scholarly journals Sintering Reaction and Pyrolysis Process Analysis of Al/Ta/PTFE

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1469 ◽  
Author(s):  
Jun Zhang ◽  
Junyi Huang ◽  
Yuchun Li ◽  
Qiang Liu ◽  
Zhongshen Yu ◽  
...  
Keyword(s):  
Carbon Black ◽  
Process Analysis ◽  
Chemical Properties ◽  
Test Sample ◽  
Product Formation ◽  
Exothermic Peak ◽  
Thermal Reaction ◽  
Vacuum Sintering ◽  
Reactive Material ◽  
Temperature Range

When the Al/Ta/PTFE reactive material was sintered at 360 °C in a vacuum sintering furnace, it was found that the material reacted to form a soft fluffy white substance and carbon black. To explore the reaction process further, powder samples of pure PTFE, Al/PTFE, Ta/PTFE and Al/Ta/PTFE, and molded cylindrical specimens were prepared. A TG-DSC test was carried out on the thermal reaction of four reactive materials, and XRD phase analysis was conducted on the white product, formed by the sintering reaction and the residue of the TG-DSC test sample, based on which of the pyrolysis processes and reaction mechanisms were analyzed. The results show that Ta and PTFE could have a chemical reaction at sintering temperature (360 °C) to form soft and fluffy white material TaF3 and carbon black, which can overflow the surface of the specimen and cause cracking of the specimen, which is tightly pressed. Since no obvious exothermic peak showed up on the TG-DSC curve, the composition of the residue of TG-DSC sample at different temperatures was tested and TaF3 was detected in the residue at 350 °C and 360 °C, indicating that Ta began to react with PTFE at a temperature range of 340–350 °C. According to the chemical properties and product formation of Ta, it could be speculated that the reaction mechanism between Ta and PTFE involves the PTFE decomposing first, then the fluorine-containing gas product reacting with metal Ta. According to the temperature range of the reaction, it is estimated that PTFE starts to decompose before 500 °C, but it is not detected effectively by TG-DSC, and the introduction of Ta could also affect the decomposition process of PTFE.

scholarly journals Assessment of Graphene Oxide and Nanoclay Based Hybrid Filler in Chlorobutyl-Natural Rubber Blend for Advanced Gas Barrier Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1098
Author(s):  
Jibin Keloth Paduvilan ◽  
Prajitha Velayudhan ◽  
Ashin Amanulla ◽  
Hanna Joseph Maria ◽  
Allisson Saiter-Fourcin ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Carbon Black ◽  
Natural Rubber ◽  
Gas Permeability ◽  
Chemical Properties ◽  
Barrier Properties ◽  
Hybrid Filler ◽  
Physical And Chemical ◽  
Chlorobutyl Rubber ◽  
And Chemical Properties

Nanomaterials have engaged response from the scientific world in recent decades due to their exceptional physical and chemical properties counter to their bulk. They have been widely used in a polymer matrix to improve mechanical, thermal, barrier, electronic and chemical properties. In rubber nanocomposites, nanofillers dispersion and the interfacial adhesion between polymer and fillers influences the composites factual properties. In the present work, a comparison of the hybrid effects of carbon black with two different nanofillers (graphene oxide and nanoclay) was studied. The 70/30 composition of chlorobutyl rubber/natural rubber elastomer blend was taken as per the blend composition optimized from our previous studies. The hybrid effects of graphene oxide and nanoclay in dispersing the nanofillers were studied mainly by analyzing nanocomposite barrier properties. The results confirm that the combined effect of carbon black with graphene oxide and nanoclay could create hybrid effects in decreasing the gas permeability. The prepared nanocomposites which partially replace the expensive chlorobutyl rubber can be used for tyre inner liner application. Additionally, the reduction in the amount of carbon black in the nanocomposite can be an added advantage of considering the environmental and economic factors.

