Volume 18 Issue 4

This article analyses high-consistency pulp refining using a disk refiner. During the experiment, the size of the gap between the rotor and stator cutters (0.5 to 1.5 mm), rotor speed (2,000 to 2,500 rpm), pulp consistency (10 to 20%), and freeness value (15 to 60 °SR) of the pulp were varied. The refining results were characterised by changes in 10 output parameters: morphological properties of cellulose fibres (average length, width, fibrillation index, water retention value, average kink angle, and coarseness) and the physical and mechanical characteristics of handsheets (breaking length, bursting strength, tearing resistance, and folding endurance). A total of 56 observations were made on the samples. Factor and cluster analysis methods were used to study the structure of correlations between the output parameters. More than 96% of the total dispersion of all output parameters was due to a change in two latent (hidden) factors: the first one was responsible for 79.6% of the dispersion and is presumably identified as the degree of external fibre fibrillation and the second one (16.6% of the dispersion) as fibre flexibility (including coarseness and average kink angle).

Literature is limited regarding the potential use of the bark of Maclura pomifera as a source of bioactive compounds. The influence of different extraction methods was assessed for the chemical and biological properties of extracts obtained from the bark and periderm of M. pomifera. The extraction process was completed using three methods: microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and sonicator-assisted extraction (SAE). The extracts were characterized by total polyphenol content. The antioxidant capacity was evaluated using DPPH and ABTS methods, the antimicrobial effect was tested against Gram-positive and Gram-negative bacterial strains, and the inhibition of enzyme activity was conducted using α-glucosidase, lipase, and α-amylase assays. The extracts obtained from the periderm exhibited a lower total polyphenolic content compared to those obtained from the bark. The highest antioxidant activity using the DPPH method was observed in the MAE bark extracts and when using the ABTS method, and the highest activity was observed in the UAE bark extracts. Enzymatic activity was most strongly inhibited by the SAE bark extract. The most pronounced antibacterial potential was observed in the MAE and UAE bark extracts, with minimum inhibitory concentration values obtained below 1 mg/mL.

Due to the complex motion state of biomass raw materials in the granulation process of involute plunger biomass ring mold granulator, it is difficult to analyze by use of a linear mechanical model. Accordingly, a granulation simulation model of molded parts was established by coupling discrete element (DEM) and finite element (FEM) analyses. The stress and strain results of ring die and involute plunger pressure roller were analyzed. On this basis, it can be predicted that for wood pellet materials, when the pressure angle of the involute plunger involute profile is 20°, the ring mold forming hole length-diameter ratio is 4.5, the forming hole diameter is 8 mm, and the hole cone angle is 90°, the compression force on the wood pellet will be maximized at 7.89 KN, the maximum equivalent force at the ring mold forming hole and the root of the involute plunger pressure roller will be 64.2 and 84.5 MPa, respectively, and the maximum deformation will be 0.000327 and 0.000424 mm, which is within permissible limits. The involute plunger roller is more susceptible to fatigue damage compared with the ring die. By contrast, the ring part is more prone to fatigue damage in the case of a ring die.

The building sector has seen recent growth in the number of published environmental product declarations (EPDs). EPDs share environmental data of construction materials, which can help building practitioners prioritize products with lower environmental impacts. However, EPDs rely on varying assumptions within their life cycle assessment (LCA). This study aimed to evaluate the use of EPDs as a data source instead of a generic data source and its effect on the life cycle impacts of a multi-residential building. This study focused on 19 North American EPDs of structural wood products. The impact assessment results found in the EPDs were compared to the Ecoinvent V3.8 database. The findings of the present study suggest that EPDs can generally be used without distinction compared to the data in the Ecoinvent V3.8 database. However, a few data were found to be outliers. In addition, EPDs of structural wood products only disclosed its manufacturing stage. Other life cycle stages, such as transport of the construction product, can have a significant impact on the building’s LCA. Therefore, using EPDs to assess building impacts is recommended over their direct comparison for practitioners to make more comprehensive decisions towards embodied impacts of buildings.

Thermal modification of wood changes its chemical, physical, and structural properties, which may affect adhesive bondline quality and bonding performance. This research compared the effect of thermal modification on the adhesive bonding performance of poplar (Liriodendron tulipifera) wood. Samples were prepared from thermally modified and unmodified yellow poplar using one-component polyurethane (PUR) and polyvinyl acetate (PVA), as they are adhesives used in wood products. Microscopic properties of the bondlines were investigated to understand shear performance and durability. Adhesive line thickness, penetration, shear strength, and moisture durability were measured, and failure modes were recorded. Thermal modification negatively affected the wood and adhesive interaction by reducing penetration (31.2% in PUR and 29% in PVA), therefore creating a thicker adhesive line (70% in PUR and 2% in PVA) and consequently causing a significant reduction in the shear strength of both adhesive types (27% in PUR and 36% in PVA) compared with non-modified specimens. The PUR adhesive had higher shear strength than PVA by 2.7% in non-modified and 14% in thermally modified wood.

