Lower Thickness Swelling Research Articles

Coniferous Bark as Filler for Polylactic Acid-Based Biocomposites.

This study explores the possibilities of utilisation of coniferous bark as a filler in wood-polymer composites (WPCs), its impact on properties such as the modulus of rupture (MOR), modulus of elasticity (MOE), thickness swelling (TS) and water absorption (WA) after 2 h and 24 h of immersion in water and the significance of this impact compared to other factors. Six variants of bark-polylactic acid (PLA) WPCs were manufactured, differentiated by their filler content and filler particle size. As a comparison, analogous composites filled with coniferous sawdust were also manufactured. Bark-filled composites were characterised by lower TS and WA after both 2 h and 24 h of immersion, as well as lower water contact angles and surface free energy. The bark filler decreased the composites' MORs and MOEs, while greater differences were noticed for variants filled with small particles. The type of filler was the second most important factor contributing to variance in this study, with the filler content being the most important one.

Hydrolytic Stability of Sengon-Oriented Strand Board Bonded with Hybrid Phenol-Formaldehyde/Polymeric Methylene Diphenyl Diisocyanate Adhesives

The hydrolytic stability of oriented strand board (OSB) is critical to guarantee good performance in humid conditions over the long term. The adhesive system impacts hydrolytic stability in addition to the wood strands. This study aims to investigate the hydrolytic stability of OSB bonded with a hybrid adhesive based on phenol-formaldehyde (PF) and polymeric methylene diphenyl diisocyanate (pMDI) modified with NaOH and CaCO3 catalyst. PF was mixed with each catalyst at approximately 1% of the PF solids content. The pMDI was added to the mixture at 2.5% and 5% of the PF solid content. The hybrid PF/pMDI adhesives were then used for OSB production. The hydrolytic stability of OSB samples was tested at 25°C and 100°C and compared with OSB using unmodified PF as a control. After hydrolysis, OSBs with hybrid PF/pMDI adhesives had lower weight loss than control adhesives at both temperatures. The pH indicates no significant polymer dissolution from the board into the hydrolysis solution. Hybrid PF/pMDI adhesives with a CaCO3 catalyst obtain significantly lower thickness swelling values. The findings of this study have significant implications for developing high-performance, environmentally-friendly OSB products. Keywords: eco-friendly composite, hydrolytic stability, oriented strand board, Paraserianthes falcataria, phenol-formaldehyde

Activated Carbon from Coconut Shells as a Modifier of Urea–Formaldehyde Resin in Particleboard Production

Various methods for the effective modification of urea–formaldehyde (UF) adhesives, aimed at enhancing the performance of wood-based materials, have been continually explored worldwide. The aim of this work was to investigate and evaluate the effect of introducing small amounts (0.25–1.5%) of activated carbon from coconut shells (ACCS) in UF adhesive on the properties of particleboard. The performed investigations of the adhesive mixture’s properties showed an increase in both viscosity and reactivity. Moreover, the use of loadings of 0.75% and 1% had a positive effect on mechanical properties such as bending strength, modulus of elasticity, and internal bond. In these variants, a delay in the degradation of the adhesive bonds by water was also observed, as indicated by the lower thickness swelling values measured after 2 h. However, under long-term exposure to water, the modification had no considerable effect on the dimensional stability of the boards. Markedly, the addition of 1 and 1.5% of ACCS resulted in a reduction in formaldehyde content, which can be attributed to the excellent adsorption capacity of activated carbon. Overall, a loading of 1% was found to be optimal, resulting in improved strength, enhanced water resistance, and reduced formaldehyde content.