Identification of Amber and the Copal under Heat Pressurized Process

2012 ◽  
Vol 554-556 ◽  
pp. 2112-2115
Author(s):  
Hui Li ◽  
Xuan Wang ◽  
Yong Zhu ◽  
Qin Ren
Keyword(s):  
Chemical Properties ◽  
Peak Position ◽  
Exothermic Peak ◽  
Endothermic Peak ◽  
Scanning Calorimetry ◽  
Natural Resin ◽  
Before And After ◽  
Artificial Heat ◽  
Physical And Chemical ◽  
And Chemical Properties

Amber and copal belong to the natural resin, which are similar and transitional in the physical and chemical properties. The artificial heat-pressurized treatment is contributed to the polymerization of the natural copal, and turns into green, yellow-green and deep orange-yellow copal. It is very difficult to identify amber from the heat- pressurized treatment copal only based on the gemological parameters.The thermal behavior of amber and the copal before and after heat-pressurized treatment were analyzed by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance(NMR). The results show that amber exists an evident endothermic peak around 123~132°C, and copal reveals an obvious endothermic peak at about 174~178°C, and the heat pressurized treatment copal occurs a clear exothermic peak around 150~152°C. The differences between endothermic or exothermic transition and peak position reveal occurring thermal oxidation or the bond breaking or the melting, which are of great significance in the identification.

scholarly journals Influence of hydrotalcite preparation conditions on its physico-chemical properties

2019 ◽  
Vol 12 (1) ◽  
pp. 119-126
Author(s):  
Miroslava Mališová ◽  
Michal Horňáček ◽  
Pavol Hudec ◽  
Jozef Mikulec ◽  
Vladimír Jorík ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Chemical Properties ◽  
Synthesis Temperature ◽  
Optimal Synthesis ◽  
Preparation Process ◽  
Optimal Conditions ◽  
Temperature Range ◽  
Preparation Conditions ◽  
Physico Chemical ◽  
Ph Range

Abstract The aim of the research was to prepare and characterize hydrotalcite synthesized under different preparation conditions. The most common hydrotalcite preparation is the co-precipiaton method. The preparation process strongly influences the catalytic properties of hydrotalcite; therefore, optimal conditions have to be determined. During the study, seven samples of the catalyst were prepared in the pH range from 8 to 12 and the synthesis temperature range from 25 to 55 °C. Based on several catalyst properties, optimal synthesis pH 10 was found. Ideal temperature of the preparation was determined to be 35 °C, but the temperature does not have a significant effect on the catalyst properties.

scholarly journals Influence of the Calcination Temperature on the properties of The Alumina as Catalyst Support for Catalysis

Paliva ◽  
2020 ◽  
pp. 155-161
Author(s):  
Tomáš Hlinčík ◽  
Veronika Šnajdrová ◽  
Veronika Kyselová
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Catalyst Support ◽  
Chemical Properties ◽  
Total Pore Volume ◽  
Temperature Range ◽  
Calcination Temperatures ◽  
Physical And Chemical

Alumina is commonly used in industrial practice as a catalyst support and it is made from boehmite. Depending on the calcination temperature, this mineral is transformed into various crystalline modifications which have different physical and chemical properties. For this reason, the following parameters were determined at different calcination temperatures: length, width, material hardness, specific surface area and total pore volume. The results show that with increasing calcination temperature there have been significant changes which may be important when using the material as a catalyst support, e.g. in the preparation of catalysts or in the design of cat-alytic reactors. The specific surface area, which decreases in the temperature range 450–800 °C, is an important parameter for the preparation of catalysts, so it is appropriate to choose a temperature of 600 °C, when the specific surface area is above 200 m2·g-1. The effect of calcination temperature on the structural transitions of boehmite was also monitored. The results showed that γ-Al2O3 has the most suitable properties as a catalyst sup-port in the temperature range 450–800 °C.

