Volume 13 Issue 3

Elongation is an important property of many packaging board and paper grades. Paper with high extensibility could provide an alternative for oil-based packaging materials. Micro- (CMF) and nanofibrillated (CNF) cellulose are known to increase the strength of a paper, but their effect on the drying shrinkage and elongation is not well-studied. In this work, paper was reinforced with fibrillated material. Added fibrillated material increased the drying shrinkage, which was generally proportional to the increase of paper elongation before breakage. Results differed depending on the fibrillated material and how it was added to paper (wet-end addition or spray application). The papers were dried unrestrained in order to achieve the highest elongation potential for the paper. Spray application of CMF increased elongation by 13%, while wet-end additions increased elongation by 20% and also strength by 10%, but only with high dosages. Spray application of oxidized-CNF improved elongation by 33%, while wet-end applications increased only strength by 20%. Thus, boosting the drying shrinkage with fibrillated cellulose is one potential way to increase elongation and 3D formability of paper.

The interlaminar shear stresses of the three-layer, five-layer, and seven-layer cross laminated timber (CLT) and those of the oriented laminated beams were calculated according to Hooke’s law and the differential relationship between the beam bending moment and shear force. The interlaminar and maximum shear stresses of the CLT beam are related to the number of CLT layers and to the elastic modulus ratio E_L/E_T (or E_L/E_R) of the parallel and perpendicular layers. The interlaminar shear strength of the Hemlock CLT was positively correlated with the elastic modulus of its parallel layer. The results showed that the CLT short-span beams had three failure modes when subjected to a three-point bending test, namely perpendicular layer rolling shear failure, CLT interlaminar shear failure, and parallel layer bending failure. The shear stress of the oriented laminated beam followed a parabolic distribution along the height of the section, while the shear stress of the orthogonally laminated beams tended to be balanced, rather than parabolically distributed along the height of section. The short beam three-point bending method was able to effectively test the interlaminar shear strength of CLT due to its stable and readable load.

Formable papers can be used as an alternative to rigid plastics for making 3D shapes for packaging applications. However, commercial use of formable paper is currently limited, due to its poor extensibility. Cellulosic fibres can be combined with polyurethanes to improve the deformability of resulting fibre-polymer composites. This work describes the effect of spray and wet-end addition of polyurethane dispersions to paper to enhance the extensibility and formability of paper. The increase in extensibility was directly proportional to the amount of polyurethane retained in the paper. Absolute improvements in extensibility were as high as 4 to 6 percentage points. Improved extensibility resulted in better formability of paper, which eventually could allow it to compete with plastic packaging in certain applications.

A strategic method that utilizes the co-culture of Clostridium thermocellum ATCC 27405 and Thermoanaerobacterium thermosaccharolyticum DSM 571 was developed to improve the ethanol yield from the thermophilic fermentation of Salix. The co-culture conditions of the two strains were optimized using single factor and response surface experiments to enhance the ethanol yield. An even higher ethanol yield was obtained under the optimum co-culture conditions in fermenter tanks than what was observed in pre-experiments in serum bottles. The maximal ethanol concentration and yield were 0.2 g/L and 11.1%, respectively, and with a 26.4% cellulose degradation ratio and 13.8% hemicellulose degradation ratio when the pH was kept stable at 7.0 in fermenter tanks.

The aim of this work was to investigate the influence of sample preparation including variation in moisture content and particle size on the accuracy of near infrared (NIR) spectroscopy models developed to predict Klason lignin, total lignin, and holocellulose in wood. Seventy-five samples of sawdust obtained from a eucalyptus plantation were divided into aliquots and submitted to three different treatments: traditional (TRAD), large particle dried at room temperature (LPRT), and large particle oven-dried (LPOD). The influence of sample preparation method on models’ accuracy was compared by statistical analysis. Overall, grinding to a larger particle size and drying at room temperature (treatment LPRT) did not decrease the accuracy of the prediction models when compared to the TRAD sample preparation method. These findings were more evident for Klason lignin and holocellulose. This is relevant because resources used for sample preparation (i.e. grinding and drying) can be minimized, which is expected to reduce the costs associated with analysis of wood properties by NIR.