Dimension stability, tensile and thermomechanical properties of bamboo/oil palm fibre reinforced bio-epoxy hybrid biocomposites

The rising liability to suffer the environment eco-friendly covers the approach to the improvement of materials with bio-natural wastes. This research experimentally aims to study bamboo/oil palm reinforced bio-epoxy hybrid composite. Bamboo (B) and oil palm (O) reinforced bio-epoxy was fabricated as a control. The fabricated biocomposites were characterised by mechanical properties (tensile tests), physical characterisations (density, water absorption (WA) and thickness swelling (TS)), thermomechanical analysis (TMA), and morphological (scanning electron microscopy (SEM)). Among the hybrid composites, 5B5O has the highest tensile strength and modulus which is 35.66 MPa and 4.95 GPa, respectively. Based on the findings, the physical properties, WA and TS capacities (WA and TS) of B and 3B7O biocomposites were increased compared with all corresponding biocomposites while the O biocomposite exhibited lower TS and WA values compared to other samples. The hybrid 3B7O biocomposite sample was attributed to a higher void percentage (6.29%) and lower density (1.25 g/cm3) compared to other biocomposites. Generally, the SEM analysis of hybrid biocomposites confirms a valuable interaction between the filler and the matrix as further penetration for the matrix was permitted into the greatly porous structures of natural fibres. Furthermore, the SEM test of the fracture point confirmed the observations from the mechanical properties. The obtained findings confirmed that hybrid fibres improve the properties of the bio-epoxy matrix and can be utilised as sustainable and renewable biocomposites for several applications such as automotive tools, furniture and medical tools.

Utjecaj predimpregnacije anhidridom octene kiseline i vremena zagrijavanja na mehanička i fizička svojstva drvno-plastičnih kompozita

This research aimed to assess the influence of different pre-impregnation times (PITs) (60, 180, and 300 min), heating or reaction times (H/RTs) (60, 90, and 120 min), and chemical modification of wood flour (WF) on the mechanical and physical properties of wood-plastic composites (WPCs). The study employed acetylated beech (Fagus orientalis L.) flour as the filler and polypropylene (PP) as the matrix phase producing of WPC samples through melt compounding and injection molding. The resulting composites underwent testing for their physical and mechanical properties. The findings revealed that WPCs derived from acetylated wood with PITs of 60 min and H/RTs of 60 min exhibited the highest mechanical properties, except for the bending modulus. Moreover, the lowest water absorption (WA) was observed in the PITs-H/RTs combination of 60-120 min, while the lowest thickness swelling (TS) occurred in the PITs-H/RTs combination of 300-60 min. The simultaneous utilization of pre-impregnation and reaction times demonstrated a synergistic effect on the physical and mechanical properties. Consequently, the chemical modification of wood flour and the application of suitable reaction times improved the interfacial adhesion, thereby enhancing the overall performance of the WPCs.

Melamine Acetate Preparation as a Urea-Formaldehyde Resin Additive for Particleboard Production

Urea-formaldehyde (UF) resin binders for wood-based panel production often use melamine as an additive to improve both mechanical properties and environmental compliance. Direct fortification for efficient use of melamine remains a problem due to low solubility. Pizzi & coworkers suggested the use of more soluble melamine salts and demonstrated success in terms of product performance. However, their preparation method showed low productivity and inefficient use of material and energy. In their scheme, a batch reactor fed with 1 kg of water and 75 g of a stoichiometric amount of melamine and acetic acid produced only around 25 g of solid melamine acetate crystal. In contrast, the remaining 50 g remained dissolved in 991 g of water, which requires high of energy to evaporate. This paper reports an attempt to increase batch productivity and work towards the more efficient use of material and energy. The experiment showed that the successive addition of melamine and acetic acid to the batch up to the solubility limit of melamine at the same reaction condition increased melamine and acetic acid fed from 75 g to 165 g. This was followed by a significant increase in dry crystal yield from 25 g to 117 - 132 g. Feeding the mother liquor to the next batch decreased the water use to only 8% of the original requirement. This resulted in a highly efficient process, eliminating the need for energy-intensive melamine acetate recovery from the mother liquor. The addition of 2% - 4% wt. of the product to UF resin resulted in particleboard with significantly lower thickness swelling, an increase in MOR & IB strength, and lower formaldehyde emission.

