Chuanpit Khaokong | Prince of Songkla University (original) (raw)

Papers by Chuanpit Khaokong

Journal of Polymer Research, 2022

Anionic waterborne polyurethane (aWPU) composites were fabricated using hydoxytelechelic epoxidiz... more Anionic waterborne polyurethane (aWPU) composites were fabricated using hydoxytelechelic epoxidized natural rubber (HTENR) and silica, extracted from rice husk ash (RHA). Silica was then modified by poly(diallyldimethyl ammonium chloride) (PDDA), a cationic polymer. The PDDA content attached to the modified particles was about 4.43%. PDDA-SiO2 particles were smaller and the size distribution narrower than pristine SiO2 due to deagglomeration. The chemical structure of PDDA-SiO2 was confirmed by Fourier infrared spectroscopy (FTIR). PDDA-SiO2 particles were then loaded in aWPU at contents of 0.5 to 5.0% wt. using self-assembly by electrostatic interaction and hydrogen bonding between PDDA-SiO2 particle and aWPU. At PDDA-SiO2 loadings of 0.5 to 1.5% wt., aWPU/PDDA-SiO2 composites formed homogenous emulsions and transparent films. PDDA-SiO2 loadings of 3.0% wt. and 5.0% wt. produced PDDA-SiO2 agglomerations and filler clusters were seen in the obtained films due to poor dispersion of PDDA-SiO2 particles in the WPU matrix. PDDA-SiO2 incorporation increased Tg and raised the degradation temperature at 10% weight loss from 276 °C to 300 °C but reduced tensile strength compared to neat aWPU. Due to the insufficient interaction of aWPU and PDDA-SiO2 in case of physical mixing, sedimentation of PDDA-SiO2 particles in the PU matrix was observed but with PDDA modification the particles were uniformly embedded in nano-scale clusters.

Pour obtenir le grade de Docteur de l’Université du Maine Elaboration of electronic conductor com... more Pour obtenir le grade de Docteur de l’Université du Maine Elaboration of electronic conductor composite materials: study of physical and electronic properties Soutenance prévue le 18 Décembre 2008, devant le jury composé de:

Iranian Polymer Journal, 2019

From a zinc precursor of zinc nitrate hexahydrate and a precipitating agent of sodium hydroxide, ... more From a zinc precursor of zinc nitrate hexahydrate and a precipitating agent of sodium hydroxide, zinc oxide (ZnO) was hydrothermally synthesized. Using different formulations and different reaction conditions of time and temperature, the obtained ZnO presented two different morphologies: short prism-like, and flower-like. X-ray diffraction data confirmed the wurtzite structure of the obtained ZnO. The short prism ZnO presented a higher specific surface area than the flower-like and the conventional forms. The synthesized ZnO was then compounded with natural rubber (NR) latex at loading contents of 0.1-0.6 phr and NR with conventional ZnO (CZnO) at 1 phr which was used for comparison. The tensile and tear strength of all vulcanizates increased with increased loadings of ZnO, except the vulcanizate containing flower-like ZnO. NR vulcanized films containing short prism ZnO at 0.4 phr showed the highest mechanical properties and they were higher than those of the film containing CZnO at 1 phr. Modulus of all samples tended to increase with increasing content of the synthesized ZnO and it was comparable with the modulus of the sample contained CZnO. NR films containing either short prism or flower-like ZnO showed nearly the same elongation-at-break. The cross-link density of short prism ZnO-incorporated NR was higher than NR comprising flower-like ZnO and CZnO. Furthermore, the aging properties of films containing synthesized ZnO were comparable with the properties of rubber films containing CZnO. Hence, 0.4 phr short prism ZnO was the optimum content for the preparation of prevulcanized latex.

