High-temperature stabilization of polypropylene using hindered phenol–thioester stabilizer combinations,Part 1: Optimization and efficacy via nondust blends

The thermal degradation of unstabilized polypropylene has been investigated under long-term processing (twin extruder) and thermal aging at 150°C, with additive concentration studies on combinations of an established hindered phenolic antioxidant (pentaerythritol tetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) [S1010] and two popular thioesters (distearyl-3,3′-thiodipropionate [DSTDP] and didodecyl-3,3′-thiodipropionate [DLTDP]) using melt flow rate, carbonyl index and powder diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (FTIR), and differential scanning calorimetry (DSC) (oxidation induction time [OIT]) and ultimate embrittlement time (Fracture) on injection-molded test pieces. It was found that 20:80 phenol:thioester ratios provided the best long-term thermal stability (LTTS); however, this was the reverse for processing stabilization (80:20), underlining the antioxidant nature of the two stabilizers (long term vs. melt). Melt preblending of the stabilizers (to form a no-dust blend) gave rise to improved LTTS. DRIFTS FTIR indicated that there was an improvement in preblending the additives, which removed any volatile impurities. Increased additive dispersion and localized potential efficacy in the stabilization cycle is important, as well as possible improved addition of the additives to the extruder rather than fine powder. The data are discussed in relation to the long-term stabilization of polypropylene in high-temperature applications such as under the bonnet of automobiles where minimizing stabilizer losses and maximizing synergy are important.     

Experimental and numerical investigations on the heat production and thermal storage characteristics of rapid preparation amorphous powder activated coke

The heat production and thermal storage characteristics of rapid-preparation amorphous powder activated coke (RAC) were investigated. RAC was prepared by using a drop-tube reactor system. The natural oxidation characteristics of RAC were studied through combined TG–FTIR analysis and temperature-programmed experiment. Experimental results showed that CO and CO₂ were the main oxidation products of RAC in air, and that the oxidation reaction was in accordance with the Arrhenius equation and law of mass action. Thermal storage characteristics were studied through computational fluid dynamics simulation. The maximum excess temperature θ_max increases linearly with the increase of the initial temperature. The concentration fields of the products show that CO₂ is mainly concentrated in the upper part of the coke bin, and the CO generated by CO₂ at high temperature is mainly concentrated in the central part of the coke bin.     

Influence of Al3+ doping for V5+ on the structural,optical, thermal and electrical properties of V2-xAlxO5-δ (x=0–0.20) ceramics

This paper reports an investigation on the structure-properties correlation of trivalent metal oxide (Al₂O₃)-doped V₂O₅ ceramics synthesized by the melt-quench technique. XRD patterns confirmed a single orthorhombic V₂O₅ phase formation with increasing strain on the doping of Al₂O₃ in place of V₂O₅ in the samples estimated by Williamson-Hall analysis. FTIR and Raman investigations revealed a structural change as [VO₅] polyhedra converts into [VO₄] polyhedra on the doping of Al₂O₃ into V₂O₅. The optical band gap was found in a wide semiconductor range as confirmed by UV–visible spectroscopy analysis. The thermal and conductivity behavior of the prepared samples were studied using thermal gravimetric analysis (TGA) and impedance analyzer, respectively. All the prepared ceramics exhibit good DC conductivity (0.22–0.36 Sm^-1) at 400 ?C. These materials can be considered for intermediate temperature solid oxide fuel cell (IT-SOFC)/battery applications due to their good conductivity and good thermal stability.     

Optimization of structural,electrical, and magnetic properties of ytterbium substituted W-type hexaferrite for multi-layer chip inductors

The rare earth (Yb³⁺) substituted W-type hexagonal ferrites with composition CaPb_2-xYb_xFe₁₆O₂₇ (x = 0.0, 0.5, 1.0, 1.5, 2.0) were synthesized by a facile and cost-effective sol-gel auto combustion method with post heat treatment. The synthesized hexagonal ferrites were characterized by a variety of analytical techniques, and an impedance analyzer was used to investigate the effects of Ytterbium on structural, magnetic, spectral and dielectric properties. The relationship between their impedance, structure and dielectric properties was investigated. The X-ray diffraction patterns verify the presence of single-phase W-type hexagonal ferrites. Physical properties such as D_bulk (bulk density), D_xrd (X-ray density), and P (porosity) of the CaPb_2-xYb_xFe₁₆O₂₇ W-type hexagonal ferrites were calculated. The bulk density of all the samples was decreased, and X-ray intensity was increased with the Ytterbium replacement in the W-type hexaferrite. By adding Yb³⁺ ions, the lattice parameters, cell volume and X-ray density were reduced due to the substitution of ytterbium with smaller ionic radii compared to the lead ion with large ionic radii. The AC-conductivity was increased from (1.523 × 10^?5 to 6.699 × 10^?5) Ωcm^?1. The dielectric constant and tangent loss was found to decrease substantially. The magnetic properties were found to enhance by the substitution of Yb³⁺. The low coercivity value of Yb³⁺ substituted W-type hexagonal ferrites are suitable for magnetic recording media operated at a high-frequency regime. The enhancement of electrical, dielectric and magnetic characteristics suggests these materials as promising for multi-layer chip inductors (MLCIs) circuit applications.     

