Volume 9 Issue 4

In this study, water absorption and desorption behaviors of wood-plastic composites (WPCs) treated with ultraviolet agents and zinc borate were investigated. Water diffusion characteristics in the composites were analyzed using a one-dimensional diffusion model. The mechanism of water sorption for all composites deviated from Fick’s law of diffusion. Much larger diffusion coefficient values are observed from the desorption process when compared to the absorption process. Measured final equilibrium moisture content and calculated diffusion coefficients varied with sample formulation in a non-consistent manner; this indicated that the durability treatment used in the current study did not negatively affect the water sorption behavior of WPCs. The results of this study help to clarify the effect of durability treatment on the dynamic moisture sorption process of WPCs.

To predict the resin absorbing content of bamboo bundle fiber, a model relating to the soaking time and mass ratio of polyvinyl acetate (PVAC) adhesive to phenol formaldehyde (PF) resin defined on the basis of the Lucas-Washburn equation was proposed. Various dipping times and different PVAC/PF ratios were investigated in the experiment. Variance analysis revealed that the resin absorbing content was significantly associated with the ratio of PVAC/PF. However, the soaking time had a significant effect on bamboo fiber resin absorbing content from 0 s to 70 s and had an insignificant effect after 70 s. The results showed that the model proposed could accurately predict the resin absorbing content for bamboo bundle fiber impregnated in different PVAC/PF levels. The comparison of theoretical calculations with experimental results revealed that the residual sum of square and root mean squared error were relatively low, and the correlation coefficients and coefficients of determination were all over 0.95.

Previous attempts have already been performed for the production of sugars and, later, bioproducts from orange peel using different Trichoderma reesei commercial cocktails in combination with other kinds of enzymes. In this study, the feasibility of simple pretreatments combined with enzymatic treatments was compared between grapefruit inner peel (GFIP), orange inner peel (OIP), grapefruit whole peel (GFWP), and orange whole peel (OWP). The four biomaterials were characterized with respect to the contents of cellulose and hemi-cellulose, elemental analysis, and Fourier transform infrared (FTIR) spectrometry. The 3,5-dinitrosalicylic acid assay demonstrated that GFIP and OIP produced 31.7% and 34.9% more reducing sugar than GFWP and OWP, respectively. Further investigation of the bioprocess showed the optimal conditions include the following: (i) a solid to liquid ratio of 4%, (ii) enzymatic activity of 0.075 U/mL, and (iii) reaction at 55 °C and a pH of 5.0. Moreover, the major products after cellulolytic hydrolysis were fructose, glucose, and cellobiose. This study provides an alternative and effective approach to extend the utilization of agricultural waste in the fields of food and energy.

There are different reasons for planing timber. One is to adjust the cross-sectional dimensions of thickness and width. Another is to adjust the timber’s outer shape, usually in order to reduce warp resulting from drying and having the forms of cup, twist, bow, and crook. The end-result depends on the properties of the timber before planing and on the planer design and settings. In the present work it was found that increasing or decreasing the forces exerted on the timber by a four-sided planer does not affect the cutting depth or the twist reduction. The pressure settings do not affect the rectangularity or the amount of unplaned areas on the surfaces either. The possibility to impact the result with this type of planer, apart from the cutting depth and planed dimensions, is slim to none.

Lime sludge is a special type of precipitated calcium carbonate (PCC) recovered from black liquor, which can be used as paper filler in the paper-making process. However, one of the biggest problems when lime sludge is used as filler is that it is difficult to hydrophobically size the filled paper, especially in the case of paper with high filler content. Also, the efficient retention of the sizing agent AKD is a fundamental requirement for effective paper hydrophobic sizing. Therefore, in this work, a ternary retention aids system, cationic starch/CPAM/bentonite, was applied, and the hydrophobic sizing degree of lime sludge filled paper sheets and filler retention were evaluated. The results showed that the retention of lime sludge was significantly influenced by CPAM and was overall increased as the dosage of CPAM increased; cationic starch showed a more significant influence on paper Cobb value than filler retention; relative lower Cobb values and higher filler retention were achieved at lower bentonite dosage. At 0.75% cationic starch, 0.043% CPAM, and 0.3% bentonite, a substantial high hydrophobic sizing efficiency of Cobb value (45.72 g/m2) and filler retention (80.37%) were achieved simultaneously due to the synergetic performance of a cationic starch/CPAM/bentonite retention aids system.