Http Www Theses Fr, 2008

The hydroxytelechelic oligoisoprene was synthesized according to well-controlled degradation proc... more The hydroxytelechelic oligoisoprene was synthesized according to well-controlled degradation procedure which has been recently developed in our laboratory, followed by the reduction of carbonyltelechelic cis-1,4-polyisoprene (CTPI) into hydroxytelechelic cis-1,4-polyisoprene (HTPI). Telechelic oligomers were characterized by FTIR, 1H-, 13C-NMR and SEC. Linear and crosslinked polyurethane films were synthesized from hydroxytelechelic cis-1,4-polyisoprene and diisocyanates or triisocyanates using dibutyltin dilaurate as catalyst. The modification of main chain by epoxidation or hydrogenation allows us to modify the properties of films. In this work, we have studied the possibility to use these kinds of polyurethanes as the polyelectrolyte matrix. The incorporation of ionic liquids, 1-butyl-y3-metylimidazolium hexafluorophosphate and trihexyltetradecylphosphonium chloride, in polymer films was done and the conductivity of films was measured by dielectric relaxation spectroscopy. The presence of epoxidation in the main chain of polyurethane allows us to incorporate more amount of ionic liquid in film. Type of ionic liquid has an effect on the compatibility and properties of polyurethane films. The thermal properties of films were determined by DSC and TGA. Moreover, the polyurethane films were used as supporting matrix in an electropolymerization of a conducting polymer. By this method, we can prepare the precise polyaniline spot according to the electrode on the polyurethane film support. In addition, new type chain extender containing pyrrole monomer unit was synthesized. Its structure was confirmed by NMR, mass spectroscopy and elemental analysis. Polyurethanes using this pyrrole derivative chain extender were prepared and the thermal properties were investigated. Finally, the electropolymerization of pyrrole unit in polyurethane structure was performed.

The main activity of our research group consists in the modification/ selective degradation of na... more The main activity of our research group consists in the modification/ selective degradation of natural rubber to obtain new precursors to employ as building bricks in the synthesis of new materials with tailor-made properties. Two methodologies have been developed two cut the long cis1,4-polyisoprene chains into small oligomers: degradative oxidation with periodic acid and a metathesis reaction using Grubbs II catalysts. The advantage of these controlled degradations is to obtain telechelic functionalized oligomers with a targeted molecular weight, low polydispersity and the stereoregular structure of cis-polyispoprene. A portfolio of oligomers with different chemical functions has been obtained using simple procedures and conditions, in view of industrial applications. After the presentation of the synthesis of some of these reactive oligomers, an overview of the polymers/ materials obtained from them will be given. Among others, oligomers have been modified by adding a RAFT (radic...

Advanced Materials Research, 2014

This work is preliminary studied of alumina-reinforced epoxidized natural rubber prepared via lat... more This work is preliminary studied of alumina-reinforced epoxidized natural rubber prepared via latex-mixing method without coupling agent. The effect of alumina content on distribution of filler and mechanical properties was investigated. Epoxidized natural rubber latex (ENR) was synthesized by in situ epoxidation of natural rubber using formic acid and hydrogen peroxide. The vulcanizing chemicals and alumina were then added in to ENR latex. The alumina content was varied from 10 to 75 phr. Prevulcanization at 70oC for 24 h and post-vulcanization at 110oC for 15 minutes was performed. The mixing time for a hour at mixing speed 600 rpm was chosen due to it shows the regular dispersion of filler in the matrix. The alumina content which can be added in epoxidized natural rubber decreased as epoxidation increased. The amount of alumina added was limited by the rigidity of high epoxidation content rubber. Modulus was increased with the increased of alumina content, whereas at alumina cont...

Acta Crystallographica Section C Crystal Structure Communications, 1998

The structures of the 1:3 mononuclear complexes of copper(I) and silver(I) iodide with diethylthi... more The structures of the 1:3 mononuclear complexes of copper(I) and silver(I) iodide with diethylthiourea (detu), namely, [CuI(C 5 H 12 N 2 S) 3 ] and [AgI(C 5 H 12 N 2 S) 3 ], are isomorphous. The metal atoms are approximately tetrahedrally coordinated to three S atoms and to one I atom.

Key Engineering Materials, 2012

Biodegradable polyurethane was synthesized using poly(DL-lactic acid) diol and hydroxytelechelic ... more Biodegradable polyurethane was synthesized using poly(DL-lactic acid) diol and hydroxytelechelic natural rubber as hydroxyl containing precursor, 1,4-butane diol as chain extender, isophorone diisocyanate and dibutyltin dilaurate as catalyst. Poly(DL-lactic acid) diol was prepared by condensation polymerization of DL-lactic acid using 1,4-butane diol as initiator and stannous octoate as catalyst. Hydroxyltelechelic natural rubber synthesized via oxidative degradation of natural rubber and then reduced carbonyl end group to hydroxyl group. Chemical structure of products was characterized by 1H-NMR. Molecular weight and polydispersity determined by SEC. Thermal properties was characterized by DSC and TGA. Segmented polyurethane show two Tgs and two degradation steps corresponding to natural rubber and poly(DL-lactic acid) segment. Polyurethane containing poly(lactic acid) more than 40%mol are become brittle. This result caused by brittle characteristic of PLA. Moreover, mechanical pro...

