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Bio-Based Wood Adhesives: Current Advances in Polymer Architecture and Structure–Property–Sustainability Integration
(2026-07-01)
Dangwilailux, Panya
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Rachsiriwatcharabul, Natworapol
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Lakachaiworakun, Putipong
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Eakvanich, Visit
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Wattana, Wassachol
The development of bio-based adhesives has emerged as a viable strategy to reduce fossil-derived resin consumption in wood and wood-based panel applications. This review provides a polymer-focused assessment of adhesive systems derived from proteins, carbohydrates, lignin, and tannins, emphasizing molecular architecture, crosslinking chemistry, interfacial interactions, and structure–property relationships. Adhesive performance is primarily dictated by functional group density, crosslinking efficiency, and network topology. Protein-based adhesives rely on hydrogen bonding and covalent crosslinking with lignocellulosic substrates but require structural modification to improve hydrothermal stability. Carbohydrate-based systems, including starch and cellulose derivatives, offer reactive hydroxyl functionalities that enable oxidation, esterification, and etherification pathways for enhanced network formation. Lignin and tannins, characterized by phenolic and aromatic structures, facilitate condensation reactions and enable partial substitution of phenol in thermosetting resins, supporting low-formaldehyde or formaldehyde-free formulations. Hybrid polymer networks, particularly protein–carbohydrate and lignin-modified systems, demonstrate improved crosslink density, reduced hydrophilicity, and enhanced mechanical performance. Life cycle analyses indicate that increasing biogenic carbon content and minimizing fossil-based cross-linkers can lower global warming potential (GWP) and volatile organic compound (VOC) emissions. Overall, a structure–property–sustainability framework is proposed to guide molecular design and performance optimization of next-generation bio-based wood adhesives.
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Repurposing Senescent Oil Palm Trunks into Sustainable Plywood: A Green Alternative to Conventional Disposal Practices
(2026-01-01)
Rachsiriwatcharabul, Natworapol
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Dangwilailux, Panya
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Kalasee, Wachara
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Autthanit, Chaowat
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Lakachaiworakun, Putipong
This study evaluates the mechanical performance and carbon emission implications of producing plywood from senescent oil palm trunks (OPT), a readily available agricultural residue in Thailand. Veneers were dried using hot air at 90℃ and a hybrid hot air–microwave process before being fabricated into plywood with urea–formaldehyde adhesive. Mechanical tests showed that plywood from hybrid-dried veneers (OPP-H90-M2k) achieved higher tensile strength and modulus of rupture (MOR) than hot-air drying alone (OPP-H90), while bondline shear strength remained consistently high. However, MOR and modulus of elasticity values were lower than those of commercial plywood, suggesting that OPT plywood is currently better suited for non-structural interior applications such as furniture and partitions. A simplified carbon emissions inventory indicated that OPT plywood production released about 843 kg CO<inf>2</inf>-eq/m3, compared with 990 kg CO<inf>2</inf>-eq/m3 for open burning and 800– 1,200 kg CO<inf>2</inf>-eq/m3 for natural decomposition. Although its footprint is higher than advanced low-carbon plywood systems, the results suggest that OPT plywood offers a moderate emissions reduction and provides partial carbon storage within the product. Overall, converting OPT into plywood represents a practical alternative to unsustainable disposal practices and supports more sustainable biomass utilization in tropical agriculture.
