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RSM optimization of spray-coating parameters to enhance paper strength using cellulose nanocrystals extracted from young coconut husks
(2025-09-01)
Nuthongkum, Pilaipon
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Noonuruk, Russameeruk
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Bootchanont, Atipong
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Porjai, Porramain
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Wattanawikkam, Chakkaphan
This study optimizes spray-coating parameters for cellulose nanocrystals extracted from young coconut husks onto paper substrates using response surface methodology. CNCs were produced through acid hydrolysis and mechanical grinding, yielding nanocrystals with an average size of 116 nm and a crystallinity index increase from 28.89 % to 86.13 %. XRD and FTIR analyses confirmed high purity, while UV-vis revealed significant optical absorption in the UV range. Spray-coating parameters, including CNC concentration, volume, heating temperature, and heating duration, were optimized using a central composite design. The 2FI model revealed that CNC concentration and heating duration significantly affected film thickness, where higher CNC levels and longer heating durations produced thicker coatings. However, excessive CNC content led to agglomeration, compromising film quality. The quadratic model highlighted a significant relationship between coating parameters and tensile strength. Heat treatment notably enhanced mechanical properties, with optimal tensile strength reaching 26.15 ± 0.61 MPa-15 % higher than uncoated paper-under conditions of 4 % w/v CNC concentration, 1.5 ml volume, 75 °C heating temperature, and 35 min heating duration. This research highlights the potential of CNCs from young coconut husks as a sustainable reinforcement material, promoting agricultural waste valorization and enhancing paper properties.
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High-performance flexible thermoelectric generator based on silicone rubber and cover with graphite sheet
(2024-01-05)
Gobpant, Jakrit
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Klongratog, Bhanupol
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Rudradawong, Chalermpol
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Sakdanuphab, Rachsak
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Junlabhut, Prasopporn
Harvesting thermal energy through a flexible thermoelectric generator (FTEG) offers an excellent micro-power solution for energizing node sensors in the realm of Internet of Things (IoT) and wearable electronics. Nonetheless, current FTEG suffer from drawbacks including low efficiency, significant thermal resistance, and complex manufacturing procedures. In this study, a high-performance FTEG using silicone rubber was designed and fabricated using a straightforward process. The finite-element method was used to optimize the copper electrode thickness, and the bendable substrate layers with various thermal conductivity were studied for the first time. The copper electrode thickness of 0.1 mm was selected because it offers high flexibility and bendability while still providing a relatively high-power output. The 5 × 5 cm2 FTEG device was fabricated and covered with a bendable substrate. Silicon rubber (0.08 Wm−1K−1), silicon rubber added 5% graphene (0.14 Wm−1K−1), and graphite sheets (15 Wm−1K−1) were used as bendable substrates. The FTEG cover with graphite sheets has a maximum output voltage of 1.1 V under a temperature difference (ΔT) at 65 °C. Its maximum output power is 162.4 mW, corresponding to a power density of 6499.1 µW/cm2 under the same above ΔT. The experimental findings indicated that integrating a bendable substrate with high thermal conductivity and electrical insulation properties enhances the performance of the FTEG.
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Thickness Dependence of Thermoelectric Properties and Maximum Output Power of Single Planar Sb2Te3 Films
(2022-12-01)
Junlabhut, Prasopporn
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Nuthongkum, Pilaipon
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Harnwunggmoung, Adul
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Limsuwan, Pichet
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Hatayothai, Chanon
P-type Sb<inf>2</inf>Te<inf>3</inf> films with different thicknesses were deposited on polyimide substrates via heat treatment-assisted DC magnetron sputtering. The correlations between the thickness variance and the structure, dislocation density, surface morphology, thermoelectric properties and output power are investigated. As a result, it is clear that the film thickness and the heat treatment process during growth are related to the diffusion of deposited atoms on the substrate surface, leading to imperfection defects inside the films. The imperfections inside the films are affected by their properties. This work also presents the thermoelectric efficiency of a planar single leg of the deposited films with various thicknesses. The maximum power factor is 2.73 mW/mK2 obtained with a film thickness of 9.0 µm and an applied temperature of 100 °C. Planar Sb<inf>2</inf>Te<inf>3</inf> produced a maximum output power of 0.032 µW for a temperature difference of 58 K.
