Ruksapong Kunanuruksapong

Preparation and properties of calcium oxide from eggshells via calcination

Duck eggs are one of the most versatile cooking ingredients in which residue eggshells are discarded. Raw duck eggshells were calcined at temperatures between 300 to 900 °C, for 1, 3, and 5 h. Both the raw and calcined duck eggshells were characterized by FTIR, STA, XRD, XRF, TEM, BET, a particle size analyzer, and an impedance analyzer. The proper calcination conditions are: 900 °C and 1 h, yielding calcium oxide with a purity of 99.06 % w/w. The calcium carbonate of the rhombohedral form (CaCO3) transforms completely into the calcium oxide or lime of the face centered cubic form (CaO) at 900 °C, as shown by XRD diffraction patterns. The transmission electron microscopy (TEM) images of the calcium oxide reveal a moderately good dispersion of nearly uniform particles. The calcium oxide has a white color, a spherical shape, high porosity, and narrow particles size distribution. The percentage of ceramic yield of the calcium oxide is 53.53, as measured by STA (TG-DTA-DTG). The calcium oxide has a N2 adsorption-desorption isotherm indicating the meso-porosity range. The dielectric constant and the electrical conductivity of the calcined calcium oxide are 35 and 1:0×10−6(Ω·m)−1, respectively, at the frequency of 500 Hz.

Interactions between CO and Poly(p-phenylene vinylene) as Induced by Ion-Exchanged Zeolites

The effects of zeolite type, ion-exchanged level, and ion type on the electrical conductivity responses of poly(p-phenylene vinylene) (PPV), doped poly(p-phenylene vinylene) (dPPV) and zeolite composites under CO exposures were investigated. The electrical sensitivity of dPPV/Cu+-ZSM5(Si/Al = 23) system shows a negative sensitivity value of −0.154, while the Na+ system gives a positive sensitivity of 1.48. Based on FTIR and TPD data, the positive response of PPV/Na+-ZSM5 stems from the CO molecules acting as a secondary dopant. On the other hand, the negative response of PPV/Cu+-ZSM5 originates from the fact that CO molecules are selectively adsorbed on Cu+ sites rather than C+ sites of doped PPV.

Electromechanical responses of dielectric elastomer composite actuators based on natural rubber and alumina

The deflection responses of the dielectric elastomer actuators are investigated under the electrical field strengths between 0 and 650 V/mm at room temperature (27°C). The Standard Thai Rubber 5L (STR 5L)/aluminum oxide (Al2O3) composite (60 wt% Al2O3) cross-linked with 1 wt% dicumyl peroxide (DCP)/Irganox 1076 and cured at 170°C starts to deflect toward the anode side at the yield electrical field strength of 200 V/mm; the degree of bending increases monotonically with increasing electrical field strength of up to 650 V/mm. As the applied electric field is released, the elastomer composite recovers its original position and shape. The X-ray diffraction pattern of the STR 5L/Al2O3 composite (60 wt% Al2O3) cross-linked with 1 wt% DCP/I 1076 and cured at 170°C suggests that the highly ionic conductive Al2O3 generates the dipole moments in addition to that of the elatomer matrix. Scanning electron microscope micrograph of the composite shows a fairly uniform distribution of alumina particles in the natural rubber (STR 5L) matrix.

Mechanical and Electrical Properties of Alumina/Natural Rubber Composites

The mechanical and electrical properties of natural rubber (STR 5L)/alumina (Al2O3) composites with dicumyl peroxide (DCP) functioning as the crosslinking agent and as the filler in the composites were investigated. SEM micrographs indicate that the alumina particles are moderately dispersed in the matrix and some thread-like structures form. Both dicumyl peroxide and the alumina particles act the bi-dispersed particles in the composites. The XRD patterns indicate that Al2O3 is of the β-phase polytype that possesses high ionic conductivity. The electrical conductivity of the composites with DCP loading increases by nearly two and three orders of magnitude, compared to those of the STR 5L/Al2O3 composite without DCP and the pristine natural rubber (STR 5L), respectively. The increase in the electrical conductivity originates from the strong C–C and the Al–O–C bonds, the ionic polarization of the alumina particles, and the induced dipole moments set up in the natural rubber matrix.

Electrical and Electrorheological Properties of Alumina/Natural Rubber (STR XL) Composites

The electrorheological properties (ER) of natural rubber (XL)/alumina (Al2O3) composites were investigated in oscillatory shear mode under DC electrical field strengths between 0 to 2 kV/mm. SEM micrographs indicate a mean particle size of 9.873 ± 0.034 µm and particles that are moderately dispersed in the matrix. The XRD patterns indicate Al2O3 is of the β-phase polytype which possesses high ionic conductivity. The storage modulus (G′) of the composites, or the rigidity, increases by nearly two orders of magnitude, with variations in particle volume fraction and electrical field strength. The increase in the storage modulus is caused the ionic polarization of the alumina particles and the induced dipole moments set up in the natural rubber matrix.

REMOVING EXTRACTABLE PROTEINS IN NATURAL RUBBER LATEX BY CALCIUM CHLORIDE FROM CHICKEN EGGSHELLS

Abstract Controlling the level of the extractable protein contents in a natural rubber latex is important to the sensitization of natural rubber latex products users. Allergies caused by latex products cause a serious problem in which the sweat removes proteins and allowing a skin contact causing allergic reactions. Calcium oxide from calcined chicken eggshells at 900 °C for 1 h was dissolved in 2M HCl (CaCl2) and used as the thickening agent in which it can modify the protein structure. The eggshells were characterized by the particle size analysis, the impedance analysis, simultaneous thermal analysis (STA), x-ray diffraction (XRD), and Fourier transform infrared spectra (FTIR). Calcium chloride (CaCl2) interacts with the protein molecules and the solvent ions through the hydrogen bonding and the electrostatic interactions driving the extractable protein toward the film surface. Sodium dodecyl sulphate was used as the stabilizer in the natural rubber latex film formation. The extractable protein content...

