| Practical approach in surface modification of biaxially oriented polypropylene films for gravure printability | |
| Nuntapichedkul B., Tantayanon S., Laohhasurayotin K. | |
|
|
|
| Abstract | |
| Biaxially oriented polypropylene (BOPP) film is one of the most popularly used materials for the gravure printing process in flexible packaging industry. The skin layers of BOPP film were associated with 3-6 weight % of propylene-ethylene copolymer. These films were completely biaxial-oriented by sequential stretching process after which the film surfaces were subjected to corona treatment integrated in the production line. The FT-IR results exhibited that polar functional groups as carbonyl molecules were established on the corona-treated BOPP film. The contact angles of these BOPP films were measured; the surface free energies (SFE) were then calculated. AFM topographical images also agreed well with the SFE which increased as the contents of propylene-ethylene copolymer increased. An approximated 20% increased SFE was obtained for the BOPP film that was associated with 6% propylene-ethylene copolymer. The printing quality on BOPP films was tested by light microscope which confirmed that the chromatic resolution of the printed images improved down to even more smaller groove sizes, 10 or 5 dot%. This improvement was also examined and found to correspond well with the interfacial tensions and work of adhesion between the inks and the modified BOPP films. © 2014 Elsevier B.V. | |
| keywords | |
| Ethylene; Free energy; Graphic methods; Image enhancement; Ink; Packaging materials; Plastic films; Propylene; Surface treatment; Biaxially oriented polypropylene film; BOPP; Corona treatment; Ethylene copolymer; Flexible packaging industry; Polar functional groups; Surface free energy; Topographical images; Polypropylenes | |
|
|
|
| more information
_______________________________________________________________ |
| Production of fatty acid methyl esters over a limestone-derived heterogeneous catalyst in a fixed-bed reactor | |
| Ketcong A., Meechan W., Naree T., Seneevong I., Winitsorn A., Butnark S., Ngamcharussrivichai C. | |
|
|
|
| Abstract | |
| Production of fatty acid methyl esters (FAME) via the transesterification of different vegetable oils and methanol with a limestone-derived heterogeneous catalyst was investigated in a fixed-bed reactor at 65 °C and ambient pressure. This heterogeneous catalyst, as a 1 or 2. mm cross-sectional diameter extrudate, was prepared via a wet mixing of thermally treated limestone with Mg and Al compounds as binders and with or without hydroxyethyl cellulose (HEC) as a plasticizer, followed by calcination at 800 °C. The physicochemical properties of the prepared catalysts were characterized by various techniques. Palm kernel oil, palm oil, palm olein oil and waste cooking oil could be used as the feedstocks but the FFA and water content must be limited. The extrudate catalyst prepared with the HEC addition exhibited an enhanced formation of FAME due to an increased porosity and basicity of the catalyst. The FAME yield was increased with the methanol/oil molar ratio. The effect of addition of methyl esters as co-solvents on the FAME production was investigated. The structural and compositional change of the catalysts spent in different reaction conditions indicated that deactivation was mainly due to a deposition of glycerol and FFA (if present). The FAME yield of 94.1. wt.% was stably achieved over 1500. min by using the present fixed-bed system. © 2013 The Korean Society of Industrial and Engineering Chemistry. | |
| keywords | |
| Biodiesel; Catalyst deactivation; Chemical reactors; Esterification; Esters; Fatty acids; Limestone; Palm oil; Transesterification; Compositional changes; Effect of addition; Fatty acid methyl ester; Fixed-bed reactors; Heterogeneous catalyst; Hydroxyethyl celluloses (HEC); Physicochemical property; Reaction conditions; Oils and fats | |
|
|
|
| more information
_______________________________________________________________ |
| In situ generated silica in natural rubber latex via the sol-gel technique and properties of the silica rubber composites | |
| Poompradub S., Thirakulrati M., Prasassarakich P. | |
|
|
|
| Abstract | |