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Influence of Sputtering Power Density on the Thermoelectric and Mechanical Properties of Flexible Thermoelectric Antimony Telluride Films Deposited by DC Magnetron Sputtering
(2020-05-01)
Junlabhut, Prasopporn
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Nuthongkum, Pilaipon
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Sakdanuphab, Rachsak
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Harnwunggmoung, Adul
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Sakulkalavek, Aparporn
Antimony telluride (Sb<inf>2</inf>Te<inf>3</inf>) films were deposited on flexible polyimide substrates by DC magnetron sputtering technique using a 99.9% alloy Sb<inf>2</inf>Te<inf>3</inf> target. We measured structural, electrical, thermoelectric and mechanical properties with sputtering power density in the range 30–50 W. X-ray diffraction confirmed that all Sb<inf>2</inf>Te<inf>3</inf> films have high crystallinity with a significant preferential growth along the (015) plane. Surface morphologies were verified by scanning electron microscope: deposited film grain size increased with sputtering power density. The elemental composition was determined by energy dispersive x-ray spectroscopy. Electrical transport properties, carrier concentration, was measured by Hall effect measurement at room temperature. Electrical conductivity and Seebeck coefficient were simultaneously measured by a DC four-terminal method (ZEM-3). The power factor was strongly dominated by electrical conductivity, leading to a maximum of 1.95 mW/K2m with sputtering power 45 W at 300°C. The wettability test, based on the contact angle, evaluated surface energy and hydrophilicity. Nanoindentation was measured on a NHT2 CSM Instrument with diamond Berkovich indenter (B-P 31) at room temperature. The hardness and elastic modulus of deposited Sb<inf>2</inf>Te<inf>3</inf> films increased with the power density.
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Enhancing the thermoelectric properties of sputtered Sb2Te3 thick films via post-annealing treatment
(2020-04-15)
Junlabhut, Prasopporn
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Nuthongkum, Pilaipon
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Sakulkalavek, Aparporn
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Harnwunggmoung, Adul
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Limsuwan, Pichet
Sb<inf>2</inf>Te<inf>3</inf> films of more than 10 μm in thickness were deposited on flexible polyimide substrates by heat treatment-assisted DC magnetron sputtering. The post-annealing parameters including the temperature (150–350 °C) and time (15–60 min) were varied to investigate the microstructure, chemical composition, porosity and thermoelectric properties of the thick films. X-ray diffraction showed that both the as-deposited and post-annealed films were polycrystalline with significant preferential growth along the (015) plane. The films showed slightly off-stoichiometric compositions after post-annealing treatment. Increasing the annealing temperature and annealing time led to an increase in crystalline size and a decrease in porosity of the thick films. This was related to grain growth, agglomeration and surface improvement. The electrical transport and thermoelectric properties including carrier concentration, carrier mobility, electrical conductivity and Seebeck coefficient were investigated using Hall effect measurements and a ZEM-3 apparatus. A maximum power factor of 1.7 mW/K2m was obtained following annealing at 350 °C for 30 min.
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Effect of cobalt dopant on structural and optical properties of co-precipitated TiO2 nanopowders
(2016-01-01)
Junlabhut, Prasopporn
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Wattanawikkam, Chakkaphan
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Phoohinkong, Weerachon
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Mekprasart, Wanichaya
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Pecharapa, Wisanu
The effects of cobalt (Co) addition on structural and optical properties of TiO<inf>2</inf> nanopowders have been investigated. A co-precipitation method was employed to synthesize TiO<inf>2</inf> nanoparticles with various Co additives from 0-10 mol% using tetrabutyl titanate and Cobalt (II) nitrate hexahydrate as starting precursors for Ti and Co source, respectively. The crystallinity of Co-doped TiO<inf>2</inf> nanopowders is heightened by calcination process. The crystal structure, phase formation and the corresponding functional groups of Co-doped TiO2 were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The scanning electron microscope (SEM) was taken to observe their morphologies. The chemical compositions of Co additive into TiO<inf>2</inf> matrix are confirmed by EDAX. Their optical properties were investigated by diffuse reflectance spectroscopy. Diffuse reflectance spectra of samples exhibit the increasing absorption in visible region with an increasing Co content. The overall characterization results indicated that the crystallinity and optical properties of TiO<inf>2</inf> nanoparticles are significantly affected by Co dopant.
