Materials Science Forum Vol. 846

Abstract: This study was carried out to determine the potential of waste cooking oil (WCO) in preparation of rigid polyurethane (PU) foam. The raw WCO was first filtered and adsorbed by using sugarcane bagasse activated carbon in order to purify the oil. Next, the adsorbed WCO was used to synthesize polyol via transesterification reaction. The WCO-based polyol was then combined with other chemicals at various ratios to form PU rigid foam. The adsorbed WCO showed the decrease in both free fatty acid percentage and viscosity, from 4.3 % to 0.77 % and from 106 mPa.s to 72.5 mPa.s, respectively. No alteration of functional group observed after adsorption as proven by FTIR spectroscopy. The FTIR spectrum of WCO-based polyol showed the formation of OH absorption peak and supported by the increase in hydroxyl value from 0 to 148.79 mgKOH/g after reaction. The formation of urethane linkages (NHCO) backbone in PU foam was confirmed using FTIR. The properties of PU foam are highly dependent on the chemical composition. The density and compressive strength of 60:54:90:40 of glycerol:water:polyol:amine polyurethane foam are 277.7 kg/m³ and 0.10 MPa, respectively. This study showed that WCO exhibit promising potential as raw material for PU formation.

Abstract: Here phosphorescent trinuclear copper (I) pyrazolate complexes ([Cu₃Pz₃]), synthesized from 3,5-dimethyl and 4-(3,5-dimethoxybenzyl)-3,5-dimethyl pyrazole ligands for complexes [Cu₃Pz₃]₁ and [Cu₃Pz₃]₂, were successfully impregnated into TiO₂ with concentration of 0.1 mol%. These luminescent photocatalyst composites ([Cu₃Pz₃]_{1 or 2}/TiO₂) gave 60% and 49% of dichlorophenoxyacetic acid (2,4-D) degradation after 1 h for [Cu₃Pz₃]₁/TiO₂ and [Cu₃Pz₃]₂/TiO₂, while TiO₂ only showed 48%. The higher activity observed on [Cu₃Pz₃]₁/TiO₂ than the TiO₂ would come from the efficient reduction of electron-hole recombination, while less dispersion of complex [Cu₃Pz₃]₂ with more rigid structure compared to complex [Cu₃Pz₃]₁ gave similar activity of the [Cu₃Pz₃]₂/TiO₂ to the TiO₂.

Abstract: Viscosity and rheological investigation are preliminary investigation to identify the mixture behaviour. The investigation found that SD mixtures behave like pseudoplastic behaviour and this showed that the mixture is the right solution to be a paint mixture. Scratch hatch is a conventional method to measure the adhesion of dried coating. SD15, SD10 and SD5 were showed the smooth edges of the cut. However, nanoscratch test is a high technology method measure the minimum depth of penetration on SD40 followed by SD25, SD15 and SD5. This showed that the SD40 is the hardest coating film. As for all adhesion performance, SD15 becoming the best coating film with medium standard evaluation.

Abstract: Synthetic metalloporphyrins have long been recognized either as functional models or mimics of the cytochrome P-450 enzymes and they are versatile compounds with potential use in drug delivery, catalysis and electronics. In the present study, the metalloporphyrin, (meso-tetra-(p-sulfonatophenyl)-porphyrinato)copper, CuTSPP was synthesized in the reaction between free-base porphyrin, meso-tetra (p-sulfonatophenyl)porphyrin, H₂TSPP and copper(II) acetate monohydrate. The materials were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet-Visible (UV-Vis) Spectroscopy, Proton Nuclear Magnetic Resonance (¹H NMR) Spectroscopy and Mass Spectrometry (MS) analysis. The FTIR spectra of both free-base porphyrin and CuTSPP showed the appearance of three pronounced bands indicating the presence of the salt form (R-SO₃Na) of the sulfonic acid group. Characterization of CuTSPP by UV-Vis spectroscopy confirmed that the insertion of copper into the free-base porphyrin was successful by the appearance of the Soret band and Q bands. The catalytic activity of CuTSPP was tested in the oxidation of 2,3,6-trimethylphenol (TMP) at 60 °C using hydrogen peroxide (H₂O₂) as oxidant. The reaction parameters including the reaction temperature and time have been optimized. The only product obtained by means of TMP oxidation with H₂O₂ using CuTSSP is 2,3,5-trimethylbenzoquinone (TMBQ), an important precursor for the industrial production of Vitamin E.

