Influence Of Processing Temperature Research Articles

XPS Study of the Effect of Low Temperature Ammonia Plasma Treatment on PAN-Based Carbon Fiber

In order to obtain the maximum amounts of amino functional groups with low temperature ammonia plasma surface treatment on PAN-based carbon fiber, the influence of processing temperature and time were researched in this paper. By using X-ray photoelectron spectroscopy (XPS) method, the-NH2(-NH)/ C-C atomic ratio of untreated and treated fiber was analyzed. Results show that processing temperature is a key factor as intensity of the N1s peak increases gradually while processing temperature improves, furthermore, when temperature is 175°C, the most intensity of the N1s peak is obtained. Low temperature ammonia plasma surface treatment method has given a new approach to surface functionalized treatment of carbon fiber.

Influence of process temperature on drying kinetics, physicochemical properties and antioxidant capacity of the olive-waste cake

The objective of this study was to determine the effect of drying temperature on the drying kinetics, proximal analysis, energy consumption and the antioxidant capacity of the olive-waste cake “Picual” variety from 40 to 90°C. Evaluation of proximal analysis evidenced the influence of temperature on the waste parameters. Values of effective moisture coefficients were in the range of 1.97–6.05×10−9m2s−1 under the studied conditions. Activation energy was found to be 28.24kJmol−1. The Weibull model was successfully applied (r2>0.973). Specific energy consumption decreased as temperature increased, showing the effect of drying times over temperature. Although dehydrated samples decreased the initial total phenolic content, significant differences were not detected. Effects of drying temperatures did not present significant differences on antioxidant capacity (ORAC and DPPH) when compared to fresh samples. The oleic acid (main fatty acid in fresh samples) presented a maximum increased at 90°C.

Effect of Rehydration Temperature on Functional Properties, Antioxidant Capacity and Structural Characteristics of Apple (Granny Smith) Slices in Relation to Mass Transfer Kinetics

AbstractApple slices dried at 60C were rehydrated at 20, 40 and 60C to analyze the influence of processing temperature on quality attributes and rehydration kinetics. Diffusion coefficient increased with process temperature from 1.36 to 2.37 × 10−9 m2/s. The Weibull model obtained the best fit quality for the experimental data based on statistical test, chi square. Color was not recovered during rehydration and the results indicated that the use of low temperatures is more adequate. Water‐holding capacity decreased, while rehydration ratio increased with increasing rehydration temperature, indicating structural modifications. Increasing rehydration temperatures led to a reduction in the glass transition temperature and hardness values of samples. The radical‐scavenging activity showed higher antioxidant activity at higher rehydration temperatures rather than at lower temperatures. It was found that rehydration temperature modifies the cell structure and antioxidant capacity of final product.

Influence of Processing Temperature on Properties of Sr(Fe0.5Nb0.5)O3 High Dielectric Ceramics

Influence of processing parameters, calcination and sintering temperatures, on the properties of Sr(Fe0.5Nb0.5)O3 samples were investigated The Sr(Fe0.5Nb0.5)O3 ceramics were fabricated by a solid-state reaction method. X-ray diffraction analysis revealed that pure perovskite phase of SFN powders was observed for the calcination temperatures ≥1000°C. However, all SFN ceramics showed the pure perovskite phase. Average grain size increased with increasing sintering temperature, where the hardness value was related with grain size. The dielectric properties examination indicated that increase of the sintering temperature is effective in improving dielectric constant of the SFN ceramics.

Effect of processing temperatures on characteristics of surface layers of low temperature plasma nitrocarburized AISI 204Cu austenitic stainless steel

The influence of processing temperatures on the surface characteristics of AISI 204Cu austenitic stainless steel was investigated during a low temperature plasma nitrocarburizing. The resultant layer was a dual-layer structure, which comprises a N-enriched layer on the top of C-enriched layer. The surface hardness and the layer thickness increase up to about HV0.05 1000 and 20 μm with increasing temperature. The specimen treated at 400 °C shows a much enhanced corrosion resistance compared to the untreated steel. A loss in corrosion resistance was observed for specimens treated at temperatures above 430 °C due to the formation of Cr2N.