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Effects of Wood Vinegar as a Coagulant in Rubber Sheet Production: A Sustainable Alternative to Acetic Acid and Formic Acid
(2025-07-01)
Eakvanich, Visit
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Lakachaiworakun, Putipong
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Rachsiriwatcharabul, Natworapol
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Wattana, Wassachol
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Kalasee, Wachara
Occupational exposure to commercial formic and acetic acids through dermal contact and inhalation during rubber sheet processing poses significant health risks to workers. Additionally, the use of these acids contributes to environmental pollution by contaminating water sources and soil. This study investigates the potential of three types of wood vinegar—derived from para-rubber wood, bamboo, and eucalyptus—obtained through biomass pyrolysis under anaerobic conditions, as sustainable alternatives to formic and acetic acids in the production of ribbed smoked sheets (RSSs). The organic constituents of each wood vinegar were characterized using gas chromatography and subsequently mixed with fresh natural latex to produce coagulated rubber sheets. The physical and chemical properties, equilibrium moisture content, and drying kinetics of the resulting sheets were then evaluated. The results indicated that wood vinegar derived from para-rubber wood contained a higher concentration of acetic acid compared to that obtained from bamboo and eucalyptus. As a result, rubber sheets coagulated with para-rubber wood and bamboo vinegars exhibited moisture sorption isotherms comparable to those of sheets coagulated with acetic acid, best described by the modified Henderson model. In contrast, sheets coagulated with eucalyptus-derived vinegar and formic acid followed the Oswin model. In terms of physical and chemical properties, extended drying times led to improved tensile strength in all samples. No statistically significant differences in tensile strength were observed between the experimental and reference samples. The concentration of acid was found to influence Mooney viscosity, the plasticity retention index (PRI), the thermogravimetric curve, and the overall coagulation process more significantly than the acid type. The drying kinetics of all five rubber sheet samples displayed similar trends, with the drying time decreasing in response to increases in drying temperature and airflow velocity.
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Thin-Layer Drying Model and Antifungal Properties of Rubber Sheets Produced with Wood Vinegar as a Substitute for Formic and Acetic Acids
(2025-05-01)
Wattana, Wassachol
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Lakachaiworakun, Putipong
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Rachsiriwatcharabul, Natworapol
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Eakvanich, Visit
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Dangwilailux, Panya
Currently, workers in the ribbed smoked sheet (RSS) rubber production industry face increasing health risks, primarily due to their direct involvement in converting fresh latex into raw rubber sheets. This process involves the manual addition of appropriately diluted commercial formic acid and acetic acid to induce coagulation, resulting in a tofu-like consistency, which is subsequently processed into rubber sheets. Previous studies have indicated that the use of commercial formic and acetic acids poses significant health hazards to workers and contributes to environmental pollution. Therefore, this study explores the feasibility of replacing commercial formic and acetic acids with wood vinegar derived from para-rubber wood, bamboo, and eucalyptus in the RSS production process. Wood vinegar samples from the three biomass sources were analyzed for their organic compound compositions using gas chromatography and subsequently used as coagulants in the preparation of raw rubber sheets. The drying kinetics and antifungal properties of the resulting sheets were then evaluated. The results revealed that wood vinegar derived from para-rubber wood contained the highest concentration of acetic acid (41.34%), followed by bamboo (38.19%) and eucalyptus (31.25%). Rubber sheets coagulated with wood vinegar from para-rubber wood and bamboo exhibited drying kinetics comparable to those obtained using acetic acid, with the two-term exponential model providing the best fit. Conversely, rubber sheets coagulated with eucalyptus-derived wood vinegar, which had a relatively high concentration of phenolic derivatives (22.08%), followed drying behavior consistent with the Midilli et al. model, similar to sheets treated with formic acid. In terms of antifungal properties, five fungal genera—Aspergillus, Penicillium, Fusarium, Trichoderma, and Paecilomyces—were identified on the rubber sheets. Fungal growth was most pronounced in the control samples (untreated with wood vinegar), whereas samples treated with wood vinegar exhibited significantly reduced fungal colonization. These findings indicate that wood vinegar is effective in inhibiting fungal growth on the surface of rubber sheets and may serve as a safer and more environmentally friendly alternative to commercial acid coagulants.