New, Highly Structured Carbon Black of the OMCARB Series for Reducing the Hysteresis in Rubber. Part 1. Features of the Structure and Properties of Carbon Black

2016 ◽  
Vol 43 (12) ◽  
pp. 17-22
Author(s):  
G.V. Moiseevskaya ◽  
G.I. Razd'yakonova ◽  
A.A. Petin ◽  
E.A. Strizhak
Keyword(s):  
Carbon Black ◽  
Chemical Properties ◽  
Morphological Characteristics ◽  
Structural Data ◽  
Structure And Properties ◽  
Elastomeric Materials ◽  
Rubber Part ◽  
Average Size ◽  
Branched Structure ◽  
And Chemical Properties

The aim of this work was to study the properties of carbon black CH85 of the OMCARB series and to compare them with the properties of standard carbon blacks N339 and N234. The morphological characteristics, the size distribution of the globules and aggregates, the surface area, the proportion of micropore area, the degree of branching of aggregates, and also the mechanical and chemical properties were measured and calculated. The average size of the aggregates of CH85 is greater than that of N339 and N234, and the aggregates have a more open and branched structure. The iodine adsorption by CH85 is practically the same as that by N339 and lower than that by N234. The low-hysteresis index calculated on the basis of structural data is much better for CH85. This opens up the possibility of using this type of carbon black for the development of elastomeric materials with low hysteresis.

Fluorometric Analysis of Alkaline Phosphatase in Fluid Dairy Products

1990 ◽  
Vol 53 (7) ◽  
pp. 588-591 ◽  
Author(s):  
RICHARD M. ROCCO
Keyword(s):  
Alkaline Phosphatase ◽  
Dairy Products ◽  
Raw Milk ◽  
Test Sample ◽  
Reaction Rates ◽  
Product Formation ◽  
Test Time ◽  
Whole Milk ◽  
Repeated Analysis ◽  
Total Test Time

A new quantitative assay has been developed for measuring residual alkaline phosphatase (ALP) activity in a wide variety of dairy products including whole milk, low fat and skim milks, chocolate milk, and creams. ALP in the test sample hydrolyzes a nonfluorescent substrate, FluorophosR, to a highly fluorescent product. Product formation is monitored continuously during a short incubation period and enzyme activity is calculated from the rate of fluorescence increase. Total test time is 3 min. Reaction rates are linear up to 0.5% raw milk (equivalent to 5 μg phenol/ml/15 min) with a detection limit of 0.006% raw milk. Within and between run precision of the fluorometric method was assessed by repeated analysis of a pasteurized milk sample containing added mixed herd raw milk. The within run (N=10) mean was 190.4 mU/L, standard deviation (SD) 3.2, and a coefficient of variance (CV) of 1.7%. The procedure provides a rapid, sensitive, precise, and easy-to-use ALP assay, applicable to a wide variety of dairy products.

scholarly journals Synthesis and Characterization of Zirconium Nitride Nanopowders by Internal Gelation and Carbothermic Nitridation

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shijiao Zhao ◽  
Jingtao Ma ◽  
Rui Xu ◽  
Xuping Lin ◽  
Xing Cheng ◽  
...  
Keyword(s):  
Carbon Black ◽  
Chemical Properties ◽  
Phase Evolution ◽  
Zirconium Nitride ◽  
Molar Ratio ◽  
Nitridation Process ◽  
Zirconium Compounds ◽  
Physical And Chemical ◽  
And Chemical Properties

AbstractZirconium compounds has been widely attention over the last decades due to its excellent physical and chemical properties. Zirconium nitride nanopowders were synthesized via a simple direct carbothermic nitridation process of internal gel derived zirconia in the presence of nano-sized carbon black. The effects of reaction temperature, dwell time and molar ratio of carbon black to Zr (C/Zr) on the phase composition, grain size and crystal parameters of products were studied. Based upon the analysis of crystallite phase evolution and microstructure characterization, it was found that zirconium oxynitride is intermediate product and then O atoms in oxynitride were extracted by oxygen getter, carbon black. Anion sites were directly replaced by N atoms to form rock-salt type nitride in carbothermic nitridation process.