Preparation and Evaluation of Sustained-Release Matrix Tablets Based on Metoprolol and an Acrylic Carrier Using Injection Moulding

Sustained-release matrix tablets based on Eudragit RL and RS were manufactured by injection moulding. The influence of process temperature; matrix composition; drug load, plasticizer level; and salt form of metoprolol: tartrate (MPT), fumarate (MPF) and succinate (MPS) on ease of processing and drug release were evaluated. Formulations composed of 70/30% Eudragit RL/MPT showed the fastest drug release, substituting part of Eudragit RL by RS resulted in slower drug release, all following first-order release kinetics. Drug load only affected drug release of matrices composed of Eudragit RS: a higher MPT concentration yielded faster release rates. Adding triethyl citrate enhanced the processability, but was detrimental to long-term stability. The process temperature and plasticizer level had no effect on drug release, whereas metoprolol salt form significantly influenced release properties. The moulded tablets had a low porosity and a smooth surface morphology. A plasticizing effect of MPT, MPS and MPF on Eudragit RS and Eudragit RL was observed via DSC and DMA. Solubility parameter assessment, thermal analysis and X-ray diffraction demonstrated the formation of a solid solution immediately after production, in which H-bonds were formed between metoprolol and Eudragit as evidenced by near-infrared spectroscopy. However, high drug loadings of MPS and MPF showed a tendency to recrystallise during storage. The in vivo performance of injection-moulded tablets was strongly dependent upon drug loading.

Phase transformation kinetics of calcium sulfate phases in strong CaCl2[sbnd]HCl solutions

Hydrochloric acid is a key reagent in many leaching operations. A main aspect of process economics is the ability to efficiently recover the hydrochloric acid. This paper discusses phase transformation kinetic aspects relating to a continuous, three stage HCl regeneration process based on the reaction of CaCl2 solution, which is a by-product of the mineral leaching process, with sulfuric acid. The influence of process temperature (40°C to 90°C), solution composition (0.25 to 4.97mol/L CaCl2, 0 to 9.43mol/L HCl) and presence of 5mol% calcium sulfate anhydrite (AH) seed on the induction time and speed of transformation of the metastable phases calcium sulfate dihydrate (DH) and calcium sulfate α-hemihydrate (α-HH) to anhydrite (AH) were investigated. The selected reaction environment reflects steady state conditions of the three stages of the HCl regeneration process. The results show the lifetime of metastable phases (DH, α-HH) to decrease with increased temperature and increased HCl concentration. Furthermore, it was found that the presence of AH seed shortens the induction time preceding the onset of transformation to this phase. The obtained phase quantity vs. time relationships suggest a dissolution–precipitation mechanism for the DH to α-HH transformation and a topotactic nucleation and growth mechanism for the α-HH to AH transformation. The obtained results allow the definition of temperature, concentration and time conditions to facilitate the production of the valuable DH and α-HH phases, while avoiding the formation of fibrous AH, which renders solid–liquid separation non-operational.

Steam gasification of waste tyre: Influence of process temperature on yield and product composition

An experimental survey of waste tyre gasification with steam as oxidizing agent has been conducted in a continuous bench scale reactor, with the aim of studying the influence of the process temperature on the yield and the composition of the products; the tests have been performed at three different temperatures, in the range of 850–1000°C, holding all the other operational parameters (pressure, carrier gas flow, solid residence time). The experimental results show that the process seems promising in view of obtaining a good quality syngas, indicating that a higher temperature results in a higher syngas production (86wt%) and a lower char yield, due to an enhancement of the solid–gas phase reactions with the temperature. Higher temperatures clearly result in higher hydrogen concentrations: the hydrogen content rapidly increases, attaining values higher than 65% v/v, while methane and ethylene gradually decrease over the range of the temperatures; carbon monoxide and dioxide instead, after an initial increase, show a nearly constant concentration at 1000°C. Furthermore, in regards to the elemental composition of the synthesis gas, as the temperature increases, the carbon content continuously decreases, while the oxygen content increases; the hydrogen, being the main component of the gas fraction and having a small atomic weight, is responsible for the progressive reduction of the gas density at higher temperature.