Materials Science Forum, 2011

A new type of polyurethane (PU) has been synthesized by using hydroxyl terminated liquid natural ... more A new type of polyurethane (PU) has been synthesized by using hydroxyl terminated liquid natural rubber (HTNR) and poly(e-caprolactone) (PCL) as a soft segment and toluene-2,4 diisocyanate (TDI) as a hard segment. This PU becomes a biodegradable and recyclable polymer. The PU samples were synthesized by solution polymerization. TDI/PCL polymerization was prepared in order to determine the appropriate NCO:OH ratio which evaluated from the molecular weight of derived PU and the ratios which were able to form a polymeric film. The suitable NCO:OH ratios were 0.84:1 – 1.20:1 and the Mn of the derived PUs was 3000-5500 g/mol determined by using GPC. PU from PCL-HTNR block copolymer was synthesized by varying molar ratio between PCL and HTNR. HTNR has been synthesized by epoxidation reaction and chain cleavage of natural rubber. The Mn of HTNR was in the range of 1700-8000 g/mol. 1H-NMR and FTIR were used to determine the functional group in order to verify the prepared HTNR and PU. Glass...

Macromolecular Symposia, 2010

Composite polyurethane/polyaniline (PU/PANI) films have been chemically prepared by oxidative in-... more Composite polyurethane/polyaniline (PU/PANI) films have been chemically prepared by oxidative in-situ polymerization of aniline inside the previously swelled PU film. Swelling kinetic studies have shown that for PU films the swelling degree of aniline is 25 wt.%. The dielectric and electrical properties of the composite films were measured using dielectric relaxation spectroscopy and four-probe method. Dielectric measurements as a function of temperature and frequency revealed the presence of a relaxation process for the composite PU/PANI-HCl film. This relaxation was explained in terms of interfacial polarization due to the double-layered structure of the composite film. The activation energy values found by dielectric and electrical measurements are close and this result confirms the conducting character of the PANI containing layer.

Journal of Polymers and the Environment, 2012

Novel polyurethanes were successfully synthesized by a one-shot polymerization. They contained po... more Novel polyurethanes were successfully synthesized by a one-shot polymerization. They contained poly(e-caprolactone) diol (PCL diol) and hydroxyl telechelic natural rubber (HTNR) as the soft segment. The effect of the NCO:OH molar ratio (0.75:1.00-2.25:1.00), chain extender and PCL:HTNR molar ratio (1:1, 0.7:0.3 and 0.3:0.7) on the thermal and mechanical properties of the resulting polyurethane were investigated. FTIR analysis showed the presence of urethane linkages and crosslinking or chain branching. The derived polyurethanes demonstrated excellent mechanical properties, which depended on their chemical composition. Their tensile behavior seemed to have typical elastomeric characteristics. Polyurethanes became amorphous and showed a phase separation between the PCL diol and HTNR segments. The phase separation between the soft and the hard segments was observed by the DMTA technique whereas DSC results showed only the glass transition temperatures of the soft segment. The longer and more flexible chain and non-polarity of HTNR was responsible of a decrease in the mechanical properties and transition temperatures.

Journal of Non-Crystalline Solids, 2010

Composite polyurethane/polyaniline and polyamide-6/polyaniline films were chemically prepared by ... more Composite polyurethane/polyaniline and polyamide-6/polyaniline films were chemically prepared by oxidative in situ polymerization of aniline inside the previously swelled matrix film. Swelling kinetic studies had shown that for polyurethane and polyamide-6 films the swelling degree of aniline was 25 wt.% and 15 wt.%, respectively. The dielectric and electrical properties of the composite films were established using dielectric relaxation spectroscopy and four-probe method. Dielectric measurements as a function of temperature and frequency revealed the presence of relaxation processes influenced by the nature of the polymer matrix, i.e. one relaxation process for the polyurethane based composite film and two relaxation processes for polyamide-6 based composite film. These relaxations were explained in terms of interfacial polarization caused by the polyaniline organisation as it was revealed by atomic force microscopy. Activation energy values obtained by dielectric and electrical measurements are close and this result confirms the conducting character of the polyaniline containing layer.