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Sound Absorption Properties of Natural Fiber Composite from Areca Nut Shells Fibers with Polyvinyl Alcohol
(2025-01-01)
Kalasee, Wachara
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Eakvanich, Visit
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Rachsiriwatcharabul, Natworapol
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Wattana, Wassachol
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Dangwilailux, Panya
This research investigates the development of sound-absorbing composites using areca nut shells fibers (ANS) bonded with polyvinyl alcohol glue, aiming to create an environmentally friendly and sustainable alternative to conventional synthetic materials. The research explores the effects of varying thicknesses (10, 20, and 30 mm) and fiber lengths (10, 20, and 30 mm) on the sound absorption performance of the composites. The sound absorption coefficient (SAC) was measured using the impedance tube method to determine the composites’ effectiveness across different frequency ranges. The results indicate that the thickness of the composite significantly enhances sound absorption, particularly in the low-frequency range (1,500–2,500 Hz). Composites with a fiber length of 30 mm demonstrated the most effective sound absorption properties at 0.90 above 1,600 Hz (ANS-T30-L30). Additionally, blending fibers of different lengths led to SAC changed behavior. This study contributes to the growing body of knowledge on sustainable materials by utilizing agricultural waste to produce functional and eco-friendly sound-absorbing composites.
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Mathematical Models of Natural Rubber Sheets Drying: Difference Acid Coagulation Cases
(2024-05-01)
Eakvanich, Visit
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Kalasee, Wachara
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Lakachaiworakun, Putipong
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Dangwilailux, Panya
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Wattana, Wassachol
The mathematical model for drying process is a useful tool in process optimization and drying chamber design. The research purposes of this study were to investigate the influence of drying temperature on drying time and the modelling the drying kinetics of the natural rubber (NR) sheets. The NR sheets which produce from commercial formic acid, commercial acetic acids, and ammonia plus commercial formic acid were studied at drying temperature of 40, 50, and 60°C and air speed of 0.5 m/s. The results indicated that the drying time was substantially reduced with an increase in temperature. The moisture content ratio of rubber sheets produce from commercial formic acid coagulation was similar to the sheets produce from commercial acetic acids coagulation. However, the drying time of them were longer than the drying time of the sheets produce from ammonia plus commercial formic acid coagulation. Finally, the logarithmic model was the best model which suitable to predict the moisture content ratio of the sheets drying with all experimental condition.
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Effect of Water Soluble Organic Carbon (WSOC) and Polycyclic Aromatic Hydrocarbons (PAHs) emitted by BioChar from the Rubber Sheets Processing Sewage Sludge Combustion
(2023-10-01)
Lakachaiworakun, Putipong
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Dangwilailux, Panya
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Eakvanich, Visit
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Kalasee, Wachara
The total particle mass concentration, size distribution, pH form, polycyclic aromatic hydrocarbons (PAHs) value, the concentration of total Benzo[a]pyrene Toxic Equivalence (BaPTE) and water-soluble organic carbon (WSOC) of smoke particles from the rubber sheets processing sewage sludge biochar burning were studied. In this work, the temperature was measured at 500 mm above the fire base by using K-type thermocouples and a continuously data logger. The result showed that the measured temperature value increased when decreasing the biochar moisture content. The highest average total smoke particle mass concentration values at the initial burning time was found to be 17.53 to 35.27 mg/m3 and then it was persistently reduced until the 60th minute, when the burning was stopped. The pH of biochar's smoke particles was higher than it was before combustion. The total smoke particle mass concentration, the mass median aerodynamic diameter (MMAD) and PAHs values decreased with increasing burning period and decreased the biochar moisture content. The largest BaPTE emission was observed at the highest moisture content, which was within the range of the greatest particle mass (less than 0.43 micron) in an initial combustion period. This value was about 60% that of a given the total value of BaPTE concentration. Meanwhile, the amount of PAHs, the BaPTE concentration and WSOC were depended on the smoke particle number, moisture content and combustion period.