水热处理过程中伊敏褐煤微观结构的演变规律

褐煤水热处理可以脱除有害元素,降低n(O)/n(C)比,提高煤阶,有利于煤的洁净利用。利用高压反应釜对褐煤进行水热处理,采用拉曼光谱(Raman)和傅立叶红外光谱(FTIR)对处理后的煤样的化学结构进行分析,探索了不同温度水热处理后煤样微观结构的演变规律。结果表明:150℃水热处理时部分含氧官能团脱除,同时,部分脂肪族侧链断裂及不稳定大分子芳环结构分解形成小分子芳环结构,部分CO分解形成各类醚和羟基;当水热温度升至200℃,处理后褐煤的芳香度指数(R)和芳香结构稠合指数(DOC)上升,表明煤内缩合结构增加,同时,缺陷结构和杂环被去除,大分子芳环结构相对增加,CO大量分解;水热温度继续升高至250℃,褐煤发生氢转移反应导致脂肪族侧链增加;当水热温度达到300℃时,褐煤的芳环结构被破坏,交联结构和无定形碳增加。     

Detection of fresh palm oil adulteration with recycled cooking oil using fatty acid composition and FTIR spectral analysis

There is a growing concern over the food safety issue related to increased incidence of cooking oil adulteration with recycled cooking oil (RCO). The objective of this study was to detect fresh palm olein (FPO) adulteration with RCO using fatty acid composition (FAC) and Fourier-transform infrared spectroscopy (FTIR) spectral analyses combined with chemometrics. RCO prepared in the laboratory was mixed with FPO in the proportion ranged from 1% to 50% (v/v) to obtain the adulterated oil samples (AO). FACs for FPO, RCO, and AO were determined using gas chromatography equipped with a flame ionization detector (GC-FID). The compositions of most fatty acids in RCO lied within the normal ranges of Codex standard, except for C8:0, C10:0, C11:0, C15:0, trans C18:1, and polyunsaturated fatty acids (PUFAs), C20:5. PUFAs showed a consistent decreasing trend with increasing magnitude of change with respect to increasing adulteration level and thus might be a good indicator for detecting FPO adulteration with RCO. The evaluation parameters (coefficient of determination, root mean standard error) of the FTIR-partial least square (PLS) model of palm oil adulteration with recycled oil are R² = 0.995 and 3.25, respectively. For FTIR spectral analysis, the distinct variations in spectral regions and aberrations in characteristic bands between FPO and RCO were observed. The optimized PLS calibration model developed from normal spectral of the combined region at 3602–3398, 3016–2642, and 1845–650 cm^?1 overpredict the adulteration level. On the other hand, the discriminant analysis classification model was able to classify the FPO and AO into two distinct groups. Improvement of the principles of combined techniques in authenticating AO from fresh oil is beneficial as a guideline to detect adulteration in cooking oil.     

Experimental investigation on high temperature wettability and structural behaviour of SAW fluxes using MgO–TiO2–SiO2 and Al2O3–MgO–SiO2 flux system

To establish the relationship between wettability and structure with the change in SAW flux composition, the contact angle measurement study was performed at 1700 K. For MgO–TiO₂–SiO₂ and Al₂O₃–MgO–SiO₂ flux system the wetting behaviour was studied by evaluating the contact angle as well as surface tension properties. Sessile drop method was used to determine the wetting properties of SAW fluxes. Twenty-one SAW fluxes were designed & developed by applying mixture design approach of design of experiments. Chemical, phase and structural properties of SAW fluxes were measured using modern techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD) & Fourier Transform Infra-red spectroscopy (FTIR). As per the calculated contact angle value, different surface tension values for MgO–TiO₂–SiO₂ and Al₂O₃–MgO–SiO₂ flux system was calculated using Young's & Boni's equations. Using Dupre's equation the adhesion energy for twenty-one basic fluxes was also calculated. Measured contact angle value increased with increase in the TiO₂/MgO & TiO₂/Al₂O₃ flux ratio. Lower contact angle gives higher wettability between the flux and the heating substrate. With increase of TiO₂/SiO₂ ratio up to 1.5 to 2.0 the calculated surface tension value is decreasing while after that it is increased with increase in TiO₂/SiO₂ ratio.     

Optimization of process parameters and catalytic pyrolysis of Cascabela thevetia seeds over low-cost catalysts towards renewable fuel production

The present study deals with the optimization of process parameters and thermocatalytic pyrolysis of Cascabela thevetia (CT) seeds in a semi-batch cylindrical-shaped reactor. Response surface methodology (RSM) was employed for the optimization of process variables, while commercial catalysts CaO and Al₂O₃ were used for catalytic pyrolysis. From results, it was concluded that 525 °C temperature, 75 °C min⁻¹ heating rate, and 75 mL min⁻¹ flow of nitrogen yielded maximum pyrolytic liquid (45.26 wt%) while with the attendance of catalysts at 20 wt% increased the yield of pyrolytic liquid (49.12 wt% and 46.87 wt% for CaO and Al₂O₃ respectively). Optimization outcomes displayed that linear and quadratic terms of utilized factors were more noteworthy while interaction effects between the factors were not significant. Further, characterization of pyrolytic oil established that utilization of catalysts expressively enhanced its properties by reducing viscosity and boosted the calorific value. FTIR examination of pyrolytic oil showed that the attendance of phenols, ethers, alcohols, ketones, alkanes, acids, etc., while ¹H NMR results supported the FTIR results. GC-MS analysis showed a substantial reduction of phenols and oxygen-rich products and boost the development of alcohol and aldehydes in pyrolytic oil with the introduction of catalysts. These parameters indicate improved properties of pyrolytic oil, which intensified its bioenergy capabilities.