Journal of Applied Polymer Science, 2013

Bio-based polyurethanes (PU) containing poly(e-caprolactone) diol (PCL) and hydroxyl telechelic n... more Bio-based polyurethanes (PU) containing poly(e-caprolactone) diol (PCL) and hydroxyl telechelic natural rubber (HTNR) were synthesized. The effect of the diisocyanate structure and the molecular weights of diols on the mechanical properties of PU were investigated. Three different molecular structures of diisocyanate were employed: an aliphatic diisocyanate (hexamethylene diisocyanate, HDI), an aromatic diisocyanate (toluene-2,4-diisocyanate, TDI) and a cycloalkane diisocyanate (isophorone diisocyanate, IPDI). Two molecular weights of each diol were selected. When HDI was employed, a crystalline PU was generated while asymmetrical structures of TDI and IPDI provided an amorphous PU. The presence of crystalline domains was responsible of a change in tensile behavior and physical properties. PU containing TDI and IPDI showed a rubber-like behavior: low Young's modulus and high elongation at break. The crystalline domains in PU containing HDI acted as physical crosslinks, enhancing the Young's modulus and reducing the elongation at break, and they are responsible of the plastic yielding. The crystallinity increased the tear strength, the hardness and the thermal stability of PU. There was no significant difference between the TDI and IPDI on the mechanical properties and the physical characteristics. Higher molecular weight of PCL diol changed tensile behavior from the rubber-like materials to the plastic yielding. Thermal and dynamic mechanical properties were determined by using DSC, TGA and DMTA. V

Journal of Applied Polymer Science, 2011

Rubber toughened poly(lactic acid) (PLA) was prepared by blending with natural rubber (NR)-based ... more Rubber toughened poly(lactic acid) (PLA) was prepared by blending with natural rubber (NR)-based polymers. The blends contained 10 wt % of rubber and melt blended with a twin screw extruder. Enhancement of impact strength of PLA was primarily concernced. This study was focused on the effect of rubber polarity, rubber viscosity and molecular weight on mechanical properties of the blends. Three types of rubbers were used: NR, epoxidized natural rubber (ENR25 and ENR50), and natural rubber grafted with poly(methyl methacrylate) (NR-g-PMMA). Effect of viscosity and molecular weight of NR, rubber mastication with a two-roll mill was investigated. It was found that all blends showed higher impact strength than PLA and NR became the best toughening agent. Viscosity and molecular weight of NR decreased with increasing number of mastication. Impact strength of PLA/NR blends increased after applying NR mastication due to appropriate particle size. DMTA and DSC characterization were determined as well. V

Advanced Science Letters, 2013

ABSTRACT A series of polyurethane (PU) polymers have been synthesized using poly(ε-caprolactone) ... more ABSTRACT A series of polyurethane (PU) polymers have been synthesized using poly(ε-caprolactone) diol (PCL diol) and hydroxyl telechelic natural rubber (HTNR) as a soft segment. The hard segment included isophorone diisocyanate and 1[U+0003] 4-butanediol (BDO) that was added as a chain extender. The effect of the BDO and HTNR content was investigated in terms of the mechanical and thermal properties of the obtained PU. The presence of urethane linkage was verified by FTIR and found that crosslinked PU was obtained. The addition of BDO in the PCL diol-based PU increased the Young's modulus and tear strength but decreased the elongation at break resulting in a decrease in the tensile strength. By addition of a small amount of HTNR, the tensile properties and tear strength of PU increased significantly. With a further increase in the HTNR content, the tensile behavior of PU was changed from a tough to a soft polymer. The mixture of the PCL diol and HTNR used as the soft segment produced a promising bioplastic material with regard to an enhancement of biodegrability. The high crosslinking was attributed to there being no phase separation between the hard and the soft segment according to the results of the DSC and DMTA analysis. Hydrogen bonding between the PCL diol and the hard segment produced a high Tg .

Iranian Polymer Journal, 2020

Compatibility is a serious problem in silica-added natural rubber (NR) because of the difference ... more Compatibility is a serious problem in silica-added natural rubber (NR) because of the difference in the polarities of silica and NR. Thus, a coupling agent, such as silane, or a compatibilizer must be incorporated. In this work, amine-functionalized NR was synthesized by an in situ epoxidation process using performic acid and later modified with hexamethylene diamine (HMDA) by a ring-opening reaction. The effects of amine-modified epoxidized NR (ENR-HMDA) content on the cure characteristics, physical and mechanical properties of various NR blends (NR/ENR-HMDA) without filler were studied. ENR-HMDA enhanced the vulcanization process. The maximum torque of compounds increased with the corporation of ENR-HMDA and scorch time and cure time decreased. The cure rate index of NR/ENR-HMDA increased by 98%. All vulcanized rubber blends showed the strain-induced crystallization at high extension. Mechanical properties and crosslink density of the blends were higher than those of NR and NR incorporated with unmodified ENR. Tensile strength was 61% and 43% higher than that for NR and NR/ENR, respectively. The NR/ENR-HMDA blends showed a single T g that indicated the miscibility of both components. The developed ENR-HMDA compound can be used to improve the compatibility of NR and fillers which would enable the fabrication of a wide range of rubber products.