Coconut Fibre and Sawdust as Green Building Materials: A Laboratory Assessment on Physical and Mechanical Properties of Particleboards

This paper evaluates, via a laboratory assessment, the physical properties (BS EN 323:1993, BS EN 324) and mechanical performance (BS EN 310: 1993) of hybrid particleboards using agricultural wastes, namely coconut fibre and sawdust. The process begins with the preparation of the materials where they are sieved and retained with the 5-mm sieve and then oven-dried. The hybrid particleboard mixed with the addition of resin (urea formaldehyde) was sprayed and hot pressed. The hot press temperature was set at 180 °C, with the resin content of 8 wt.% and the design density of 650 kg/m3 used in producing the particleboard. The percentage/ratio of the composition of sawdust (SD) to coconut fibre (CF) varied ranging from 100SD:0CF to 70SD:30CF, 50SD:50CF, 30SD:70CF, and 0SD:100CF. Meanwhile, as for the thickness of the boards, it was categorised into three groups which are 16 mm, 20 mm, and 32 mm. The particleboards were conditioned to the room temperature for seven days before being tested for physical properties and mechanical performances. The results show that the most optimum composition of sawdust to coconut fibre is 0% sawdust to 100% coconut fibre (0SD: 100CF) and the optimum thickness is 20 mm, where its density is 761.99 kg/m3, swelling thickness is 11.98%, and water absorption at 37.64%. With the modulus of elasticity of 1510 N/mm2, the modulus of rupture of 17.8 N/mm2, and the internal bonding of 1.08 N/mm2, they satisfied the universal standard of Particleboard Type P3 of BS EN 312:2010.

Mechanical Performance and Dimensional Stability of Bamboo Fiber-Based Composite

The bamboo fiber-based composite (BFBC) has high-performce in terms of mechanical properties and dimensional stability. In this study, BFBCs were prepared with different hot-pressing temperatures (150 °C, 160 °C, 170 °C, 180 °C, 190 °C, and 200 °C) and designed with different densities (1.05 g/cm3, 1.10 g/cm3, 1.15 g/cm3 and 1.20 g/cm3), and their selected properties were evaluated. Temperature affected BFBC performance, which, with a general increase in temperature, showed a decrement in mechanical properties and an improvement in dimensional stability. Holocellulose content significantly decreased, and the color of BFBC became darker with the increasing of the press temperature. As the density of BFBC increased, the modulus of elasticity (MOE) significantly increased from 23.09 GPa to 27.01 GPa with the increase in temperature. The thickness swelling ratio (TSR), width swelling ratio (WSR) and water absorption ratio (WAR) declined by more than 30% with the increase in density. Overall, the results of this study provide a theoretical basis and a source of technical support to promote the design, application, and popularization of BFBC in different fields.

Optimization of hot-press parameters for plywood with environmental aluminophosphate adhesive

An aluminophosphate adhesive was used as the binder in plywood. The hot-pressing parameters of aluminophosphate adhesive-based plywood (APPs) including hot-press temperature (A), time (B), and pressure (C) were optimized using response surface methodology. Results indicated that the hot-press temperature was the most dominant factor. The maximum bonding strength of 1.98 MPa was found with an optimal parameter of 171 °C (hot-press temperature), 7.5 min (hot-press time), and 1.0 MPa (hot-press pressure). Additionally, the chemical reaction mechanism between aluminophosphate adhesive and wood fibers was characterized by X-ray photoelectron spectroscopy (XPS). Results showed that good interaction was generated between wood fibers and adhesives through their surface functional groups. In conclusion, the optimized pressing conditions of plywood significantly improved bonding strength of APPs.

Optimization of processing parameters for the manufacturing of jute stick binderless particleboard

This study investigated the effects of processing parameters, namely particle mixing ratios, press temperatures, and time for the manufacturing of jute stick binderless particleboard (JBPB). Different ratios of fine and coarse particles, press temperature (160 to 240 °C) and press time (4 to 10 min) were used for JBPB fabrication with a target density of 0.9 g/cm3. The dimensional stability and mechanical properties of JBPB were determined according to Japanese Industrial Standard JIS A 5908 (2003). The result shows that the most favorable pressing conditions in the manufacturing process were press temperature of 220 °C for 6 min with a mixing ratio of 50:50 (fine: coarse). The modulus of rupture (MOR), modulus of elasticity (MOE), and internal bonding (IB) of JBPB was 16.35 N/mm2, 3872.99 N/mm2, and 1.07 N/mm2, respectively, which met the minimum requirement for type-18 of particleboard JIS A 5908 (2003) except for the value of MOR. The bonding mechanism was analyzed by the chemical changes in the raw materials after the fabrication of JBPBs. The pentosans present in the raw material decreased with the increased press temperatures. In this study, the hemicellulose was decomposed which may accelerate the self-bonding of the JBPB at high temperatures. The thermal gravimetric analysis (TGA) revealed that the JBPB showed good thermal stability with the increase of press temperatures. Fourier transform infrared (FTIR) spectra indicated that the removal of hydroxyl groups which increased the dimensional stability of JBPBs. Hence, it could be concluded that by controlling particle mixing ratio (50:50) at high press temperature with proper press time, high-performance jute stick binderless particleboard could be successfully developed which has a variety of applications.