Effectiveness of Nanocatalyst in the Improvement of Sorghum Bagasse Particleboard Bonded with Bio-Adhesive

Modification in the manufacturing process of bio-adhesive need to be carried out to improve the properties of sorghum bagasse particleboard, such as adding nanocatalyst into the bio-based adhesive. This study was conducted to determine the effectiveness of nanocatalyst in enhancing the properties of sorghum bagasse particleboard. Each nanocatalyst, such as zinc oxide (ZnO) and graphene oxide (GO), has been added to the citric acid and molasses-based adhesives. The target density of the particleboard was 0.8 g/cm3, with a board size of 350 mm × 350 mm × 6 mm. The particleboard was pressed using a hot-pressing machine at a temperature of 200°C and 10 MPa of pressure for 10 min. The physical and mechanical properties of the particleboard were evaluated, referring to JIS A 5908:2022 standard. The result showed that adding GO into the citric acid-based adhesive obtained a higher modulus of rupture (MOR) and lower thickness swelling (TS) than the others. Consequently, adding GO is more effective than adding ZnO into the bio-based adhesive in enhancing the properties of the particleboard. Keywords: bagasse sorghum, citric acid, molasses, Nanocatalyst GO, Nanocatalyst ZnO

Dolomit ve Olivin ile Kızılçam Odun Yonga Karışımından Üretilen Deneme Levhalarının Özellikleri. Bölüm 1. Fiziksel Özellikler

The effects of two mineral adducts (dolomite and olivine) as proportion in Calabrian pine wood chip based-experimental panels which bonded with synthetic adhesive (UF) were evaluated. It appears both minerals (P: calabrian pine wood chip-, X: Dolomite- Y: Olivine in composite proportions) improve the water repellent efficiency (WRE) properties at certain extent. In all experimental procedure, WRE increased with dolomite and olivine proportions higher than >10% in board formulations. The highest WRE of -34.2% and -35.4% were found with PX5 and PY5 samples that made with 1:1 (w/w) dolomite/wood and olivine/wood formulations, respectively. Like water sorption, similar trend was also found for thickness swelling (TS) properties. The lower TS values were found to be in range of -11.2 to -56.4% for dolomite-, and -55.5 to -69.5% for olivine based panels, respectively. Only samples of PX1, which produced 1:9 dolomite/wood chips (w,w, %) proportions, show higher IB value than control (PX0: 0.87 MPa vs PX1: 0.99 MPa) while rest of dolomite- pine wood panels show lower IB values. In contrast to dolomite, olivine appear to be improving effects on IB properties at certain conditions. The highest IB value of 1.21 MPa was found with sample PY4, which produced 4:6 olivine/wood chips (w,w, %) proportions, indicate approximately 39.1% higher IB value than control. It is notable that olivine seems to more effective than dolomite at similar board properation formulations in terms of lowering TS, WA and creating higher internal bond strength properties than dolomite based panels at similar experimental conditions. However, only sample of PY1, made with 1:9 (w, w,%) olivine/wood and proportions, show higher bending strength (13.27 MPa) and elasticity (2468.2 MPa than control (PY0:12.75 MPa vs 2245.2 MPa).

Innovative, low-cost eco-composite boards produced from high-energy milled wood, plastic waste, and bio-polymer

Currently, there is a big issue with waste, its processing and subsequent use. While there are many initiatives to replace materials that are poorly biodegradable, it is necessary to process and ideally use the waste that is already produced. In this study, the properties of composite boards made of waste materials and biodegradable polymer were investigated. The composite boards were made from wood and plastic waste using high-energy milling technology. This technology for material preparation is promising, as it includes controlling the morphology of particles, homogenizing the mixture, and drying the material during the milling process. The results showed higher flexural strength of high-density fiberboard (HDF) boards compared with tested composites with one exception. Wood/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [PHBV] composite exhibited 30% higher modulus of elasticity (MOE) than HDF due to the higher modulus of PHBV. The lowest thickness swelling (3%) and water absorption (12%) were measured for wood/recycled high density polythene (rHDPE) composite. The HDF boards recorded the lowest dimensional stability. The highest water absorption of tested composites was measured for wood/PHBV composite. The resistance to wood-rotting fungi was greatest for wood/PHBV composite containing marble powder, which corresponded to the results of scanning electron microscopy.