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Characterization of ZnO:Sn nanopowders synthesized by co-precipitation method
(2014-01-01)
Junlabhut, Prasopporn
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Mekprasart, Wanichaya
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Noonuruk, Russameeruk
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Chongsri, Krisana
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Pecharapa, Wisanu
ZnO:Sn nanopowders were synthesized by co-precipitation method using zinc acetate dihydrate and tin (IV) chloride hexahydrate as a precursors. Co-precipitate of ZnO:Sn nanopowders with various Sn additive 0-50 %wt were obtained by calcination process at 500 °C. The corresponding functional groups and chemical bonding of the samples were investigated by Fourier Transform Infrared Spectroscopy (FTIR). The effects of Sn addition on structural and morphological properties of ZnO:Sn nanopowders have been investigated by X-ray diffraction (XRD), Raman Spectroscopy (Raman) and Scanning electron microscopy (SEM). The chemical bonding of Zn-O, Sn-O and Sn-OH in ZnO:Sn nanopowders were observed by FTIR results. The phase formation of this coumpound was observed with increasing Sn content with calcined at 500 °C. These results indicate that the crystallinity and structural of ZnO nanopowders are significantly affected by Sn dopant.
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Optical absorptivity enhancement of SiO2 thin film by Ti and Ag additive
(2013-01-01)
Junlabhut, Prasopporn
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Boonruang, Sakoolkarn
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Pecharapa, Wisanu
This paper presents the visible optical absorptivity enhancement of SiO<inf>2</inf> thin films by Ti and Ag additive. SiO<inf>2</inf> thin films were prepared on glass substrate by sol-gel technique. Methacryloxy propyl trimethoxysilane (MAPTMS), Titanium isopropoxide (TiP) and Silver nitrate were used as precursors. MAPTMS was dissolved in absolute ethanol with various Ti and Ag content. The physical properties of as-prepared films were characterized by X-ray diffraction (XRD) and Transmission electron micrograph (TEM). The effects of Ti and Ag addition on optical properties were investigated from its optical absorption measured by UV-VIS Spectrophotometer (UV-VIS). XRD patterns shows the formation of TiO<inf>2</inf> and Ag in thin film. The effect of Ti and Ag additive on SiO<inf>2</inf> thin films were scrutinized by mean of the optical absorption in visible region. XRD and TEM results disclose the existence of TiO<inf>2</inf> and Ag nanoparticles in the as-prepared films. It can be observed that the improvement in optical absorption in both UV and visible region can be efficiently accomplished by the incorporation of Ti and Ag into SiO<inf>2</inf> films. © 2013 The Authors.
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Fabrication of holographic lens as a coupling device in surface plasmon resonance biosensor
(2010-06-25)
Junlabhut, Prasopporn
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Phoojaruenchanachai, Suwannee
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Pecharapa, Wisanu
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Boonruang, Sakoolkan
Holographic lens is proposed as a light coupling device integrated in surface plasmon resonance (SPR) biosensor chips to concise the SPR optical system. Having a sub-wavelength pattern with an asymmetric profile, the lens couples light via a first order wave which excites the surface plasmon wave along the sensing spot. The design and fabrication process are included in this work, where a laser interference lithography technique is utilized as it requires only single step to write a lens' pattern. The preliminary result indicates the first order wave with 20% diffraction efficiency. © 2010 Copyright SPIE - The International Society for Optical Engineering.

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