| Natural rubber (NR) composites reinforced by silica generated in situ within the NR matrix were prepared by the sol-gel process using tetraethoxysilane (TEOS) as the silica precursor. The effect of the TEOS content, water: TEOS mole ratio, reaction time and temperature on the in situ silica content formed in the NR latex were investigated. The results indicated that the suitable condition to produce a high silica content (54 parts by weight per hundred parts of rubber (phr)) in the rubbery matrix was the use of 200 phr TEOS and a water: TEOS mole ratio of 28.9:1 at room temperature for 24 h. The curing, mechanical, and thermal properties of the composite materials were also investigated. Increasing the in situ silica content increased the cure time and improved the mechanical properties of the composite. Compared to the NR vulcanizates filled with the commercial (ex situ formed) silica, the mechanical and thermal properties of the in situ silica composite material were significantly improved. Transmission electron microscopy revealed that the in situ formed silica particles were well distributed within the NR matrix, in contrast to the clumping of the ex situ formed commercial silica within the NR matrix. © 2014 Elsevier B.V. All rights reserved. | |
| keywords | |
|
|
|
| more information
_______________________________________________________________ |
| Synthesis of polyaniline/montmorillonite nanocomposites with an enhanced anticorrosive performance | |
| Piromruen P., Kongparakul S., Prasassarakich P. | |
|
|
|
| Abstract | |
| Polyaniline/montmorillonite (PANI/Mt) nanocomposites (1-7% (w/w) Mt based on the aniline content) were synthesized by in situ chemical oxidative polymerization with a 73.4-75.8% monomer conversion level. Fourier-transform infrared and scanning electron microscopy analyses confirmed the presence of Mt incorporation into PANI, whilst X-ray diffraction analysis revealed the exfoliated structure and that PANI was intercalated between the Mt layers. Thermogravimetric analysis revealed that the thermal properties of PANI and PANI/Mt composites were enhanced with increasing Mt levels. The corrosion protection of steel coated with PANI/Mt nanocomposites was investigated using cyclic voltammetry, and revealed that PANI/Mt nanocomposites showed an enhanced corrosion protection of steel against 1.0 M H2SO4 in comparison to that of a pure PANI coating. Increasing the Mt content in the PANI/Mt nanocomposites and the applied film thickness (10-50 μm) both improved the anticorrosive properties, presumably due to an increasing tortuosity of the diffusion pathway for corrosion agents. The best corrosion resistance of steel to salt spray was, however, obtained with a PANI/Mt nanocomposite with 5% (w/w) Mt when applied as a 50 μm thick film. © 2013 Elsevier B.V. All rights reserved. | |
| keywords | |
|
|
|
| more information
_______________________________________________________________ |
| Photosensitizing triarylamine- and triazine-cored porphyrin dimers for dye-sensitized solar cells | |
| Luechai A., Pootrakulchote N., Kengthanomma T., Vanalabhpatana P., Thamyongkit P. | |
|
|
|
| Abstract | |
| Two novel triarylamine- and triazine-cored porphyrin dimers were synthesized and investigated for their potential in dye-sensitized solar cells (DSSCs). Based on cyclic voltammetric analysis, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the target porphyrins were found to be in an appropriate range in the TiO 2-based DSSC systems. The device studies indicated the photovoltaic effects in the DSSCs based on both materials and the significant effect of their core units on the photovoltaic conversion efficiencies of the devices. © 2013 Elsevier B.V. All rights reserved. | |
| keywords | |
| Cyclic voltammetric; Dye-Sensitized solar cell; Dye-sensitized solar cells; Highest occupied molecular orbital; Lowest unoccupied molecular orbital; Photovoltaic conversion; Triarylamines; Triazine; Dimers; Electron energy levels; Photoelectrochemical cells; Photovoltaic effects; Porphyrins; Solar cells | |
|
|
|
| more information
_______________________________________________________________ |
| Synthesis of polyisoprene-montmorillonite nanocomposites via differential microemulsion polymerization and application of PIP-Mt in natural rubber | |