This paper describes the analysis of raw wood flows in Slovakia. Material flow analysis was used to reveal and quantify relations between the resources and the primary uses of wood. In particular, two approaches to wood flow modelling were utilised – wood balance and wood resource balance. Wood balance was introduced to illustrate a global view of the resources and primary uses of roundwood in Slovakia without analysing internal flows or individual roundwood assortments, respectively. The wood resource balance, as a more detailed analysis, takes into account the uses of wood as a material and also the by-products and waste generated by the production that could be used as inputs for further uses in wood processing or energy sectors. The latter balance was compiled using available official statistics supplemented by a questionnaire to estimate missing data for waste streams. With a total consumption of 11.964 mil. m³ roundwood equivalents, the value of the overall cascade factor was 1.11. Over 84% of all resources were used for industrial purposes, and nearly 16% were used for energy generation.

This study compared and characterized slicewood acetylation with acetic anhydride using conventional liquid phase, microwave, and vapor phase reactions. The results revealed that there were no significant differences in the flexural properties between the unmodified and acetylated slicewood, regardless of the reaction method used. Furthermore, findings concluded that the slicewood acetylated with a vapor phase reaction required less modifying agent to achieve high levels of weight percent gain (WPG). The correlations between the anti-swelling efficiency (ASE) and the WPG of the slicewood acetylated with a vapor phase reaction were higher than the conventional liquid phase and microwave reactions. The reactivity of the cellulose hydroxyl groups was sensitive to the C2 and C6 reactive sites for all three acetylation methods. However, the reactivity was more pronounced at the C2 position with a vapor phase reaction compared to the other two reactions. Nevertheless, slicewood acetylation with acetic anhydride was found to not have a significant influence on viscoelastic properties for any of the different reaction methods.

In this study, crude lignin extracted from the black liquor generated by a pulp and paper mill was modified by different doses of irradiation. The crude and irradiation-modified lignins were used to treat wastewater that was generated during the production of starch glucoamylase. Changes to the physical and chemical properties and structure of the irradiation-modified lignins were determined using scanning electron microscopy, solubility analysis, elemental analysis, analysis of phenolic hydroxyl group, ultraviolet–visible spectroscopy, and Fourier transform infrared spectroscopy. Irradiation reduced the phenolic hydroxyl content in the lignin but increased its solubility by about 40%; analysis revealed that irradiation also destroyed the skeletal structure of the benzene ring in the lignin. After four minutes of settling, the total nitrogen (TN) and chemical oxygen demand (COD) in the wastewater reached 7.0 mg/L and 1573.1 mg/L, respectively. The settled solids content and protein recovery were 1.12 g/L and 98%, respectively. This study suggested that irradiation-modified lignin extracted from black liquor generated in the pulp and paper industry can be used to treat wastewater from the production of starch glucoamylase.

One of the biggest disadvantages of wood, as a potential reinforcement for thermoplastics, is its hydrophilicity. The aim of this study was to evaluate the effect of chemical modification of wood flour on mechanical, thermal, and fire properties of filled high-density polyethylene composites. For this purpose, aspen flour was modified with maleic, propionic, and succinic anhydrides. The modified wood flour and high-density polyethylene were compounded into pellets by single-screw extrusion, and test samples were prepared by injection molding. Tensile and flexural tests, impact testing, limiting oxygen index, TGA, and SEM analyses were conducted both for modified and un-modified samples. Based on the test results, chemical modification enhanced the properties of thermoplastic composites. Depending on the chemical concentrations, the flexural, tensile, and impact strengths of the modified flour filled HDPE composites were improved slightly, while the tensile and flexural moduli of the samples were increased significantly. The limiting oxygen index (LOI) levels of samples with modified wood flour were slightly improved, and succinic anhydride provided higher LOI levels compared to the samples with other anhydrides. This showed that the composites filled with chemically modified wood flour were slightly more thermally stable than control samples. It appears that wood flour modified with maleic, propionic, and succinic anhydrides can be successfully utilized as filler in polymer matrices.

Cellulose fibres were treated with sodium hydroxide (NaOH) to improve the accessibility of chemical reagents and the roughness of fibre surface at low temperatures. The accessibility, supermolecular structure, morphology, and physical properties of fibres were investigated using solid-state cross polarisation/magic angle spinning 13C nuclear magnetic resonance (CP/MAS 13C NMR), wide-angle X-ray diffraction (WAXD), and scanning electron microscopy (SEM). The results showed that in low temperature (-16 °C), the iodine sorption value of cellulose fibres is 145.2 mg. The shift from the C6 signal of the molecular structure to the amorphous area indicated a decrease in the crystallinity of the material from 66% to 8%, and the transformation from cellulose I to II occurred. The SEM revealed fold shapes in the fibre surface, which increased the fibre surface area.