Characterization of plywood made from heat-treated rubberwood veneers bonded with melamine urea formaldehyde resin

The objective of the study is to evaluate the properties of the plywood made from rubberwood veneers thermally treated at various temperatures. Rotary-peeled rubberwood veneers were thermally treated at 160, 170, 180, and 190 °C under 1 bar pressure. 5-ply plywood panels were produced using melamine urea formaldehyde (MUF) resin as binder. Dimensional stability, i.e., water absorption (WA) and thickness swelling (TS) as well as mechanical properties of the plywood were assessed. The results demonstrated that the dimensional stability of the plywood made from thermally treated rubberwood veneers improved as indicated by lower WA and TS values. The reduction in WA and TS values increased along with treatment temperatures. Darkening in the plywood as a result of heat treatment was observed. Meanwhile, heat treatment at 170 °C and 180 °C resulted in plywood with the highest modulus of rupture (MOR), modulus of elasticity (MOE) and shear strength. However, beyond that temperature, the mechanical strength of the plywood started to decline. Based on the findings in this work it appears that heat treatment of rubberwood veneers at temperatures ranging from 160 to 180 °C could have a potential to improve overall properties of plywood panels.

Study on preparation of high-performance binderless board from Broussonetia papyrifera

Binderless particleboards were prepared without any resin adhesives from Broussonetia papyrifera trunk by hot pressing. The effects of particle size, pressing time, pressing temperature and board density on the physical and mechanical properties of binderless boards were investigated. The effects of chemical changes in Broussonetia papyrifera binderless particleboards on the board properties were investigated by chemical, spectroscopic and cellulose crystallinity analyses. The bonding performance of the latex of Broussonetia papyrifera was discussed. The results showed: (1) the smaller size of the particle, the higher internal bonding (IB) strength and lower thickness swelling (TS) of the binderless board had. The modulus of rupture (MOR), the modulus of elasticity (MOE) and the IB values of the boards increased with the increase of board density. Within a certain range, the binderless boards manufactured at higher temperature and longer pressing time had better properties. Under the optimum board manufacturing condition of 220 ℃/30 min/1.0 g/cm3, the Broussonetia papyrifera binderless board recorded a MOR 28 MPa, MOE 5.3 GPa, IB 2.74 MPa and 24 h TS of 7.4%, which met the performance requirements of Chinese national standard for heavy-duty particleboard. (2) The degradation of cellulose and hemicellulose during hot pressing resulted in decrease of cellulose and hemicellulose content and increase of extractives. Some of the degradation products form new bonding to increase the bonding strength and dimensional stability of the binderless boards. (3) The formation of pseudo-lignin and increased C–O–C and cellulose crystallinity of the boards during hot pressing contributed to high quality of the binderless boards. (4) The poplar veneers bonded with the latex of Broussonetia papyrifera had a certain bonding strength (0.6 MPa), indicating the latex played a positive role in self-bonding of the Broussonetia papyrifera particleboard.