| Boonchoo P., Rempel G.L., Prasassarakich P. | |
|
|
|
| Abstract | |
| Polyisoprene-montmorillonite (PIP-Mt) nanocomposites with an average particle size of 30±7.2nm and narrow size distribution (20-50nm) were successfully synthesized via differential microemulsion polymerization. X-ray diffractometry analysis revealed that PIP was intercalated in the Mt layers expanding the d spacing of the Mt layer from 3.1nm to 3.8nm. The SDS (surfactant) concentration, isoprene monomer (IP) to water ratio and Mt loading were all found to affect the IP conversion level, and the solid content and particle size of the obtained PIP-Mt nanocomposites. An IP conversion level of 81% and a solid content of 20% were achieved at 0.25wt.% 2,2-azoisobutyronitrile (AIBN), 10wt.% Mt, 10wt.% SDS and an IP:H2O ratio of 0.24:1. These PIP-Mt nanocomposites could be used as an effective nano-filler in natural rubber (NR) latex for the preparation of NR/PIP-Mt composites, improving the mechanical properties compared to the unfilled NR. NR filled with PIP-Mt at 2wt.% showed a 1.6 and 1.1 fold higher tensile strength and a modulus of elasticity at 300% elongation, respectively. Furthermore, NR/PIP-Mt composites at 2wt.% Mt loading improved the thermal aging compared to unfilled NR, with an 87.6%, 96.2% and 84.0% retention of the tensile strength, elongation at break and modulus of elasticity, respectively compared to 52.5%, 88.9% and 58.8% for the unfilled NR. © 2013 Elsevier B.V. | |
| keywords | |
| Average particle size; Elongation at break; Isoprene monomers; Microemulsion polymerization; Nanofiller; Narrow size distributions; Solid contents; Water ratio; Clay minerals; Composite materials; Elastic moduli; Mechanical properties; Microemulsions; Nanoparticles; Particle size; Polymerization; Rubber; Tensile strength; Thermal aging; X ray diffraction analysis; Nanocomposites; composite; concentration (composition); elastic modulus; emulsion; isoprene; mechanical property; montmorillonite; particle size; particulate matter; polymerization; rubber; size distribution; surfactant; tensile strength | |
|
|
|
| more information
_______________________________________________________________ |
| A nitroaromatic fluorescence sensor from a novel tripyrenyl truxene | |
| Sam-Ang P., Raksasorn D., Sukwattanasinitt M., Rashatasakhon P. | |
|
|
|
| Abstract | |
| A new fluorophore containing a truxene core and three ethynyl pyrene peripheries is successfully synthesized by Sonogashira coupling. This compound exhibits superior emission properties compared to the parent truxene with quantum yields of 71 and 53% in CHCl3 and aqueous THF, respectively. In CHCl3, it shows a selective fluorescence quenching towards 2-nitrophenol with a detection limit of 1.54 ppm. When dissolved in aqueous THF, however, its fluorescence signal is selectively quenched by picric acid with a detection limit of 0.15 ppm. Since the absorption bands of these analytes overlap with the excitation wavelength of the fluorophore, the inner filter effect may be a significant cause of the fluorescent quenching. However, there is no constant correlation between the fraction of photons absorbed by the fluorophore and the emission integrals, therefore, other quenching mechanisms might also play important roles. The Stern-Volmer plots at different temperatures indicate a static or contact quenching of the fluorophore, which could be caused by the π-π interaction between the fluorophore and the electron-deficient analytes. © 2014 The Royal Society of Chemistry. | |
| keywords | |
| Fluorescence sensors; Truxene | |
|
|
|
| more information
_______________________________________________________________ |
| Picolinic diamide pincers for transition metal complexation and their electrochemical properties | |
| Seawpakorn S., Thamyongkit P., Keawsongsang W., Rojanathanes R. | |
|
|
|
| Abstract | |
| A series of novel molecular pincers was successfully synthesised by a copper-free Sonogashira coupling methodology. Complexation of the pincers with Cu(II), Ni(II) and Co(II) was performed in the presence of triethylamine. The formation of the desirable pincer ligands and complexes was confirmed by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy and mass spectrometry. Electrochemical properties of the complexes of the target pincer dimers investigated by means of cyclic voltammetry suggested that the pincer dimers should be able to serve as an electron donor for phenyl-C61-butyric acid methyl ester and as an electron acceptor for poly(3-hexylthiophene) in bulk heterojunction solar cells. © 2014 Taylor & Francis. | |
