Areerat, Surat

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Areerat, Surat
Alternative Name
Areerat, S.
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Email
surat.ar@kmitl.ac.th

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    Preparation of natural rubber-based polyol by oxidative degradation under supercritical carbon dioxide for flexible bio-based polyurethane foams
    (2016-11-01)
    Amnuaysin, Thidarat
    ;
    Buahom, Piyapong
    ;
    Areerat, Surat
    Nowadays, polyurethane foams play a key role in widespread applications, and their market demand is still growing globally. This work aims to prepare hydroxyl telechelic liquid natural rubber, a bio-based polyol, as a sustainable raw material and to enhance elastic properties of soft segment bio-based polyurethane foams. A hydroxyl telechelic liquid natural rubber with a viscosity-average molecular weight of 4.2 × 10<sup>3</sup>g/mol was successfully produced by oxidative degradation of natural rubber with hydrogen peroxide in the presence of supercritical carbon dioxide, then modifying the chain-end functionality to obtain hydroxyl number of 59 mg KOH/g. The functionality of hydroxyl telechelic liquid natural rubber was confirmed by FT-IR and <sup>1</sup>H-NMR. Bio-based polyurethane foams were then prepared by mixing the synthesized hydroxyl telechelic liquid natural rubber with commercial diisocyanate. Morphological properties and thermal stability of polyurethane foams were investigated.
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    The estimation of cell density in isotropic microcellular polymeric foams using the critical bubble lattice
    (2011-03-01)
    Buahom, Piyapong
    ;
    Areerat, Surat
    In this study, models for estimating the cell density of isotropic polymeric foams using the surface cell density were developed. The basic morphological unit cell for these models is a gas-filled pentagonal dodecahedral cell cavity. The critical bubble lattice model was introduced to associate the packing structure of the pentagonal dodecahedral cells with a face-centered cubic (FCC) packing structure, and the cell density was estimated. This model was then used to investigate the effect of nonperfect cell cross-sections as found in the micrographs of cell densities of foams. Two cases were examined: first, the ideal case of a perfect cross-section, and second, the actual case of a nonperfect cross-section. The plots of cell density versus surface cell density from recently published data show the effect of a nonperfect cross-section on the estimation of cell density within an FCC lattice with perfect and nonperfect cell cross-sections. The percentage average absolute deviation (AAD) showed that the nonperfect cell cross-sectional model reliably predicts the cell density of isotropic low-density foam with an AAD of 39.2%. The perfect cell cross-sectional model reliably predicts the cell density of isotropic high-density foam with an AAD of 57.2%. These new models are more reliable than the conventional model, which give AADs 59.4% for low-density foams and 62.4% for high-density foams. Furthermore, the isotropic foam index was introduced as a parameter to indicate the isotropic foam behavior. © The Author(s) 2010.
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    Enhancement of molecular weight reduction of natural rubber in triphasic CO2/toluene/H2O systems with hydrogen peroxide for preparation of biobased polyurethanes
    (2019-01-28)
    Duereh, Alif
    ;
    Boonchuay, Chokchai
    ;
    Buahom, Piyapong
    ;
    Areerat, Surat
    Molecular weight reduction of natural rubber (NR) with hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>) oxidizing agent is limited in biphasic water-toluene systems that is attributed to mass transfer. In this work, CO<inf>2</inf> was applied to the (aqueous H<inf>2</inf>O<inf>2</inf>)-(toluene-NR) systems with the objective of improving reaction efficiency. Experiments were performed on the reaction system with CO<inf>2</inf> at 12 MPa and at reaction temperatures and times of 60°C-80°C and 1 h-10 h to evaluate the reaction kinetics. CO<inf>2</inf> could enhance the NR molecular weight reduction by lowering the activation energy (from 121 kJ·mol<sup>-1</sup> to 38 kJ·mol<sup>-1</sup>). The role of CO<inf>2</inf> in the reaction system seems to be the formation of oxidative peroxycarbonic acid intermediate and promotion of mass transport due to the reduction in the toluene-NR viscosity and interfacial tension. The epoxidized liquid NRs (M<inf>n</inf>=4.9×10<sup>3</sup> g·mol<sup>-1</sup>) obtained from NR molecular weight reduction was further processed to prepare hydroxyl telechelic NR (M<inf>n</inf>=1.0×10<sup>3</sup> g·mol<sup>-1</sup>) and biobased polyurethane.