Inductive hot-pressing of titanium and titanium alloy powders

Inductive hot-pressing is a field-assisted sintering process (FAST) in which an electrical current is used to enhance the densification of the powder. Inductive hot-pressing could be employed to enable titanium powder to reach a higher density in less time than the pressing and sintering process. In this study, titanium and titanium alloy powders with different features were processed by means of inductive hot-pressing. The influence of processing temperature on density, microstructure, quantity of interstitial elements and hardness was investigated. Generally, practically fully dense materials were obtained without any carbon pick-up, even if the materials were in contact with the graphite matrix during processing. Nevertheless, there was an increment of the nitrogen content and some oxygen pick-up, especially for the powders with smaller particle size. Hardness is not significantly affected by the pressing temperature, but it strongly depends on the amount of interstitials.

Dispersion of particulate clusters via the rapid vaporization of interstitial liquid

A method for the dispersion of particle clusters driven by the pressure generated from the volatilization of interstitial liquid is described. To demonstrate the method, carbon black agglomerates were heated to induce the rapid evaporation of incorporated water or acetone, which resulted in breakage of the particle cluster. Measurements of the resulting fragment size distribution demonstrate the influence of processing temperature and type of incorporated liquid on the dispersion process.

Influence of Processing Temperature on the Failure Behavior of Fabricated Composites

Abstract: Composite materials are playing a greater role in engineering application due to their optimized structure and mechanical characteristics. Study here aims at composite design which enables the fabricated composite to have excellent mechanical behavior even in extremely corrosive environment, for example, environment with extremely high ozone gas concentration. To take advantage of the great anticorrosion property of pure aluminum (Al), PET thin film coated with pure aluminum (Al) on its surface has been introduced as the top layer of the fabricated composite with polyester textile as the middle layer. To bond these layers together, the composites with this sandwiched structure are manufactured at different temperature. Main purpose of the study is to evaluate the influence of processing temperatures on the mechanical properties of the manufactured composites, and on their failure behavior. In this way, optimized processing temperature may be found.

Rehydration Capacity of Chilean Papaya (Vasconcellea pubescens): Effect of Process Temperature on Kinetic Parameters and Functional Properties

Slabs of Chilean papaya hot air-dried at 60 °C were rehydrated at 20, 40, 60, and 80 °C to study the influence of process temperature on mass transfer kinetics during rehydration. Diffusive and empirical models were selected to simulate the experimental rehydration curves. All models parameters showed dependence with temperature, thus activation energy could be estimated according to an Arrhenius-type equation. Among the applied models, Weibull provided the best fit for each rehydration curve based on the statistical tests RMSE, SSE, and chi-square. According to these results, this model could be used to estimate the rehydration time of Chilean papaya. In addition, rehydration ratio and water-holding capacity were analyzed. Both indices showed a decrease with increasing rehydration temperature indicating modification of the papaya cell structure due to thermal treatment which resulted in a reduction of the rehydration ability, in particular at high rehydration temperatures.