scholarly journals Revisiting nucleosynthesis in globular clusters

2017 ◽  
Vol 608 ◽  
pp. A28 ◽  
Author(s):  
N. Prantzos ◽  
C. Charbonnel ◽  
C. Iliadis
Keyword(s):  
Nuclear Reaction ◽  
Constant Temperature ◽  
Globular Clusters ◽  
Chemical Properties ◽  
Reaction Network ◽  
Stellar Populations ◽  
Reaction Rates ◽  
Temperature Range

Context. Motivated by recent reports concerning the observation of limited enrichment in He but excess K in stars of globular clusters, we revisit the H-burning conditions that lead to the chemical properties of multiple stellar populations in these systems. Aims. In particular, we are interested in correlations of He and K with other elements, such as O, Na, Al, Mg and Si, reported in stars of NGC 2808. Methods. We performed calculations of nucleosynthesis at constant temperature and density, exploring the temperature range of 25 to 200 × 106 K (25 to 200 MK), using a detailed nuclear reaction network and the most up-to-date nuclear reaction rates. Results. We find that Mg is the most sensitive “thermometer” of hydrostatic H-burning conditions, pointing to a temperature range of 70–80 MK for NGC 2808, while He is a lesser – but not negligible – constraint. Potassium can be produced at the levels reported for NGC 2808 at temperatures >180 MK and Si at T > 80 MK. However, in the former temperature range Al and Na are totally destroyed and no correlation can be obtained, in contrast to the reported observations. None of the putative polluter sources proposed so far seem to satisfy the ensemble of nucleosynthesis constraints.

The Action of Unsaturated Compounds on Natural Rubber in Solution. II. The Reaction Induced by Heat Alone

1952 ◽  
Vol 25 (2) ◽  
pp. 275-286
Author(s):  
André Delalande
Keyword(s):  
Free Radicals ◽  
Elevated Temperature ◽  
Natural Rubber ◽  
Addition Reaction ◽  
Thermal Reaction ◽  
Temperature Range ◽  
Unsaturated Compounds ◽  
Mechanism Of The Reaction

Abstract The addition reaction at an elevated temperature (170° C) of maleic N-methylimide with natural rubber in solution was studied. Attempts were made to apply the principles of kinetics to this thermal reaction with a view to understanding the nature of the reaction, but the complexity of the system made impossible any chance of attaining the results hoped for. A comparison of the fixation of acrylonitrile and that of maleic N-methylimide in the temperature range of 160°–200° C showed that the rates of these two reactions are in the ratio of 1 to 25–30. A determination of the unsaturation of the addition products showed that fixation is on the α-methylenic carbon atoms of the rubber hydrocarbon. Finally a mechanism of the reaction is proposed, in which free radicals play a part.

Mechanical Properties of WC-Co Cemented Carbide Prepared via Vacuum Sintering

2013 ◽  
Vol 275-277 ◽  
pp. 1917-1920
Author(s):  
Bing Liang Liang ◽  
Yun Long Ai ◽  
Chang Hong Liu ◽  
Nan Jiang
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Relative Density ◽  
Sintering Temperature ◽  
Rupture Strength ◽  
Cemented Carbide ◽  
Vacuum Sintering ◽  
Transverse Rupture Strength ◽  
Temperature Range ◽  
Peak Value

WC-Co cemented carbide specimens were prepared via vacuum sintering. The influences of composition and sintering temperature on phase composition, microstructure and mechanical properties of WC-Co cemented carbide were investigated. The results show that dense specimens were obtained in the sintering temperature range of 1280~1400°C and the relative density reached over 95%. Only WC and Co3W3C (-phase) were detected by XRD without any else phases, even though Co. With the ascended sintering temperature, hardness increased and the transverse rupture strength (TRS) ascended to peak value and then descended. WC-Co cemented carbide with excellent mechanical properties (HRA>90, TRS~700MPa and KIC>10MPa•m1/2) were obtained.

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