Abstract: Porous montmorillonite (PMMT) was derived from natural montmorillonite (MMT) through functionalization using 3-aminopropyltrimethoxysilane (APTMS) and intercalation with cationic potato starch as the template. Phosphotungstic acid (HPW) supported on PMMT was synthesized by wet impregnation method. The resulting PMMT showed remarkable increase in surface area from the low value of 191 m²g^‒1 for parent MMT to the high value of 930 m²g^‒1 for PMMT. Acidity studies by pyridine adsorption followed by FTIR spectroscopy showed that both MMT and PMMT possessed strong Lewis acid sites. In contrast, the surface acidity of HPW incorporated into PMMT was shown to be significantly enhanced by forming mainly Brönsted acid sites. The catalytic activity of these materials was evaluated in the Friedel-Crafts acylation of anisole with propionic anhydride. The PMMT/30HPW catalyst which possesses the highest number of Brönsted acid sites showed excellent catalytic activity giving selectivity as high as 95% toward the main product, p-methoxypropiophenone.

Abstract: First-principles study based on density functional theory (DFT) framework for structural, electronic and optical properties of titanium dioxide (TiO₂) in anatase and rutile phases are investigated. Anatase phase exhibits wide band gap compare to rutile phase. The partial and total density of states for TiO₂ (anatase and rutile) describes the occupying of titanium (Ti) and oxygen (O) atoms at each energy level. TiO₂ has a high dielectric constant to avoid the recombination process while its high refractive index provides the efficient of light diffusion. The optical absorption of TiO₂ occurs in ultraviolet (UV) light of the wavelength photon. The results from the first-principles calculations will be helpful to give an understanding about the properties of TiO₂ as promising photoanode in dye-sensitized solar cell (DSSC).

Abstract: The structural, electronic and optical properties of pure and neodymium (Nd) doped anatase titanium dioxide (TiO₂) are investigated via first-principles calculations within density functional theory (DFT) approach. The band gap reduces to ~0.398 eV when Ti⁴⁺ is substituted with Nd³⁺ in TiO₂ crystal structure. The presence of Nd 4f states in the conduction band of TiO₂ clarifies the reducing of the band gap. The dielectric constant and refractive index of Nd-doped TiO₂ increase compare to pure TiO₂. Nd-doped TiO₂ able to enhance light absorption to longer wavelength spectrum. The first-principles results obtained satisfy the criteria for Nd-doped TiO₂ to become feasible photoanode material in dye-sensitized solar cell (DSSC) device.

Abstract: The geometry optimization of the tetragonal supercell 1x1x2 (P4mm, 99 space group) of PZT and PSnZT were calculated using different exchange correlation functional such as Local Density Approximate (LDA-CAPZ) and Generalized Gradient Approximation (GGA-PBE & GGA-PBEsol).The calculation using functional GGA-PBEsol exhibits the most accurate values of lattice parameter and volume of structure relative to the experiment results with typical error of approximately 1% underestimate (only for PZT-as reference materials). The electronic band structure and density of state (DOS) were also studied in order to understand the electron density and hybrization between cation and anion in the compound. The density of state studies indicated existing of hybridizations among anion O 2p, cation Pb 6s/Sn 5s (special lone pair) and the Ti 3d/Zr 4d states of PZT and PSnZT compound. An indirect band gap was respectively obtained for both cubic PZT and PSnZT at the F-G and Q-G point with 3.154 eV and 2.571 eV.

Abstract: This paper presents an acousto-optics analysis on free space optical signals modulated by two distinguishable non-resonant acoustic waves. The acoustic waves were directed at two different directions and locations along a laser beam and created non-interference modulated optical signals. The photonics microphone deploys low-powered eye-safe continuous-wave 633-nm laser; high-speed photodiode and a series of Fourier lenses. Two transducers generating 20 Hz to 20 kHz acoustic waves were directed across the laser beam. The receiving modulated signal was filtered and amplified electronically by two sets of passive bandpass filter separated by a transimpedance amplifier and connected to a computer for analysis. The signal was further digitally filtered and amplified to enhance the signal-to-noise ratio via MATLAB software. These signals were analyzed in time and frequency domains using Fast Fourier Transform (FFT) and Spectrogram. It was found that the recorded signals demonstrated higher signal intensities for lower acoustic frequencies with digital signal-to-noise ratio (SNR) ranging from 10.77 to 71.92 for frequency of 1 kHz to 20 kHz and 20 Hz to 1 kHz respectively. The frequencies of both transducers were simultaneously swept through from 20 Hz and 20 kHz respectively. These scanning frequencies approached one another and crossover with no resonant frequency was observed. This illustrates that it is able to detect multiple acoustic signals for any given frequencies along the laser beam and found its applications in stealth sound detection and long range sound sensor. Though low-powered 1-mW laser was used, a relatively high signal-to-noise ratio with clear-recorded playback was achieved.