Development of Wood Composites from Recycled Fibres Bonded with Magnesium Lignosulfonate

The potential of producing ecofriendly composites from industrial waste fibres, bonded with magnesium lignosulfonate, a lignin-based formaldehyde-free adhesive, was investigated in this work. Composites were produced in the laboratory using the following parameters: a hot press temperature of 210 °C, a pressing time of 16 min, and a 15% gluing content of magnesium lignosulfonate (on the dry fibres). The physical and mechanical properties of the produced composites were evaluated and compared with the European Standard (EN) required properties (EN 312, EN 622-5) of common wood-based panels, such as particleboards for internal use in dry conditions (type P2), load-bearing particleboards for use in humid conditions (type P5), heavy-duty load-bearing particleboards for use in humid conditions (type P7), and medium-density fibreboards (MDF) for use in dry conditions. In general, the new produced composites exhibited satisfactory mechanical properties: a bending strength (MOR) (18.5 N·mm−2) that was 42% higher than that required for type P2 particleboards (13 N·mm−2) and 16% higher than that required for type P5 particleboards (16 N·mm−2). Additionally, the modulus of elasticity (MOE) of composites (2225 N·mm−2) was 24% higher than that required for type P2 particleboards (1800 N·mm−2) and equivalent to the required MOE of MDF panels for use in dry conditions (2200 N·mm−2). However, these ecofriendly composites showed deteriorated moisture properties, i.e., 24 h swelling and 24 h water absorption, which were a distinct disadvantage. This should be further investigated, as modifications in the lignosulfonate formula used and/or production parameters are necessary.

Investigation of a formaldehyde-free cottonseed flour-based adhesive for interior plywood

A new formaldehyde-free wood adhesive, primarily composed of defatted cottonseed flour (CF) and polyamine-epichlorohydrin (K736) resin, was investigated for the preparation of interior plywood. Sodium hydroxide was an essential component of the adhesive. The effects of pH values of the CF-K736 adhesive, the CF/K736 weight ratio on the pot life of the adhesive, and the water resistance of the resulting plywood panels were investigated in detail. The hot-pressing temperature and time were optimized in terms of the water resistance of the resulting plywood panels. The resulting 5-ply plywood panels met the industrial water resistance requirements for interior application under the following conditions: pH > 11, CF/K736 weight ratio in the range of 8/1 to 5/1, hot-press temperature ≥ 120 °C, and hot-pressing time > 4 min. The pot life of the adhesive was approximately 3 h when the pH was 12 and the CF/K736 weight ratio was 8/1. The curing mechanism of the adhesive is discussed.

Investigation on the microstructural characteristics and quasi-static puncture resistance of both domesticated and wild silkworm cocoons

The very thin and lightweight silkworm cocoon has outstanding mechanical properties attributed to its specific composite microstructure. However, the microstructures of the cocoons have not been studied quantitatively, and their anti-puncture performance has not been examined as well. In this study, both domesticated ( Bombyx mori) and wild silkworm cocoons ( Antheraea pernyi, Antheraea mylitta and Samia canningi) were investigated for their microstructures using fractal theory, and their quasi-static puncture resistance was tested and compared. In addition, the effects of cocoon layers and hot-press treatments on the puncture resistance of two cocoon types ( B. mori and A. pernyi) were investigated. The three wild cocoons demonstrated significantly higher fractal dimensions, higher fiber intersectional densities and low porosities, indicating their structures are more optimized. They also displayed better puncture resistance than B. mori. Increased layer numbers could significantly increase the puncture resistance of both cocoon types and A. pernyi showed more remarkable increases. Moreover, the two cocoon types showed optimum puncture resistance after heat treatment with hot-press temperature of 135℃ and pressure of 25 MPa, and A. pernyi showed better puncture resistance after such treatment. Finally, both the maximum puncture force and puncture energy of cocoons displayed a linear increase with the increasing fractal dimensions. The new insights can guide the development of novel protective fiber composites with desirable and predictable anti-puncture performance.

Characteristics of Bamboo Particleboard Bonded with Citric Acid-Starch Using Three-Step Press Cycle Method

In an attempt to reduce the use of a formaldehyde-based adhesive that is dangerous for both human health and environment, several studies had been done to develop particleboard with natural bio-based adhesives. Between those bio-based adhesives that have been investigated, the combination of citric acid-starch was potential to be developed further as an adhesive to particleboard. In this research, the effect of starch addition and press temperature on the properties of bamboo particleboard were evaluated. This research uses a combination of citric acid/starch with the composition weight ratio of 100/0, 90/10, 80/20 and 70/30 and press temperature of 160, 180 and 200 °C. The manufacture of particleboard also used a three-step press cycle method which has not been done before in Petung bamboo particleboard production. The result showed that the three-press cycle method used in this research was able to produce a board with excellent properties than board produced by single-step press cycle method. This showed that the manufacture of the board in this research was more efficient to produce citric acid-starch bonded particleboard than previous method being used. The results also showed that both the addition of starch and the increase of press temperature especially improved bamboo particleboard mechanical properties. The board with the optimum properties resulted from particleboard with citric acid/starch adhesive with the composition weight ratio of 80/20 and press temperature of 180 °C which could meet JIS A 5908 (2003) type 18 requirement.