ABSTRACT
The surface roughness and wettability of wood are critical aspects to consider when producing laminated wood products with adhesive applications. This study aims to investigate the surface roughness and dynamic wettability of Jabon wood in the presence of melamine formaldehyde (MF)-based adhesives. Commercial MF adhesives (MF-0) and modified MF adhesives (MF-1) were applied to Jabon wood, which includes tangential (T), radial (R), and semi-radial (T/R) surfaces. The surface roughness of Jabon wood was assessed using a portable stylus-type profilometer. The low-bond axisymmetric drop shape analysis (LB-ADSA) method was employed to identify the contact angle (θ) of the MF-based adhesives on Jabon wood. The wettability was determined by evaluating the constant contact angle change rate (K value) using the Shi and Gardner (S/G) model. Dynamic mechanical analysis (DMA) was employed to investigate the viscoelastic characteristics of the interphase analysis of the wood and MF-based adhesives. The roughness level (Ra) of the Jabon board ranged from 5.62 to 6.94 µm, with the T/R having a higher level of roughness than the R and T. MF-0 exhibited a higher K value (0.262-0.331) than MF-1 (0.136-0.212), indicating that MF-0 wets the surface of Jabon wood more easily than MF-1. The wood-MF-0 interphase reached a maximum stiffness of 957 N/m at 123.0 °C, while the wood-MF-1 had a maximum stiffness of 2734 N/m at 110.5 °C. In addition, the wood-MF-0 had a maximum storage modulus of 12,650 MPa at a temperature of 128.9 °C, while the wood-MF-1 had a maximum storage modulus of 22,950 MPa at 113.5 °C.
ABSTRACT
Cross-laminated timber (CLT) has become a popular engineered wood product due to its innovative properties and rapid development, which involves the use of various wood species and adhesives. This study aimed to assess the effect of glue application on the bonding strength, delamination, and wood failure of CLT made from jabon wood and bonded with a cold-setting melamine-based adhesive at three different rates: 250, 280, and 300 g/m2. The adhesive was composed of melamine-formaldehyde (MF) by adding 5% citric acid, 3% polymeric 4,4-methylene diphenyl diisocyanate (pMDI), and 10% wheat flour. Adding these ingredients increased the adhesive viscosity and decreased the gelation time. The CLT samples, made using cold pressing in the melamine-based adhesive at a pressure of 1.0 MPa for 2 h, were evaluated as per the standard EN 16531:2021. The results revealed that a higher glue spread resulted in a greater bonding strength, lower delamination, and a higher wood failure. The glue spread was shown to have a more significant influence on wood failure compared with delamination and the bonding strength. The application of 300 g/m2 glue spread (MF-1) on the jabon CLT led to a product that met the standard requirements. The use of modified MF in cold-setting adhesive produced a potential product that could be a feasible option for future CLT production in terms of its lower heat energy consumption.
ABSTRACT
The use of natural fibers or particles as alternative raw materials for particleboard production is essential due to the shrinking forest area. Currently, dung waste from the Sumatran elephant (Elephas maximus sumatranus) is being used as a raw material for particleboard due to its high fiber content. Although the product still has inferior mechanical and physical characteristics, it can be improved by layering bamboo. Therefore, this study aimed to enhance the mechanical and physical qualities of elephant dung particleboard by adding layers of bamboo. The particleboard constructed had three layers; namely, the face and back in the form of a bamboo layers, as well as the core, which was in the form of elephant dung. The elephant dung was evenly mixed with isocyanate adhesive using a spray gun, and the bamboo layers were coated with adhesive on one side of the surface. The sample was subjected to a hot press at a temperature of 150 °C and 30 kg/cm2 pressure for 10 min. Generally, JIS A 5908-2003 is the specification used to test the physical and mechanical properties of particleboard. During the experiment, the characteristics examined include density, moisture content, water absorption, thickness swelling, modulus of elasticity, modulus of rupture, and internal bonding, which were enhanced by using layers of bamboo. The results showed that the physical properties of the particleboard with bamboo layers were a density of 0.62-0.69 g/cm3, a moisture content of 7.87-10.35%, water absorption of 38.27-68.58%, and a thickness swelling of 10.87-30.00%, which met the minimum standards of JIS A 5908-2003. The mechanical characteristics had values for the modulus of elasticity of 1952-7282 MPa, the modulus of rupture of 20.44-68.27 MPa, and the internal bonding of 0.16-0.38 MPa, which met the JIS A 5908-2003 standard. Based on these results, the particleboard with Belangke bamboo layers was the best in this study.
ABSTRACT
Asian countries have abundant resources of natural fibers, but unfortunately, they have not been optimally utilized. The facts showed that from 2014 to 2020, there was a shortfall in meeting national demand of over USD 2.75 million per year. Therefore, in order to develop the utilization and improve the economic potential as well as the sustainability of natural fibers, a comprehensive review is required. The study aimed to demonstrate the availability, technological processing, and socio-economical aspects of natural fibers. Although many studies have been conducted on this material, it is necessary to revisit their potential from those perspectives to maximize their use. The renewability and biodegradability of natural fiber are part of the fascinating properties that lead to their prospective use in automotive, aerospace industries, structural and building constructions, bio packaging, textiles, biomedical applications, and military vehicles. To increase the range of applications, relevant technologies in conjunction with social approaches are very important. Hence, in the future, the utilization can be expanded in many fields by considering the basic characteristics and appropriate technologies of the natural fibers. Selecting the most prospective natural fiber for creating national products can be assisted by providing an integrated management system from a digitalized information on potential and related technological approaches. To make it happens, collaborations between stakeholders from the national R&D agency, the government as policy maker, and academic institutions to develop national bioproducts based on domestic innovation in order to move the circular economy forward are essential.
