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Free formaldehyde is released due to the addition of aldehyde-based adhesives during the production of fiberboard. This is harmful to human health and pollutes the environment, and for that reason binderless fiberboard has become a research hotspot. There have been reports about pretreatments with white-rot fungi or lignocellulase to produce binderless fiberboard, but there have been no such reports about optimizing the bio-pretreatment conditions. In this study, poplar wood shavings were used for fiberboard production, and the bio-pretreatment conditions with Coriolus versicolor were studied using response surface methodology. After single-factor optimization, the central levels of bran, molasses, and magnesium sulfate were obtained. Further optimization was carried out using Box-Behnken design to study the influence of the factors. A second-order polynomial equation was obtained, and the low p-value (0.001) implied that the model was highly significant. The optimized bio-pretreatment conditions for modulus of rupture (MOR) of the fiberboard were obtained by ridge analysis as 3.021 g of bran, 8.907 g of molasses, and 0.27 g of magnesium sulfate. Under the optimized conditions, MOR of fiberboard reached 27.21±0.64 MPa, which was 2.2 times that of the control fiberboard. Bio-pretreatment with C. versicolor should be a good choice to produce a high-strength binderless fiberboard.

Binderless poplar powder compacts were prepared using the hot-pressing technology. The effect of the forming process on the mechanical properties and surface color of the poplar powder compacts was studied. The effect of forming temperature on mechanical properties and surface color was more noticeable than the forming pressure and the holding time. With the change of the forming process parameters, the static bending strength of the compacts increased first and then decreased. The overall change trend of the surface hardness increased continuously. The overall color difference (ΔE*) of the compacts increased with the change of forming process parameters and the surface color deepened gradually. The results of Fourier transform infrared (FTIR) spectroscopy showed that hemicellulose, cellulose, and lignin in the compacts were greatly affected by the forming process parameters. The degradation of hemicellulose and cellulose produced many colored substances, and the content of lignin increased. These made the surface color of compacts deepen. [ABSTRACT FROM AUTHOR]

As the worldwide demand for fuels and materials increases, fossil resources are decreasing and global warming is a concern, and thus the need for alternative solutions is high. In the industries of furniture and housing, particleboards are interesting materials, as they reutilize wastes from other industries (wood, agriculture) although they also rely on chemical binders that are petroleum-based and toxic. A very promising alternative is then clearly identified in finding ways to produce binderless boards and associated materials. This review considers the state of the art in the field of binderless board production, and other processes making it possible to turn raw plant fibers into structural materials without using any external chemistry. The mechanical properties and water resistance are collected and compared. Identified chemistry changes occurring during the thermo-compressive process are discussed with an aim towards understanding of the mechanisms of cohesion.

Wet-formed particleboard panels were made using cellulose nanofibrils (CNF) as the bonding material. The effects of panel density, CNF addition ratio, particle size, and pressing method on the nail and face screw withdrawal strength, water absorption (WA), and thickness swelling (TS) were investigated. The nail and face screw withdrawal strength increased with an increased panel density and CNF addition ratio. Mixed-size particles were favorable for better face screw withdrawal strength. The WA decreased while TS increased with increased panel density. The WA decreased with increased CNF addition ratio. The effect of CNF addition ratio on the TS was influenced by an interaction effect of the particle size, density, and pressing method. Smaller wood particles and the constant thickness (CT) pressing method were better for both WA and TS performance. All of the high- and medium-density panels failed to satisfy the standard requirements for face screw withdrawal strength. For lowdensity panels, those manufactured with mixed-sized particles all satisfied the standard requirements; those manufactured with large particles required at least 15% CNF to meet the standard, and those manufactured with small particles required at least 20% CNF to achieve the standard requirements. None of the panels met the standard TS requirement (< 8%). [ABSTRACT FROM AUTHOR]

Wet-formed particleboard bonded with cellulose nanofibrils (CNF) was prepared in this work. The effects of density, CNF addition ratio, pressing method, and particle size on the bending strength were evaluated. The results showed that density had the most important effect on the modulus of elasticity (MOE), while the CNF addition ratio had the most important effect on the modulus of rupture (MOR). For panels with low density (< 640 kg/m3), the MOE and MOR did not change much with the configuration changes between particle size and pressing method. This was due to the synergistic effect of incomplete compression and poor bonding in the core area using a constant thickness (CT) pressing method, and lower face density and higher core density using a constant pressure (CP) pressing method. For panels with medium density (640 kg/m3 to 800 kg/m3), the combination of larger particles, higher CNF addition ratio, and CT pressing method contributed to the highest bending strength. Further increase to high density (> 800 kg/m3), the pressing method's effect was more important, compared to panels with low and medium densities. With increased density and CNF addition ratio, panels were able to meet lowdensity and some medium-density standard MOE and MOR requirements. [ABSTRACT FROM AUTHOR]

