Research Articles

To increase understanding of breakdown strategies for Mozambican timber, simulations were carried out using different sawing patterns that can be alternatives to the low degree of refinement performed for export today. For the simulations, 3D models of 10 Jambirre and 5 Umbila logs were used. The log shape was described as a point cloud and was acquired by 3D-laser scanning of real logs. Three sawing patterns (cant-sawing, through-and-through sawing, and square-sawing) were studied in combination with the log positioning variables skew and rotation. The results showed that both positioning and choice of sawing pattern had a great influence on the volume yield. The results also showed that the log grade had an impact on the sawing pattern that should be used for a high volume yield. The volume yield could be increased by 3 percentage points by choosing alternative sawing patterns for fairly straight logs and by 6 percentage points for crooked logs, compared to the worst choice of sawing pattern.

Modified starch was prepared in this work by acid-thinning and oxidizing corn starch with ammonium persulfate. Also, starch-based aqueous polymer isocyanate (API) wood adhesive was prepared. The effect of the added amount of modified starch, styrene butadiene rubber (SBR), polymeric diphenylmethane diisocyanate (P-MDI), and the mass concentration of polyvinyl alcohol (PVOH) on the bonding strength of starch-based API adhesives were determined by orthogonal testing. The starch-based API adhesive performance was found to be the best when the addition of modified starch (mass concentration 35%) was 45 g, the amount of SBR was 3%, the PVOH mass concentration was 10%, and the amount of P-MDI was 18%. The compression shearing of glulam produced by starch-based API adhesive reached bonding performance indicators of I type adhesive. A scanning electron microscope (SEM) was used to analyze the changes in micro-morphology of the starch surface during each stage. Fourier transform infrared spectroscopy (FT-IR) was used to study the changes in absorption peaks and functional groups from starch to starch-based API adhesives. The results showed that during starch-based API adhesive synthesis, corn starch surface was differently changed and it gradually reacted with other materials.

Co-pyrolysis of Shenmu coal (SM) and cotton stalk (CS) at different blend ratios were carried out in a tubular furnace. The pyrolysis temperature was up to 600 °C at 5 °C/min and kept for 15 min. The results indicated that there was an interactive effect between SM and CS, which increased the tar yield. Moreover, the content of light components in co-pyrolysis tar from all CS/SM blend ratios was higher than that in the tar derived from SM pyrolysis. This interaction not only increased tar yields but also upgraded the quality of tar in the co-pyrolysis process. Compared with the co-pyrolysis of de-ashed CS and SM, the inherent minerals of CS had great effects on the co-pyrolysis tar yield. The analysis results of n-hexane soluble extracted from co-pyrolysis tar by gas chromatography/mass spectrometry indicated that the organic matters of CS had a significant effect on the alkene formation of tar during co-pyrolysis. The maximal tar yield was 13.73 wt% (daf) and the yield of n-hexane soluble reached 11.13 wt% (daf) under optimum conditions.

To apply bacterial cellulases for efficient saccharification of biomass, three Clostridium thermocellum cellulases and a Thermoanaerobacter brockii β-1,4-glucosidase were synthesized in Escherichia coli, and the proportions among them were optimized. When the activities of CelD, CBHA, CBH48Y, and CglT were set at 554, 0.91, 0.91, and 856 mU per assay, respectively, the percent conversion of regenerated cellulose (0.92 g/L) reached 80.9% within 24 h at 60 °C without shaking. Meanwhile, the percent conversion of pretreated corn stover (0.62 g/L) reached 70.1%. Gradually raising the loads of regenerated cellulose from 0.92 to 4.58 g/L resulted in a linear increase in glucose production from 870 to 3208 μg (R2=0.997), as well as a decrease in the percent conversion from 80.9% to 59.6%. These findings suggested that the cellulase cocktail is efficient in saccharification of regenerated cellulose, as well as pretreated corn stover, and has potential applications in the biofuels industry.

To improve the performance of polyvinyl chloride (PVC), composites incorporating polyvinyl chloride (PVC), attapulgite nanoparticles (ANPs), and microcrystalline cellulose (MCC) were successfully prepared. The composites had higher vicat softening temperatures (VSTs) and the MCC had a great influence on mechanical properties of the composites. When MCC was added from 0 to 5 per hundred parts of PVC (phr), the mechanical properties of the composites increased, but the mechanical properties of the composites decreased when the MCC was more than 5 phr. The tensile breaking stress, tensile strength, and impact strength were maximized with increases of 19.76 N (4.1%), 29.66 MPa (15.5%), and 13.8 MPa (7%) when 5 phr MCC was added. Infrared spectral analysis indicated that MCC and ANPs were present in the composites. Scanning electron microscopy showed that the composites system was distributed into two phases, which indicated that MCC in composites was dissolved in the PVC matrix, and some of MCC coated the surface of ANPs as a compatibilizer. Overall, this study provided a promising method for PVC modification to improve its performance.

The desilication effects of aluminium sulphate and sodium aluminate on kraft bamboo pulp during the cooking process were investigated in this study. Furthermore, the residual aluminium ion concentration in the resulting black liquor was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) to evaluate the scaling properties of black liquor during the evaporation process. Atomic force microscopy (AFM) and scanning electron microscopy with energy-dispersive X-ray spectroscopy(SEM-EDS) analysis showed that aluminium salts could react with silica to form a silica-alumina compound, which can adhere to the fibre surface during the cooking process. As a result, the silicon content in the black liquor could be effectively decreased by the addition of aluminium sulphate and sodium aluminate. A silica removal ratio of 74% could be achieved when the loadings of aluminium sulphate and sodium aluminate were 2.0 wt.% and 1.5 wt.%, respectively. Finally, the concentration of aluminium ions was 7.31 ppm under optimised conditions. Based on these considerations, any amounts of aluminum ion passing into the black liquor are unlikely to contribute to scaling problems.