High-performance wood scrimber prepared by a roller-pressing impregnation method

Wood scrimber is a wood-based composite material with high mechanical strength and large size, which can potentially replace the use of steel and cement in various fields. However, its poor dimensional stability and low flame retardancy limit its use in outdoor construction projects and fire-prone areas. To solve this, here we report a roller-pressing impregnation method to realize the deep penetration of resin using mechanical compression and low-pressure adsorption. Microstructural imaging by SEM and 3D ultra-deep field microscopy shows the phenol formaldehyde(PF) resin distribution of the roller-pressed wood scrimber (R-WS) is deeper and more uniform, which increases the flatness and crystallinity. The R-WS showed greatly improved dimensional stability, with 63 % and 35 % lower thickness swelling rate (TSR) and width swelling rate (WSR) compared with the traditional wood scrimber (T-WS). In terms of flame retardancy, the smoke production rate (SPR) and heat release rate (HRR) of R-WS decreased by 32.7 % and 52 %, respectively. The R-WS at 800 °C formed a dense char that content increased by 20 %, helping to inhibits combustion. The mechanical properties of R-WS were also improved, and the modulus of rupture (MOR), modulus of elasticity (MOE) and short-beam strength (SS) of R-WS increased by 31.2 %, 7.4 %and 26.7 %, respectively. The R-WS suffer toughness failure and wood-to-wood failure under bending and shear scenarios, respectively, indicating that the roller-pressing impregnation treatment enhanced toughness and bonding strength. In addition, the use of a rotating roller is expected to realize the continuous production of the dipping link, saving drying energy consumption and improving production efficiency. These properties are expected to promote the outdoor utilization and continuous production of wood scrimber.

Physical and mechanical properties of kenaf/flax hybrid composites

AbstractThis research investigates the physical and mechanical properties of hybrid composites made of epoxy reinforced by kenaf and flax natural fibers to investigate the hybridization influences of the composites. Pure and hybrid composites were fabricated using bi‐directional kenaf and flax fabrics at different stacking sequences utilizing the vacuum‐assisted resin infusion method. The pure and hybrid composites' physical properties, such as density, fiber volume fraction (FVF), water absorption capacity, and dimensional stability, were measured. The tests of tensile, flexural, interlaminar shear and fracture toughness (Mode II) were examined to determine the mechanical properties. The results revealed that density remained unchanged for the hybrid compared to pure kenaf/epoxy composites. The tensile, flexural, and interlaminar shear performance of flax/epoxy composite is improved by an increment of kenaf FVF in hybrid composites. The stacking sequence significantly affected the mechanical properties of hybrid composites. The highest tensile strength (59.8 MPa) was obtained for FK2 (alternative sequence of flax and kenaf fibers). However, FK3 (flax fiber located on the outer surfaces) had the highest interlaminar shear strength (12.5 MPa) and fracture toughness (3302.3 J/m2) among all tested hybrid composites. The highest water resistance was achieved for FK5 with the lowest thickness swelling.

Investigation of Physical, Mechanical Properties of Treated Date Palm Fibre and Kenaf Fibre Reinforced Epoxy Hybrid Composites

ABSTRACT This research is a comparative study of untreated and treated date palm fiber (DPF) and kenaf (KF)-reinforced epoxy hybrid composite and explores the properties of DPF. The prepared hybrid composites were characterized in terms of tensile properties, impact properties, physical behavior, water absorption, and thickness swelling. The composites were prepared by hand layup technique. Treated 30% date palm and 70% kenaf (T-3DP7K) showed the highest tensile strength (26.45 MPa) and modulus (4.54 GPa) among untreated and treated hybrid composites. The scanning electron microscope revealed the behavior of fiber and polymers and also the cause of tensile test failure. The impact strength of T-1DP1K revealed highest impact resistant (5493 J/m) among untreated and treated hybrid composites. Remarkably, alkali-treated hybrid composites reduced the water absorption and thickness swelling compared to the untreated composites. In untreated composites, higher DPF content composites showed higher moisture content and dimensional instability. Overall, we concluded that among all hybrid composites, T-3DP7K showed better tensile properties, lowest water absorption, and lowest thickness swelling, and T-7DP3K showed better impact properties.