Effects of Processing Temperature and Chemical Treatment on Tensile Strength of Kenaf Fiber - Reinforced Polypropylene Waste Composites

In this research, the influence of processing temperatures and fiber chemical treatments to mechanical properties of polypropylene (PP) waste – kenaf fiber composites was investigated. Results from experimental and theoretical calculation of composite tensile strength were compared. The composites were made of PP wastes and unidirectional kenaf fiber, and manufactured by hot press molding. The processing temperature variations were 175 oC, 185oC and 195 oC. The chemical treatment used were alkaline and permanganate treatment. Kenaf fiber – PP composites were successfully made with the void volume fraction less than 5%, maximum fiber volume fraction 48% and maximum longitudinal tensile strength 110 MPa or 238% higher than PP’s strength. For non- and alkali treated fiber composites, 185oC was the optimum processing temperature. Elevated processing temperature up to 195oC could decrease composite strength due to the degradation of fiber-matrix interface. The effect of permanganate treatment did not significantly affect the composites strength. However, the improvement of interfacial properties at elevated temperature was found by the use of permanganate treatment.

Influence of Processing Temperature on Boriding of SUS304 Stainless Steel by Al Added Fused Salt Bath

Influence of Processing Temperature on Boriding of SUS304 Stainless Steel by Al Added Fused Salt Bath

SUS304ステンレス鋼のB添加溶融塩浴を用いたほう化処理に及ぼす処理温度の影響

The austenitic stainless steel is excellent in corrosion resistance, toughness, and workability. But it is inferior to hardness and wear resistance. However, because it is not possible to stiffen by quenching, the development of the method of improving wear resistance is required. Recently, boriding has attracted extensive attention as surface stiffening processing of plain steel. In this research, the influence of processing temperature on the formation layer of SUS304 steel by B added fused salt bath was examined. Boriding were performed in molten borax which contained 4 mass%B at processing temperatures of 1123~1223 K (processing time of 1800 s). As a result of the examination, the hardness of the boriding layer becomes about 2000 HV when the processing temperature of 1223 K. Also the wear resistance too has improved remarkably. Furthermore, it was understood that the formation layer on the surface was FeB, and, additionally, consisted of compounds such as Fe, Cr, and B from the Vickers hardness and the analysis of the X-ray diffraction measurement.

Influence of processing temperature on the water vapour transport properties of wheat gluten based agromaterials

The influence of processing conditions (thermoforming temperature) on water vapour transport properties (permeability, sorption and diffusion) of wheat gluten-based films was studied in relation to structural properties (cross-linking degree of the wheat gluten matrix). Increasing temperature from 80°C to 120°C led to a significant decrease in material swelling in high moisture environment and a WVP reduction mainly due to a decrease in diffusivity but without important effect on the moisture sorption isotherms. This was attributed to a higher cross-linking degree of protein network for film thermoformed at 120°C, with a limited mobility and less possibilities of rearrangement in high moisture conditions.

2Mg–Fe alloys processed by hot-extrusion: Influence of processing temperature and the presence of MgO and MgH 2 on hydrogenation sorption properties

2Mg–Fe alloy powder produced by high-energy ball milling was processed by hot extrusion at temperatures of 200 °C and 300 °C to produce bulk samples. The alloys were hydrogenated for 24 h under hydrogen pressures of 24 bar (to produce the Mg 2FeH 6 phase) and 15 bar (to produce a mixture of MgH 2 + Mg 2FeH 6 phases), respectively. After the hydrogenation treatments, the complex hydride Mg 2FeH 6 was identified in both conditions, while the MgH 2 and MgO phases were observed only after extrusion at 200 °C. Desorption temperatures varied with the extrusion conditions; extrusion at 300 °C resulted in a desorption onset temperature about 68 °C lower than that of samples extruded at 200 °C, and about 200 °C lower than that of commercial MgH 2. Extrusion at the lower temperature did not change the number of stored defects (point defects, dislocations, voids, stacking faults, vacancies and others) produced in the milling process and increased the preferential sites for hydride nucleation, increasing the hydrogen storage capacity. The presence of MgO produced the beneficial effect of grain boundary pinning, but delayed the onset temperature of desorption. The combined presence of MgH 2 and Fe after hydrogenation at 15 bar seems to play a catalytic role that considerably hastened the Mg–H reactions and increased the desorption kinetics. However, the desorption kinetics in both conditions was still low.