Methylated fatty acid (FA) compounds in the heartwood and bark of some softwood species, specifically Pinus sylvestris, Abies alba, Picea abies, and Larix decidua, grown in the Czech Republic were evaluated. Strong H2SO4 was used for methylation of the lipids. The highest content of lipid was found in P. abies bark (40.132 mg/g o.d. sample), and the lowest content was in A. alba wood (11.027 mg/g o.d. sample). The highest concentration of FAs was observed in L. decidua bark. The highest percentages of FAs in wood of P. sylvestris were arachidic acid and oleic acid. In bark, the highest percentages of FAs were stearic acid, palmitic acid, and oleic acid. The FAs with the highest concentrations in A. alba wood were arachidic acid, palmitic acid, pentadecanoic acid, and margarinic, and those in bark were behenic acid, lignoceric acid, and arachidic acid. P. abies wood FAs showed arachidic acid, palmitic acid, and margarinic acid, and the bark contained lignoceric acid and arachidic acid. The FAs of L. decidua wood were arachidic acid, palmitic acid, and stearic acid, and in bark they were pentacosylic acid, docosahexaenoic acid (DHA), lignoceric acid, arachidic acid, and behenic acid. The lack of typically dominant unsaturated fatty acids (e.g. 18:1, 18:2), compared to literature values were attributed to the application of strong acid for the hydrolysis.

Wood and bark oil extractives components (OECs) of Pinus sylvestris, Abies alba, Picea abies, and Larix decidua grown in the Czech Republic were analyzed using gas chromatography/ mass spectrometry (GC/MS). The analysis showed the presence of monoterpene, sesquiterpene, diterpenoids, and resin acids. The highest percentages of OECs in the wood of P. sylvestris were α-fenchyl alcohol (26.04%), D-fenchyl alcohol (12.39%), and L-borneol (8.81%); the OECs in the bark included α-methyl-γ-butyrolactone (31.88%) and isodecyl octyl phthalate (15.85%). The most frequently occurring OEC in A. alba wood were 4-hydroxy-4-methyl-2-pentanone (73.36%), α-cedrol (10.08%), and 2,6-dimethyl-1,3,6-heptatriene (7.35%); the most OECs in the bark were di(2-ethylhexyl)phthalate (59.83%), methyl cyclopentane (16.63%), and 13-epimanool (6.31%). P. abies wood OECs included 4-hydroxy-4-methyl-2-pentanone (29.42%), α-cedrol (26.98%), ∆3-carene (6.08%), and terpinen-4-ol (5.42%); the most OECs in the bark were di(2-ethylhexyl)phthalate (30.91%), cyclohexane (12.89%), caryophyllene oxide (8.90%), and α-pinene (4.59%). OECs of L. decidua wood were α-terpineol (26.06%), isoborneol (14.12%), camphene (11.78%), D-fenchyl alcohol (10.39%), and larixol (4.85%); OECs in the bark were larixol (33.29%), phthalic acid mono-2-ethylhexyl ester (16.96%), 13-epimanool (15.40%), and cyclohexane (8.44%).

An environmentally benign approach is put forward with the focus on directly liquefying and depolymerizing Cunninghamia lanceolata (Lamb.)Hook. (Chinese fir) sawdust into ethyl levulinate (EL) under supercritical ethanol (scEtOH) conditions by using phosphotungstic acid (PTA) as a catalyst. The effects of parameters such as catalyst dosage, temperature, and reaction time on alcoholysis yield were investigated. The experimental results show that the biomass alcoholysis yield reached 95.35% with 0.5 g PTA as a catalyst at 260 °C for 30 min. Alcoholysis yield and quantitative content of EL depended on the catalyst. The light bio-oil was primarily composed of phenols, aldehydes, ketones, and esters. A high quantitative content of EL up to 20.82% (AR, Relative abundance) was achieved, compared to 0.73% AR when PTA was not added. Hence, scEtOH with dissolved PTA may offer novel media for both chemical reactions and biomass conversion technology as a replacement for environmentally undesirable organic solvents.

In hydrogen peroxide bleaching of thermomechanical pulp (TMP), reaction temperature and time are the main factors that can improve the bleachability of pulp fibers. However, high temperatures can induce some problems such as cellulose degradation, yield loss, low fiber strength, and high environmental load. These negative effects of high temperature are mainly caused by radicals formed from the decomposition of hydrogen peroxide. To avoid the adverse effects of high temperature, we used two-step thermal treatments during hydrogen peroxide bleaching of TMP. The temperatures used in the two-step thermal treatments were 80 and 45 ˚C for a total bleaching time of 1 hour. In H2O2 bleaching of TMP, two-step thermal treatments were found to have had positive effects on the optical and physical properties of the pulp. The ISO brightness of the pulp bleached by two-step thermal treatments with hydrogen peroxide was identical to that of pulp bleached by conventional hydrogen peroxide bleaching. The post color number (PC number) of TMP was sharply increased after bleaching at 80 ˚C for 40 minutes. The post color number of TMP bleached by two-step thermal treatments is lower than that of TMP bleached by a one-step thermal treatment. The zero-span tensile index was also improved by two-step thermal treatments.