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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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    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/m<sup>3</sup>, compared with 990 kg CO<inf>2</inf>-eq/m<sup>3</sup> for open burning and 800– 1,200 kg CO<inf>2</inf>-eq/m<sup>3</sup> 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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    Mathematical Models of Natural Rubber Sheets Drying: Difference Acid Coagulation Cases
    (2024-05-01) ; ;
    Lakachaiworakun, Putipong
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    Dangwilailux, Panya
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    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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    A review of air pollution and solutions way management related to ribbed smoked sheets (RSS) production of community-level rubber cooperatives in thailand: Smoke, soot and PAHs particles
    (2020-06-01) ;
    Teekapakvisit, C.
    In Thailand, RSS chamber of community-level rubber cooperatives can be classified into two models: old and new model, named after the years of their establishment. Hot gas as a heat supply from Para-rubber (PR) wood (Hevea brasiliensis) combustion is used for removing moisture from the natural rubber (NR) sheets. Smoke and soot particles from PR wood burning has effected to the quality of the NR sheet and the pollution in the workplace area and lead to health problems of the worker. Cascade impactors are equipment for measuring the smoke and soot particles size distribution from PR wood combustion. PAHs compounds from PR wood combustion were found 15 different PAHs components (Tekasakul et al., 2005; Furuuchi et al., 2006). Important methods in decreasing smoke and soot particles from combustion of PR wood for rubber smoking chamber are separation equipment and ventilation designed by computational fluid dynamics (CFD) technique. In this article, the separation method is focused on smoke and soot particle collection to maintain the quality of the NR sheet. This equipment is reviewed both indoor and outdoor, for example, an impaction wall, electrostatic precipitator, stainless-wire, etc. This review indicates that the ESP installing between the furnace and the smoking chamber is suitable to eliminate aerosol particles at the rubber smoking industry. In addition, CFD technique reports is aimed at collecting aerosol particles for decreasing smoke and soot particles emission from rubber smoking chamber is presented.
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    Sound Absorption of Natural Fiber Composite from Sugarcane Bagasse and Coffee Silver Skin
    (2023-01-01) ;
    Lakachaiworakun, Putipong
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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/m<sup>3</sup>. 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/m<sup>3</sup>, 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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    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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    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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    Effect of wood vinegar substitutes on acetic acid for coagulating natural para rubber sheets during the drying process
    (2021-09-01) ;
    Dangwilailux, Panya
    The coagulating properties of wood vinegar from para rubber wood, bamboo, and coconut shell used as a substitute for acetic acid in the production process of natural rubber (NR) sheets were investigated and considered. For the dirt and volatile content, the tensile strength at break, the percentage of elongation at break, and the 300% modulus, the results showed that the types of wood vinegar coagulants were not significantly different from acetic acid. However, the Mooney viscosity and plasticity retention index (PRI) properties were significantly different from those of acetic acid. The NR sheet temperature increased rapidly during the first hour after the drying process started due to heat transfer from the hot air. Afterward, the temperature of the NR sheet samples began to stabilize. When the drying process started, the drying temperature was increased, so the trend was reducing the drying time. For the yellowness index (YI) value, the increase in the YI value was related to the type of coagulating material, the increase in the airspeed, and the drying temperature. The dried sheet samples using para rubber wood vinegar as the coagulating material had a color value at the same level as acetic acid and the referent. However, the bamboo and coconut shell wood vinegars were at a lower level. In comparing the YI value data between the experimental results and prediction values, the second-degree model had a better fit in prediction than the zero-degree and first-degree models. This result was confirmed by the higher mean of the coefficient of determination. The dried sheet product coagulated by using wood vinegar had fungus growth prior to supplying it to the customer.
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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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    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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    Improvement soot particles separation equipments for rubber smoking chamber
    (2009-12-01)
    Soot produced from rubber tree wood combustion during the process of drying natural rubber sheets has been shown to produce negative health effects for workers, as well as poorer quality rubber sheets. This study examined ways to improve soot particle separation equipment for rubber smoking chambers. An impaction wall was able to catch all soot particles ranging in size from 3.3-4.7 microns and a modified electrostatic precipitator, installed outside of the rubber smoking chamber in order to decrease danger to workers and with the highest available voltage supply of 12 kV, captured soot particles 0.43-3.3 microns in size. This modified precipitator operated longer than the usual time 120 hours or more before requiring cleaning; equivalent to smoking about 12 lots of rubber sheets or operating for 3 months during high rubber production season. The total efficiency of soot particle separation through the use of the modified collection equipment was more than 50% for all tests. In addition, the color index of rubber sheets used in the testing improved from 6.0 to 12.0. Coloration, which is a measure of quality, was better than sheets from smoking chamber lacking soot particle separation equipment. Copyright © Taiwan Association for Aerosol Research.
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    Prediction of size distribution and mass concentration of smoke particles on moisture content and combustion period from para rubber wood burning
    (2021-06-02) ;
    Dangwilailux, Panya
    The size distribution and total particle mass concentration (TPMC) of smoke particles from para rubber wood (Hevea brasiliensis) combustion in the ribbed smoked sheet (RSS) process were studied. In this experiment, temperature data values of para rubber wood combustion were recorded at 500 mm above the base of the fire by K-type thermocouples. The wood moisture content and wood combustion period were used to find and improve an equation of smoke particle size distribution (SPSD) and TPMC by the response surface method (RSM). An eight-stage Andersen air sampler and a high-volume sampler were used to measure and calculate SPSD and TPMC, respectively. Resulting data in this experiment showed that TPMC ranged from 3.12 to 77.42 mg/m<sup>3</sup> . SPSD was single mode in which MMAD, mass median aerodynamic diameter, ranged from 0.64 to 1.27 microns for para wood with moisture content ranging from 31.5 to 89.7% dry weight basis. The combustion period and moisture content of para wood have a direct effect on the change of temperature data above the base of the fire and the TPMC and MMAD values. For predicting TPMC and MMAD values by the para wood moisture contents in each combustion period, the results found that the second-degree model was a better plot than the first-degree model, confirmed by higher values of the coefficient of determination (R<sup>2</sup> ).
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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) ;
    Lakachaiworakun, Putipong
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    Rachsiriwatcharabul, Natworapol
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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.