Use of dry mixing-spraying process for the production of geopolymer-bonded wood and seagrass fibreboards

Mixing lignocellulosic fibres with a mineral binder to produce fibreboards is a challenging process due to their large volume per unit mass and their susceptibility to agglomeration (balling effect). The main objective in the dry mixing-spraying process presented in our study is the uniform distribution of the geopolymer binder in the lignocellulosic material. In this work, we compare the properties of two types of composites processed by implementing the abovementioned technique. Geopolymer-bonded fibreboards were produced using up to 50 wt% seagrass or wood fibres. Microscopy and X-ray micro-tomography investigations of the geopolymer composites indicated that their mechanical and physical properties depend on the size of incorporated fibres. Large seagrass fibres were appropriately mixed with the mineral binder matrix forming solid fibreboards that were able to reach the standard requirements for cement boards. More specifically, seagrass-based fibreboards exhibit up to 42% higher bending strength (up to 9.4 MPa) compared to fibreboards composed of wood fibres. In addition, their low thickness swelling and low mean heat release rate in a cone calorimeter (varying from 21.5 to 26.6 kW m−2) indicated a high resistance to water and fire. Considering the resulting properties of the produced fibreboards, the dry-mixing spraying process can be an appropriate technique for producing geopolymer composites containing large amounts of relatively long fibres.

Manufacturing and Characterization of Wide-Bundle Bamboo Scrimber: A Comparison with Other Engineered Bamboo Composites.

Controlling the variability in mat structure and properties in bamboo scrimber (BS) is key to producing the product for structural applications, and wide strip scrimber (WBS) is an effective approach. In this study, the effects of scrimmed bamboo bundle morphology and product density on the properties of WBS were investigated. WBS panels were manufactured and tested using wide (200 to 250 mm) bamboo strips with different fiberization intensity. Maximum strength properties (flexural, compressive, and shear strength), and lowest thickness swelling and water absorption were achieved with three or four passes due to the higher resin absorption by strips. For balanced product cost and performance, we recommend 1-2 fiberization passes and a panel density of 0.9-1.0 g/cm3. Panel mechanical properties were compared with other common bamboo composites. Bamboo scrimber products were highly variable in properties due to differing manufacturing processes, element treatments, and suboptimal mat structure. Products including laminated bamboo lumber and flattened bamboo made from nonfiberized elements show markedly different relationships between strength and elastic properties mostly due to inadequate bonding between the laminae, which causes premature bond-line failure. This study helped improve the understanding of the structure-property relationship of engineered bamboo products while providing insights into process optimization.

Preliminary study of particleboards manufactured with pine cones and Eucalyptus globulus capsules with a bio‐based polyurethane adhesive

AbstractThe following research aims to evaluate the feasibility of manufacturing particleboards based in Pinus radiata D. DON (PC) and Eucalyptus globulus (EC) capsules bonded with a natural oil polyurethane adhesive (PU). The particles of PC and EC were ground and dried. Particleboards were manufactured with PC and EC bonded with a natural oil‐based polyurethane adhesive (PC–PU and EC–PU). Boards composed of radiata pine wood and bio based polyurethane adhesive (RP–PU) and with radiata pine wood bonded with urea formaldehyde resin (RP–UF) were manufactured as reference samples. The physical and mechanical properties and formaldehyde emissions were evaluated according to international standards. The superficial morphology of the particleboards was studied through optical microscopy (OP) and scanning electron microscopy (SEM). The novel particleboards showed high resistance to moisture, low thickness swelling and a high internal bond strength, when compared with particleboards manufactured with the radiata pine wood particleboards bonded with PU and UF. Flexural properties in the new particleboards were slightly lower than the flexural properties of the reference samples RP–PU and RP–UF, since the distribution and geometry of the particles were different. The results of this research validate the use of P. radiata D. DON cones and E. globulus capsules, bonded with a bio‐based polyurethane adhesive, for the manufacture of novel particleboards. This research opens the possibility of an alternative use for the pine cones and Eucalyptus capsules as a new prime source for the manufacture of particleboards and other composite materials.

Eco-friendly bio-based adhesive for plywood from natural rubber latex (NRL)-blended isocyanate cross-linked starch.