Influence of equal channel angular extrusion processing parameters on the microstructure and mechanical properties of Mg–Al–Y–Zn alloy

An as-cast Mg–Al–Y–Zn alloy was successfully processed by equal channel angular extrusion (ECAE) in the temperature range of 225–400 °C, and the influences of processing temperature on the microstructure and mechanical properties were investigated. The use of back pressure during one-pass ECAE of Mg–Al–Y–Zn alloy was favorable for eliminating the undeformed area in the billet. At the processing temperature below 250 °C, the microstructures were characterized by unrecrystallised structure and the precipitated phase Mg 17Al 12 was elongated along the extrusion direction. With increasing processing temperature to 350 °C, a large number of recrystallised grains were obtained. Increasing processing temperature promoted workability but led to decrease in the strength of Mg–Al–Y–Zn alloy. Then billets of as-cast Mg–Al–Y–Zn alloy were extruded at different numbers of ECAE passes. It was found that the microstructure was effectively refined by ECAE and mechanical properties were improved with numbers of ECAE passes increasing from one-pass to four passes. However, strengths decreased slightly after five passes though the grain size decreased considerably.

Development and evaluation of injection-molded sustained-release tablets containing ethylcellulose and polyethylene oxide

Purpose: It was the aim of the present study to develop sustained-release matrix tablets by means of injection molding of ethylcellulose (EC) and polyethylene oxide (PEO) mixtures and to evaluate the influence of process temperature, matrix composition, and viscosity grade of EC and PEO on processability and drug release. Methods: Formulations consisting of metoprolol tartrate (MPT, concentration: 30%), EC plasticized by dibutyl sebacate, and PEO were extruded and consequently injection molded into tablets. The influence of process temperature (120°C and 140°C), matrix composition, viscosity grade of EC (4, 10, 20, 45, and 100 mPa·s) and PEO (7 × 106, 1 × 106, and 1 × 105 Mw) on processability and drug release was determined. Results: Formulations consisting of 70% EC and 30% MPT showed incomplete drug release, whereas drug release was too fast for formulations without EC. Higher PEO concentrations increased drug release. Formulations containing 30% metoprolol, EC, and different concentrations of PEO showed first-order release rates with limited burst release. Drug release from direct compressed tablets showed faster drug release rates compared to injection-molded formulations. There was no clear relationship between the molecular weight of EC and drug release. The melting endotherm (113.9°C) of MPT observed in the differential scanning calorimeter thermogram of the tablets indicated that a solid dispersion was formed which was confirmed by X-ray diffractogram. X-ray tomography demonstrated a difference in pore structure between tablets processed at 120°C and 140°C. Conclusion: It was concluded that injection molding can be applied successfully to develop sustained-release PEO/EC matrix tablets.

Influence of processing temperature on microstructure and microhardness of copper subjected to high-pressure torsion

Cu samples were subjected to high-pressure torsion (HPT) with up to 6 turns at room temperature (RT) and liquid nitrogen temperature (LNT), respectively. The effects of temperature on grain refinement and microhardness variation were investigated. For the samples after HPT processing at RT, the grain size reduced from 43 μm to 265 nm, and the Vickers microhardness increased from HV52 to HV140. However, for the samples after HPT processing at LNT, the value of microhardness reached its maximum of HV150 near the center of the sample and it decreased to HV80 at the periphery region. Microstructure observations revealed that HPT straining at LNT induced lamellar structures with thickness less than 100 nm appearing near the central region of the sample, but further deformation induced an inhomogeneous distribution of grain sizes, with submicrometer-sized grains embedded inside micrometer-sized grains. The submicrometer-sized grains with high dislocation density indicated their nonequilibrium nature. On the contrary, the micrometer-sized grains were nearly free of dislocation, without obvious deformation trace remaining in them. These images demonstrated that the appearance of micrometer-sized grains is the result of abnormal grain growth of the deformed fine grains.