structural changes of biomass. After the Mw-A pretreatment, it was revealed that the amount of cellulose released was up to 41.55% for OPT and 64.42% for OPF. There was also a huge degree of reduction in hemicellulose, up to 64%, but lignin removal saw a fair reduction with only 15.33% for OPT and 17.97% for OPF. The results revealed that the Mw-A pretreatment is capable of disrupting the OPT and OPF.

The chemical and morphological changes in heartwood specimens of Liquidambar orientalis Mill. caused by the white-rot fungus Trametes versicolor and the brown-rot fungi Tyromyces palustris and Gloeophyllum trabeum were studied by wet chemistry, FT-IR, GC-MS analyses, and photo-microscopy. According to GC-MS results, 26 extracts identified in the ethanol/toluene extraction and 17 in the ethanol extraction were found. Heartwood specimens of L. orientalis were highly susceptible to the fungi tested. While 1% NaOH solubility increased 35% in the specimen decayed by T. palustris, only an 8% increase was seen in the specimen exposed to T. versicolor when compared to the control specimen. Decayed wood by T. palustris showed a 5.5% increase in the Klason lignin content when compared to control specimens; however, the Klason lignin content decreased after a T. versicolor attack for 12 weeks. A T. versicolor attack in the cell walls was seen both from the lumina and from the cell corners, and the attack from the cell corners was mainly clear in ray parenchyma cells. An excessive destruction was detected in the wood structure attacked by T. palustris. The cell collapse was caused by a distortion in the plane of the wood cells. This extensive degradation was seen in all types of cell walls. Cracks in the cell walls were also detected in the specimens.

The objective of this paper was to investigate the contact angles of single bamboo fibers at different temperatures and relative humidities in comparison to terylene fibers. Comparative tests were done for three other natural fibers (ramie, jute, and kendir) under the same conditions. Contact angles were also measured for bamboo strips. The results showed that with increasing temperature and constant relative humidity, the contact angles of bamboo fibers decreased, whereas those of terylene fibers increased. The contact angle of the bamboo fiber increased significantly, while that of the terylene fibers rose a little with increasing relative humidity at constant temperature. The contact angles of the single bamboo fibers were higher than those of ramie fibers, but lower than jute and kendir fibers after the same chemical treatment because of different diameters, surfaces, and chemical components. In comparison with bamboo strips, the contact angles of single bamboo fibers were much higher and changed with a different trend. Meanwhile the contact angles of cross-section, radical section, and tangential section of bamboo also changed differently.

Laminated veneer lumber (LVL) panels made from poplar (Populus ussuriensis Kom.) and pine (Pinus sylvestris L. var. mongolica Litven.) veneers were tested for mechanical properties in this work. Four different nondestructive testing (NDT) methods and the static bending test were conducted on the LVL. The NDT methods included the longitudinal vibration method, longitudinal transmission method, and in-plane and out-plane flexural vibration methods. The effects of relative humidity on the modulus of elasticity (MOE) and bending strength (MOR) of LVL with vertical load were investigated. Four relative humidities were tested, namely 40%, 50%, 60%, and 70%. The feasibility of NDT testing on LVL was analyzed by fuzzy and classical mathematics. The results showed that the MOE and MOR of LVL diminished with an increase of relative humidity, and the analysis results of fuzzy neartude and correlation coefficients were same. There was a good linear correlation between NDT results and MOE or MOR of poplar and pine LVL.

Many biotechnological processes pursuing sustainability aim for effective, inexpensive, and environmentally friendly alternatives to replace conventional practices. Laccase-containing lignocellulolytic systems from white rot fungi have been shown to be an efficient enzymatic tool for ecofriendly biological treatments. One objective of the biotechnological enzymes production process is to find optimum growing and secretion conditions for a selected fungus. In this work, different fungi isolated from the Misiones rainforest (Coriolus versicolor f. antarcticus BAFC-266, Ganoderma applanatum strain F, Phlebia brevispora BAFC-633, and Pycnoporus sanguineus BAFC-2126) were incubated at different temperatures (25, 29, 33 °C) and pH values (3.5, 4.5, 5.5) under static conditions for 7, 10, and 14 days to evaluate their growing ability and laccase (Lac) production. Results revealed specific favorable conditions for growth and protein secretion depending on the fungus under consideration, making it necessary to adjust these parameters for each particular case. The combined effect of these cultivation parameters showed a marked influence on the secreted Lac activity by P. brevispora BAFC 633, with the highest activity (~ 240 U/l) at 29 ºC and pH 4.5 at the 10th day of cultivation. The presence of Lac isoenzymes also depended on the pH, temperature, and time of cultivation for the different tested fungi.