Dielectrophoresis Force and the Electromechanical Responses of Elastomers

In our research, we investigated the electrorheological responses and dielectrophoresis force of the six elastomers at various electric field strengths and temperatures. For the electrorheological responses, the effect of temperature, between 300 and 370 K, on the storage modulus responses (ΔG′2kV/mm) and on the dielectric constants of elastomers were investigated under applied electric field strengths varying from 0 to 2 kV/mm. The acrylic elastomers (AR70, AR71, and AR72) have positive storage modulus responses and sensitivities with increasing temperature and dielectric constant. In the case of styrene copolymers (SAR, SBS, and SIS), the storage modulus responses and sensitivities increase and attain the maximum at the glass transition temperature of the hard segment. We studied the dielectrophoresis forces of the six elastomers by measured deflection distance under various electric field strengths (0–600 V/mm) and calculated the force from non-linear deflection theory of the cantilever. The results show that the dielectrophoresis forces of the six elastomers increase with increasing electric field strength. The acrylic elastomer AR71 had the lowest electrical yield point (75 V/mm) and it generated the highest force (389 μN at E = 600 V/mm). On the other hand, SIS had highest electrical yield point (400 V/mm) and it generated the lowest force (67 μN at E = 600 V/mm). The dielectrophoresis forces depend on many factors, such as dielectricity, conductivity, and storage modulus of the elastomers.

Mechanical and electrical properties of alumina–natural rubber composites

Abstract The mechanical and electrical properties of natural rubber (NR)–alumina (Al2O3) composites crosslinked with dicumyl peroxide (DCP) were investigated. Scanning electron micrographs indicate the interaction of the C–C microstructure and that alumina particles are moderately dispersed in the matrix. The X-ray diffraction patterns indicate that Al2O3 is of the β phase polytype that possesses high ionic conductivity. The electrical conductivity of the composites with DCP is greater by nearly three orders of magnitude than that of NR–Al2O3 composites without DCP and pure NR. The increase in the electrical conductivity and the mechanical property is caused by the strong C–C bond, the tunnelling phenomenon and the ionic polarisation of the alumina particles acting as the dispersed phase in the elastomer matrix.

An Innovative Measurement of Extractable Proteins from Concentrated Latex Containing Eggshell Calcium Oxide Compounds by Near-Infrared Spectroscopy

ABSTRACT Near-infrared reflectance (NIR) spectroscopy, in the spectral range of 1100–2500 nm, was used to measure the amount of the directly extractable proteins (EP) where a small amount can cause a latex allergy to patients. The NIR spectra revealed an amino or a peptide (N-H) of the extractable proteins from the concentrated rubber latex added with sodium dodecyl sulphate (SDS) and calcium chloride, the latter being obtained from the pyrolysis of eggshells at 900°C for 2 hr and dissolving in 2 M HCl. The extractable proteins measured by NIR are equal to 5306.58 ± 1727.00 µg/g (0.53%) close to the value obtained by the modified Lowry method, which is 5566.02 ± 717.39 µg/g (0.56%). A partial least square regression model (PLSR) of the NIR spectra and the extractable protein contents yields a correlation coefficient of .72, a root mean square error of calibration (RMSEC) of 1298 µg/g, and a small bias value of −0.0002 µg/g. The absorbance peaks at the wavelengths of 1520 nm and 1980 nm are related to the first overtone N-H (υ1N-H) and the asymmetric combination of N-H, respectively. Furthermore, the absorbance peaks at the wavelengths of 1450 nm and 1920 nm correspond to the first overtone of O-H (υ1O-H) of the concentrated latex compounds. The results demonstrate the NIR spectroscopy potential as a fast and noninvasive measurement technique.

Dielectrophoresis force of poly(p-phenylene)/ acrylic elastomer under ac electric field

Abstract The effects of frequency and amplitude of an ac electric field on the deflection and dielectrophoresis force of an acrylic elastomer (AR71), styrene co-polymers (SAR and SBR) and polymer blends of doped poly(p-phenylene) (PPP) and acrylic elastomers (AR71) are investigated. The dielectrophoresis forces of the dielectric elastomers and blends are measured and determined by using a vertical cantilever fixture at various frequencies (0·3–60 Hz) and ac electric field strengths of 200, 300, 500, 600 and 800 Vpp mm−1. In addition, the effects of the thicknesses of the specimens and the particle concentration on the dielectrophoresis force are studied. The doped PPP particles are embedded in AR71 at particle concentrations of 1, 10 and 20 vol.-%. The forces are calculated from the non-linear deflection theory of the cantilever. The dielectrophoresis forces and deflection of the dielectric elastomers and the blends generally increase with increasing amplitude but slightly decrease with increasing frequency; they dramatically drop at the cutoff frequency. The cutoff frequencies are 7·84, 1·45 and 0·74 Hz for AR71, SAR and SBR respectively at the E of 800 Vpp mm−1 and thickness between 0·7 and 0·8 mm. After blending AR71 with the doped PPP, the cutoff frequencies of the 1, 10 and 20 vol.-% doped PPP improve to 18·51, 15·28 and 10·67 Hz respectively at the E of 800 Vpp mm−1 and thickness between 0·2 and 0·3 mm. The conductive polymer particles, acting as filler, are shown here to improve the electromechanical responses at high frequency.