This paper focuses on estimation of shives(wide) and fiber length in RGP82CD-refiners using an AutoRegressive eXogenous (ARX) structure in a data-driven soft sensor concept. Both external and internal variables are considered as model inputs. The pulp properties were sampled every 15 min from an on-line device positioned after the latency chest, whereas other process data were sampled every 6 seconds. Notably, despite the high data sampling rate, the development of robust models necessitated a dataset spanning over two months of process information. The external variables studied in this paper were specific energy, the sawmill chip content, plate gaps, and dilution water feed rates to each refining zone. Additional internal variables, such as the inlet flat zone temperature, the maximum temperature, and the periphery temperature in the conical zone, were also used as model inputs. It was concluded that both shives(wide) and fiber length can be estimated with relatively good accuracy although large uncertainties exist in the measured properties. Finally, it was shown that fast pulp property dynamics in the blow-line can be followed, which outperforms current practices of using pulp measurement devices positioned after the latency chest. This offers implementation of more advanced future pulp property control concepts.

Management of forest carbon sinks can be viewed as a strategy to deal with climate change. To promote the establishment and improvement of the forest carbon market, it is important to measure the economic benefits of China’s existing forest carbon sinks with special weighting to forests along with protection of nature. Objectively measuring the value of a carbon sink is an important prerequisite to play the role of forest carbon pool and improve the efficiency of carbon sinks. This paper considers the strategy and process of forest carbon sink value accounting from two aspects of forest carbon storage and value, puts forward a set of forest carbon sink fair value accounting ideas, and considers Yixing forest farm as the research area. The following methods were used to compare the forest carbon stock of the Yixing National Forest Park. First, the economic benefits of forest carbon sink were evaluated with a market approach and carbon fair value. Next, the biomass expansion factor method and income approach were used to compute the forest carbon stock of Yixing National Forest Park, indicating a high carbon fair value.

Taking the conventional drying process of Pinus sylvestris square wood with pith as the research material, based on the Back Propagation (BP) neural network algorithm, a model was constructed using the real-time online-measurement data. Softening treatment time and temperature, variable treatment time and temperature, initial moisture content of wood, and position of wood core and sapwood were used as model inputs. Wood drying rate and longitudinal cracking degree were used as outputs to indicate wood drying quality. The results showed that with a suitable model structure of 6-9-2 (input layer-hidden layer-output layer), the coefficient of determination R² and mean square error of the test samples were 0.96, 0.99, and 0.00605, respectively, indicating that the neural network model has good generalization ability. Compared with the experimental value, the predicted value basically conforms to the change law and size of the experimental value, and the error distribution is approximately 2%. This shows that the BP neural network model can simulate the drying rate and longitudinal cracking degree in the drying process and realize the prediction of the drying process.

The structural changes of cellulose in non-solvent liquid media can provide insights into the high-value utilization of cellulose. This study includes molecular dynamics simulations of 36-chain cellulose Iβ microfibril model (Iβ-MF) behavior in 16 non-solvent liquids with different polarities at room temperature using two carbohydrate force fields (CHARMM36, GLYCAM06). Iβ-MF in CHARMM36 retains more than 70% of the tg conformation in 16 liquids, and the retention of the tg conformation increased with decreasing liquid polarity. Liquid polarity can affect the hydroxymethyl conformation of cellulose, which is only an appearance, and the real driving force behind is the electrostatic interaction between liquid molecules and cellulose. Furthermore, changing the 1,4 electrostatic scaling factor of GLYCAM06 can effectively affect the structural convergence of Iβ-MF. The Iβ-MF forms an alternating layer structure in the gg/gt conformation in a medium to high polarity non-solvent liquid, while the model undergoes untwisting. Model untwisting is inextricably linked to the degree of alternate layer structure formation. This paper provides a theoretical basis for the molecular study of nanocellulose structures from an energy-structure-property perspective.

Various methods exist for surface decoration of wood-based panels, with decorative plastic film emerging as a primary choice due to its environmental friendliness, design versatility, and ease of processing. To leverage the benefits of film-laminated wood-based panels, this study explored a research and development (R&D) strategy for customized kitchen cabinets made from these panels by the integration of the Quality Function Deployment (QFD) and the Analytic Hierarchy Process (AHP) approaches.  AHP was employed to construct a hierarchical model of user requirements. Utilizing QFD, user requirements were translated into technical characteristics, and their degree of importance were determined, which facilitated a precise understanding of the technical priority.  Study findings indicated that user requirements for film-laminated wood-based panels prioritized practicality, safety, appearance, and durability. The AHP-QFD model employed mathematical methods to establish a connection between the user and technical levels, so as to excavate the focus and direction of the process flow from the preparation of the material to the design and manufacture of the product, and to provide a reference for the future application of similar environmentally friendly materials.