The objective of the study was to investigate physical and mechanical properties of experimental particleboard panels manufactured from oil palm (Elaeis guineensis) biomass without using any adhesives. Different parts of oil palm, including the core and mid sections of trunks, fronds, bark, and leaves, were used to make the panels with an average target density of 0.80g/cm3. Based on the test results, it seems that panels made from bark and leaves did not have satisfactory strength and dimensional stability. However, the panels having particles from the core portion of the trunks exhibited the highest modulus of rupture and internal bond strength but lowest in thickness swelling and water absorption values among the samples. The panels made with particles of mid-section of trunks and fronds followed the samples having core portion trunks material. Three types of raw material, namely fronds, mid-, and core-parts of the trunks appeared as though they could have potential to manufacture particleboard panels with acceptable properties based on requirements stated in Japanese Industrial Standard (JIS). Similar to the above findings, surface quality of the samples were also found acceptable for the panels made from three types of particles. Based on the results of this work, oil palm in the form of biomass could be considered as an environmentally friendly alternative raw material to manufacture binderless particleboard panels.

As the worldwide demand for fuels and materials increases, fossil resources are decreasing and global warming is a concern, and thus the need for alternative solutions is high. In the industries of furniture and housing, particleboards are interesting materials, as they reutilize wastes from other industries (wood, agriculture) although they also rely on chemical binders that are petroleum-based and toxic. A very promising alternative is then clearly identified in finding ways to produce binderless boards and associated materials. This review considers the state of the art in the field of binderless board production, and other processes making it possible to turn raw plant fibers into structural materials without using any external chemistry. The mechanical properties and water resistance are collected and compared. Identified chemistry changes occurring during the thermo-compressive process are discussed with an aim towards understanding of the mechanisms of cohesion. [ABSTRACT FROM AUTHOR]

Pressing beech veneers at high temperatures has been shown to be a reliable method for manufacturing laminated boards without adhesives. The reasons behind the self-bonding phenomenon as well as the causes of the waterproof character gained by the boards being pressed at 250 °C were investigated. Water leachates from the dried and the hot-pressed veneers were analysed by UV-spectroscopy, high-performance liquid chromatography (HPLC), and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR). Press-plate temperatures during hot pressing were 200, 225, and 250 °C. After pressing, an increased content of 5-(hydroxymethyl)furfural (not at 250 °C) and conjugated phenols was observed in the bonding lines (interfaces) compared to the inner part of veneers of the self-bonded boards. Furfural contents were low and relatively similar, but 5-(hydroxymethyl)furfural (HMF) showed an abrupt decrease in the bonding line when the temperature increased from 200 °C to 225 °C and especially to 250 °C. The contribution of caramelization to browning and bonding is suggested. In studies with CP/MAS 13C NMR, a higher content of phenolic units in beech lignin was observed during hot pressing at 225 °C. Homolytical cleavage of β-O-4 structures in lignin as well as the condensation reactions involved are discussed. [ABSTRACT FROM AUTHOR]

Utilization of oil palm trunk waste for production of environmental friendly binderless particleboard was studied. Response surface methodology was used to optimize the manufacturing conditions. The steaming temperature (100 to 120°C), steaming time (25 to 50 min), hot pressing temperature (180 to 220°C), and hot pressing time (15 to 30 min) were optimized in the ranges shown. The optimum conditions for making the particleboard were found to involve steaming for 46 min at a temperature of 120°C before it was compressed using a pressure of 12 MPa, at a temperature 215 °C for 29 min. The internal bond (IB) strength, modulus of rupture (MOR), thickness swelling (TS), and water absorption (WA) were 0.54 MPa, 8.18 MPa, 22%, and 51%, respectively. The residual values of actual and model-based calculated IB, MOR, TS, and WA were found to be 0.1 MPa, 0.23 MPa, 2%, and 4%, respectively, which shows the significance of the study. [ABSTRACT FROM AUTHOR]

The objective of the study was to investigate physical and mechanical properties of experimental particleboard panels manufactured from oil palm (Elaeis guineensis) biomass without using any adhesives. Different parts of oil palm, including the core and mid sections of trunks, fronds, bark, and leaves, were used to make the panels with an average target density of 0.80g/cm³. Based on the test results, it seems that panels made from bark and leaves did not have satisfactory strength and dimensional stability. However, the panels having particles from the core portion of the trunks exhibited the highest modulus of rupture and internal bond strength but lowest in thickness swelling and water absorption values among the samples. The panels made with particles of mid-section of trunks and fronds followed the samples having core portion trunks material. Three types of raw material, namely fronds, mid-, and core-parts of the trunks appeared as though they could have potential to manufacture particleboard panels with acceptable properties based on requirements stated in Japanese Industrial Standard (JIS). Similar to the above findings, surface quality of the samples were also found acceptable for the panels made from three types of particles. Based on the results of this work, oil palm in the form of biomass could be considered as an environmentally friendly alternative raw material to manufacture binderless particleboard panels. [ABSTRACT FROM AUTHOR]