Synthetic adhesives used in the production of plywood are a matter of concern because of the emission of carcinogenic gas formaldehyde, increased environmental pollution, and the depletion of fossil fuels. In this study, a bioadhesive composed of natural rubber latex (NRL) and rice starch was developed. However, rice starch has low moisture resistance, resulting in low adhesion. Thus, to enhance the effectiveness of NRL-blended rice starch-based bioadhesive, rice starch was cross-linked with polymeric 4,4″-diphenylmethane diisocyanate (pMDI) resin, which is an environment-friendly, formaldehyde free, and moisture resistant that is highly compatible with starch. The chemical interaction, viscosity, solid content, and gel time of the developed NRL-isocyanate cross-linked rice starch-based bioadhesive was investigated. The efficacy of the formulated bioadhesive was demonstrated by the fabrication of plywood. The presence of isocyanate and urethane capabilities in the bioadhesive formulations was confirmed by Fourier transform infrared spectroscopy (FTIR). The bioadhesive type Iso-A was discovered to have the highest viscosity of 8270mPa.s, whereas Iso-B has the shortest gel time of 3.46min and the highest solid content of 44%; the higher solid content accelerates the gel time. In terms of physical and mechanical properties of plywood, Iso-B has the lowest thickness swelling (TS) value of 13%, lowest water absorption (WA) value of 52% and shear strength value of 1.92MPa, which corresponds to the ISO 12466-2-2007 standard requirements. Based on the results, NRL-blended isocyanate starch-based bioadhesive could be a good potential raw material for eco-friendlyplywood industries with adequate accuracy.

Characteristic Properties of a Bamboo-Based Board Combined with Bamboo Veneers and Vacuum Heat-Treated Round Bamboo Sticks

In this study, a bamboo stick board with rotary-cut bamboo veneers was successfully fabricated. Additionally, vacuum heat (VH) treatment, which is a popular thermal modification method, was used to modify bamboo sticks. Therefore, the effects of different VH treatment temperatures on the dimensional stability and flexural properties of bamboo stick boards with and without bamboo veneers were investigated. For all boards, as the temperature increased to 220 °C, the thickness change rate and equilibrium moisture content decreased, and the flexural properties increased. The results exhibited that VH treatment improved the dimensional stability and flexural properties of the boards. Furthermore, the board with veneers had lower flexural properties and higher thickness swelling after water absorption than the board without veneers (BSB). The results indicated that bamboo veneer caused low flexural properties and high thickness swelling of the board compared to the BSB. However, the bamboo veneer played an aesthetic role in the appearance of the bamboo stick board.

Influence of wood leachate industrial waste as a novel catalyst for the synthesis of UF resins and MDF bonded with them

MDF (Medium Density Fiberboard) production processes produce a large amount of wood leachate as a hazardous waste. Wood leachate is a lignin-based waste material from the MDF production industry. It constitutes a potential environmental problem if discarded by penetrating into groundwater aquifers. Currently, there is no viable way for industrial MDF leachate waste to be transformed into environmentally friendly high value materials. The aim of this work was to present for the first time a novel approach which was successfully developed for the recovery of wood leachate industrial waste as a catalyst for the synthesis of UF adhesives for MDF panels. The leachates were examined by FTIR, 13 C NMR, and DSC as well as by evaluating the properties of fiberboards bonded with liquid UF resins. In addition, the other aim of this work was to capture the free formaldehyde gas emitted by MDF panels. It was of interest determine whether an MDF bonded panel prepared with a UF resin catalyzed by the wood leachate would exhibit lower formaldehyde emissions and the lowest thickness swelling, while still presenting a relatively good performance. The direct reuse of the fiberboard industrial leachate in the experiments demonstrated that the preparation method of the UF bonded fiberboard was environmentally friendly and sustainable. Therefore, this work arrived at some interesting conclusions that may be used as a base for future work on the recycling and reuse of MDF waste.