In the authors’ previous studies, a bleaching process based on continuous chemical supplementation (CCS) was proposed to improve the effectiveness of peroxide bleaching of chemi-thermomechanical pulp (CTMP). In this study, the kinetic model of the CCS process of peroxide bleaching was applied to poplar CTMP to explore how the bleaching rate was affected. The model was based on the rate of chromophore elimination characterized by the brightness gains of bleached pulp. The reaction rate of chromophore destruction proceeded via a rapid initial phase followed by a slow phase. The equation of reaction rate was confirmed. The value of reaction order was -3.62, and the activation energy was 288.8 kJ/mol. The developed kinetic model was a good fit for the experimental results.

Furniture must be designed to suit the intended use. Producers need to guarantee its quality and stiffness. During external loading, there are internal forces that can be transmitted and may result in a failure. This article examines the dowel joint, which is one of the most popular furniture joints. It discusses the effects of selected parameters, such as type of loading (tension and pressure), the size of the dowel (one-half or one-third of the joined parts), wood species [beech (Fagus sylvatica L.) and spruce (Picea abies L.)], and the adhesives type (polyvinyl acetate and polyurethane), on the joint stiffness. The effect of the annual rings was also monitored; however it was not determined as significant. Based on the results, the dowel joint is recommended with greater diameters and while using PVAc gluing. Article also deals with test simulation in virtual environment using the programme Solidworks.

Biogas projects are rapidly expanding in China, but there is insufficient cropland to degrade these biogas residues. Mushroom cultivation has been used to degrade various agricultural wastes. In this study, to screen the feasibility of utilizing biogas residues as potential substrates for the cultivation of Pleurotus ostreatus, seven different concentrations (0 to 60%) of biogas residue mixed with cottonseed hull, wheat bran, and lime were used to cultivate P. ostreatus. The mycelial growth rate, mycelial colonization time, yield, biological efficiency, chemical compositions, and content of four heavy metals, Cd (cadmium), Pb (lead), Hg (mercury), and As (arsenic), were analyzed. The results showed that 10 to 30% of biogas residue mixed in the substrates induced the growth of P. ostreatus mycelia faster than the others. A lower percentage (10 to 20%) of biogas residue added to the substrates is beneficial to the production and nutrient components of P. ostreatus, and the fruiting bodies produced on biogas residue-containing substrates conform to the safety standards for edible mushrooms. Although the total harvest is not significantly increased when biogas residue is added, the utilization of cheap biogas residues can conceivably reduce the practical cost and benefit the environment.

Biomass chars (bio-chars) prepared under two pyrolysis modes and with four particle size ranges were investigated. The pyrolysis modes included isothermal pyrolysis and non-isothermal pyrolysis with three heating rates (5 °C/min, 10 °C/min, and 15 °C/min). The particle size ranges were 58-75 μm, 75-106 μm, 106-150 μm, and 150-270 μm. The pyrolysis characteristics, pore structures, surface morphologies, and functional groups of the bio-chars were characterized by TGA, specific surface area and porosity analyses, SEM, and FTIR. The mercury adsorption was further explored by the adsorption kinetics. The results established the optimum pyrolysis conditions for mercury adsorption: pyrolysis temperature of 600 °C, heating rate of 10 °C/min, and particle size of 58-75 μm. In addition, the mercury adsorption processes were affected by both physical adsorption and chemical adsorption. Furthermore, the rate constants of the pseudo-first-order and pseudo-second-order models gradually increased with decreasing particle size.

An in-situ observation on the morphological behavior of bamboo’s fiber-foam composite structure under flexural stress was conducted, and the respective contribution of parenchymatous tissues and sclerenchyma fibers to the flexural ductility of bamboo was evaluated. Fibers or parenchymatous cells at the bottom suffered tensile stress during bending process, where initial microcracks occurred. The results suggested that the bottom parenchymatous tissues experienced a perforative tear along the loading direction, while fibers continued to stretch until several fibrous tensile failure cracks were observed. The subsequent crack growth mode was similar to that of the horizontal crack transmission that began when it reached fibers or somewhere between fibers, until another weak load-bearing point appeared, and then it expanded up through parenchymatous tissues. As a whole, the crack acted ladder-like in its growth, and the propagation paths were not restricted to a coherent one. Images of the morphological changes of the upper parenchymatous tissues and sclerenchyma fibers, which suffered compressive stress during bending process, indicated that parenchymatous tissues and sclerenchyma fibers made different contributions to the flexural ductility of bamboo. Sclerenchyma fibers supplied deformation resistance for bamboo’s macroscopic deformation, while parenchymatous tissues offered deformation space due to the variation of cellular morphology and location.