| keywords | |
|
|
|
| more information
_______________________________________________________________ |
| Thermal and mechanical properties of poly(lactic acid)/natural rubber blend using epoxidized natural rubber and poly(methyl methacrylate) as co-compatibilizers | |
| Ayutthaya W.D.N., Poompradub S. | |
|
|
|
| Abstract | |
| In order to improve the toughness of poly(lactic acid) (PLA), the incorporation of natural rubber (NR), which has a high elasticity and flexibility, can be used. However, the phase incompatibility between PLA and NR can cause poor mechanical properties of the final product in the absence of a compatibilizer because of their different polarities. In this research, epoxidized NR (ENR) and poly(methyl methacrylate) (PMMA) were used as co-compatibilizers for linking PLA/NR blends (PLA 100: NR 15 parts by weight per hundred parts of resin (phr)). Therefore, the aim of this research was to study the effect of the ENR/PMMA co-compatibilizer contents on the mechanical, thermal and morphological properties of the 100:15 phr PLA/NR blend. With 3 phr of ENR and 1 phr of PMMA, the elongation at break and impact strength of the 100:15 phr PLA/NR blend was significantly improved up to 1,813% and 362%, respectively. The thermal stability of the PLA/NR blend was also increased when using the co-compatibilizers. Interestingly, the PLA/NR blend containing the co-compatibilizer showed a high ultimate tensile strength after thermal aging at 100°C for 1 h with good mechanical properties. However, the percentage of crystallinity and glass transition temperature were decreased by the added co-compatibilizer. Finally, a good compatibility between the PLA and NR matrices could be clearly observed by scanning electron microscopy in the presence of the co-compatibilizer. © 2014 The Polymer Society of Korea and Springer Sciene+Business Media Dordrecht. | |
| keywords | |
| Esters; Mechanical properties; Polymer blends; Rubber; Scanning electron microscopy; Tensile strength; Thermal aging; Elongation at break; Epoxidized natural rubber; Morphological properties; Phase incompatibility; Poly lactic acid; Poly(methyl methacrylate) (PMMA); Thermal and mechanical properties; Ultimate tensile strength; Compatibilizers | |
|
|
|
| more information
_______________________________________________________________ |
| Polydiacetylene-nested porphyrin as a potential light harvesting component in bulk heterojunction solar cells | |
| Reanprayoon C., Gasiorowski J., Sukwattanasinitt M., Sariciftci N.S., Thamyongkit P. | |
|
|
|
| Abstract | |
| A meso-substituted zinc-porphyrin embedded in a polydiacetylene web was prepared and tested for its potential in bulk heterojunction solar cells (BHJ-SCs). Light assisted formation of the polyenynes from diacetylenes coupled to the meso-position of the porphyrin were observed after UV-radiation, as evidenced by double and triple bond Raman-bands at 1446 and 2080 cm -1, respectively, and via UV absorption enhancement at 530-600 nm. Using cyclic voltammetry, Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energy levels were determined to be in an appropriate range for the photoactive materials in BHJ-SCs. Indeed, photoluminescence quenching indicated energy and/or charge transfer when the target material was used as a donor in combination with phenyl-C 61-butyric acid methyl ester as acceptor in a blend. A photovoltaic effect of the BHJ-SCs was observed. © 2014 The Royal Society of Chemistry. | |
| keywords | |
| Bulk heterojunction solar cells; Highest occupied molecular orbital; Light-harvesting; Lowest unoccupied molecular orbital; Photoactive materials; Photoluminescence quenching; Polydiacetylenes; Target materials; Acetylene; Cyclic voltammetry; Electron energy levels; Heterojunctions; Porphyrins; Solar cells; Zinc compounds | |
|
|
|
| more information
_______________________________________________________________ |