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A Review of the Parameters Related to the Rubber Sheets Production: Major Constituents of Rubber Latex, Rubber Particles, Particle Interaction of Rubber Latex, Rubber Porous Structure, Rubber Drying Kinetics and Energy Consumption
(2023-01-01)
Eakvanich, Visit
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Kalasee, Wachara
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Dangwilailux, Panya
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Wattana, Wassachol
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Taweekun, Juntakan
Natural rubber (NR) is obtained principally from Para-rubber trees of the species Hevea brasiliensis which grow in tropical regions. Using ultra-centrifugation method, fresh latex (FL) from Para-rubber trees can be mainly divided into four fractions; an upper white layer consists of rubber particles, Frey-Wyssling particles in a yellow or an orange layer, C-serum phase and lutiods particles in the bottom fraction [1-3]. The averages of rubber particles have diameters of 0.02 to 3.0 micron, and they are protected by a complex film containing lipids and proteins [4-8]. The main forces of attraction between neighboring rubber particles in latex system can be divided into five force types; Structural Forces (SF), Van der Waals Interaction (VWI), Electrostatic Force (EF), Exclusion Interaction (EI) and Polymer-Polymer Interaction (PPI) [9]. The porous model of rubber structure used to describe moisture transfer was based on the existence of two different regions referred to as non-hygroscopic region and hygroscopic region. The rubber products drying always produced a considerable shrinkage effect which considered in the physical of the product, such as the diffusion coefficient, mass and heat transfer. An initial moisture content of raw material, the experimental temperature and the drying equipment had affect to the EMC isotherms and the drying kinetics. Finally, discussions on the implications of the results for strategies to reduce the energy consumption in RSS and STR20 block rubber are also presented.
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Sound Absorption Behavior Related to Reduce the Melamine-Urea-Formaldehyde (MUF) Adhesives for the Coffee Silver Skin Board Production
(2023-01-01)
Ekvanich, Visit
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Lakachaiworakun, Putipong
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Kalasee, Wachara
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Dangwilailux, Panya
The development of sound-absorbing panels which used coffee-silver-skin (CS) and melamine-urea-formaldehyde (MUF) as a composite board was studied. In this experiment, the objective was to examine the impact on the sound absorption coefficient (SAC) when incorporating wood husk into the composite board, specifically in the cases of CS (100%) and CS (90%) mixed with wood husk (10%), while simultaneously reducing the amount of MUF adhesive and adding corn starch (25%). It was observed that as the MUF content of the board decreased to 75%, the sound absorption coefficient average (SAA) were found to be 0.59 and 0.62 for the middle- and high-frequency ranges, respectively. For the frequency range higher than 3.15 kHz, the maximum SAC value of sample boards was 0.91 and the noise reduction coefficient (NRC) value was 0.47. While, the result showed the maximum SAC and the NRC value of sample boards were 0.93 and 0.48, respectively above the frequency range higher than 1.25 kHz for decreasing the MUF adhesive of board to 50%. Similarly, the addition of wood husk and corn starch mixed to CS could increase the SAA value of sample boards in the middle- and high-frequency range.
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Sound Absorption of Natural Fiber Composite from Sugarcane Bagasse and Coffee Silver Skin
(2023-01-01)
Kalasee, Wachara
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Lakachaiworakun, Putipong
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Eakvanich, Visit
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Dangwilailux, Panya
This study aimed to develop a sound-absorbing composite using sugarcane bagasse (SB) and coffee silver skin (CS) as raw materials. The composite boards were manufactured by bonding the fibers with Melamine Urea-Formaldehyde adhesive, ensuring a consistent thickness of 30 mm. Various densities were employed, namely 380, 450, and 520 kg/m3. The samples were fabricated with different fiber ratios, including SB100%, SB75% with CS25%, and SB50% with CS50%. The sound absorption coefficient (SAC) and noise reduction coefficient (NRC) were measured using the impedance tube method within a frequency range of 63–6,300 Hz. The experimental results revealed that the mixing ratio of CS exerted a notable influence on enhancing the SAC, while the density of the composite board exhibited a significant impact on increasing both the SAC and NRC. Among the densities tested, the optimal value was observed at 520 kg/m3, yielding a SAC value of 0.65 at a frequency of 1,000 Hz and an NRC value of 0.55 for the SB50-CS50 composite plate. These findings underscore the importance of considering the CS mixing ratio and composite board density when aiming to optimize sound absorption properties.

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