Synthesis of AM-co-NVP and Thermal Stability in Hostile Saline Solution

2012 ◽  
Vol 602-604 ◽  
pp. 1349-1354 ◽  
Author(s):  
Rui Liu ◽  
Wan Fen Pu ◽  
Qin Peng ◽  
Feng Sheng Yao
Keyword(s):  
Thermal Stability ◽  
Saline Solution ◽  
Heat Stability ◽  
Structure Characterization ◽  
Vinyl Pyrrolidone ◽  
Molar Ratio ◽  
Mass Ratio ◽  
Excellent Thermal Stability ◽  
Hydrolyzed Polyacrylamide ◽  
Feed Molar Ratio

copolymer preparation; structure characterization; thermal stability; brines solution. Abstract. The copolymer (AM-co-NVP) of acrylamide (AM) and vinyl pyrrolidone (NVP) was carried out in the presence of 2,2'-azobis[2-methylpropionamidine] dihydrochloride（V50）as initiator by free radical polymerization. The copolymer was characterized by its chemical structure with Fourier transform infrared spectroscopy (FTIR). The heat resistance of AM-co-NVP at 100°C and 120°C in harsh saline solution with high mineralized concentration ranging from 5×104 mg/L to 20×104 mg/L containing 2.5% (mass ratio) CaCl2, 2.5% (mass ratio) MgCl2 and 95% NaCl (mass ratio) was investigated. The experimental results indicate that AM-co-NVP has excellent thermal stability in saline solution compared to partially hydrolyzed polyacrylamide (HPAM). What is more, the copolymer exhibited the most perfect thermal tolerance in high divalent saline solution when the feed molar ratio of AM and NVP is 91.5 to 8.5. The microstructures of the copolymer samples after thermal aging in hostile environment captured by scanning electron microscope (SEM）further proved the NVP monomer was effectively introduced leading to the copolymer favorable heat stability in particularly high mineralized solution.

Effect of preparation process on elevated temperature tribological properties of composite polyurea grease

2016 ◽  
Vol 68 (5) ◽  
pp. 611-616 ◽  
Author(s):  
Zujian Shen ◽  
Fei Geng ◽  
Xinxin Fan ◽  
Zhichen Shen ◽  
Haiyan Wang
Keyword(s):  
Thermal Stability ◽  
Elevated Temperature ◽  
Tribological Properties ◽  
Water Resistance ◽  
Physical Method ◽  
Heat Stability ◽  
Wear Properties ◽  
Excellent Thermal Stability ◽  
Content Type ◽  
Polyurea Grease

Purpose This paper aims to investigate and prepare the composite polyurea greases with excellent thermal stability and tribological properties. Design/methodology/approach In this paper, composite Ba-based (Ba, barium) tetra-polyurea lubricating greases were prepared with two different methods: mixing Ba-based gelatinizer and tetra-polyurea gelatinizer by a physical method; and introducing barium carboxylate into tetra-polyurea molecules by a chemical method. The properties of the products, such as heat stability, water resistance and friction performance, were analyzed with thermogravimetry, water-resistance test and four-ball friction test. Findings The results indicated that the products obtained by chemically introducing barium carboxylate into tetra-urea molecules showed better elevated temperature tribological properties, and the disadvantages of the polyurea greases with high temperature hardening were also obviously improved. The cone penetration rate at 180°C for 24 h is only 3 per cent. The friction coefficient can be decreased to 0.44 and the last non-seizure load value was increased from 560 N to 1,120 N without any other additives. Originality/value The research is significant because the prepared composite grease showed excellent performances, such as the outstanding thermal stability, water resistance and excellent extreme pressure and anti-wear properties, which may be widely applied in steel, metallurgy, bearings and other industrial fields.

Thermal Stability of Staphylococcal Enterotoxins A, B and C in a Buffered System

1987 ◽  
Vol 50 (3) ◽  
pp. 239-242 ◽  
Author(s):  
A. TIBANA ◽  
K. RAYMAN ◽  
M. AKHTAR ◽  
R. SZABO
Keyword(s):  
Thermal Stability ◽  
Heat Resistance ◽  
Saline Solution ◽  
Heat Stability ◽  
Staphylococcal Enterotoxins ◽  
Cooking Times ◽  
Phosphate Buffered Saline ◽  
Thermal Stability Of

The heat stability of staphylococcal enterotoxins A, B and C (SEA, SEB, SEC) in phosphate buffered saline solution at a concentration of 100 ng per ml indicated that normal cooking times and temperatures are unlikely to completely inactivate the toxins. The order of heat resistance of the three toxins was SEC>SEB>SEA.

High-Performance Copolymerized Poly(m-Phenylene Isophthalamide) (PMIA) Fibers Containing Ether Moiety: Preparation, Structure and Properties

2019 ◽  
Vol 960 ◽  
pp. 140-147
Author(s):  
Na Li ◽  
Xing Ke Zhang ◽  
Jun Rong Yu ◽  
Yan Wang ◽  
Jing Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Performance ◽  
Molar Ratio ◽  
Wet Spinning ◽  
Structure And Properties ◽  
Dye Uptake ◽  
Excellent Thermal Stability ◽  
Polycondensation Process ◽  
Solution Polycondensation

Copolymerized poly (m-phenylene isophthalamide) (co-PMIA) fibers with excellent thermal stability and good mechanical properties were developed via solution polycondensation process based on m-phenylenediamine (MPD), isophthaloyl dichloride (IPC), and 3,4′-oxydianiline (3,4′-ODA). Effects of the ether moiety on the structure and properties of the copolymers were investigated. A series of co-PMIA nascent fibers were produced using wet-spinning method. The coagulation process to form co-PMIA nascent fibers were studied by examination of SEM and strength tester. The co-PMIA nascent fibers with the MPD/3,4′-ODA molar ratio of 8:2 showed an optimum dye uptake. Keywords: Copolymerization; High performance material; Wet spinning; Dyeability.

scholarly journals Impact of Spherical Anatase TiO2 Nanoparticles on Thermal Properties of Polypropylene Resin

2021 ◽  
Author(s):  
Ahlem Bendaoued ◽  
Mouna Messaoud ◽  
Omar Harzallah ◽  
Sophie Bistac ◽  
Rached Salhi
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Sol Gel ◽  
Thermal Characterization ◽  
Degree Of Crystallinity ◽  
Molar Ratio ◽  
Excellent Thermal Stability ◽  
Energy Applications ◽  
Production Of Hydrogen ◽  
Thermal Stability Of

Abstract Ceramics nanometric reinforced polymer composite is a significant material for catalysis, solar cells, production of hydrogen and energy applications, etc. In order to take benefit from the interesting mechanical properties and thermal stability of TiO2, these ceramic nanomaterials was synthesized by the Sol-Gel process in attempt to study the thermal stability, structure, and morphology of the resulting nanoparticles powders. The obtained results revealed that, the sphere is composed of 20-30 nm nanoparticles with excellent thermal stability of nano-TiO2. This work focused on the thermal characterization and the study of nanocomposite xWt. %TiO2/PP (x=0, 2.5, 5, 7.5 mol%). In this study, the obtained results revealed that the molar ratio of TiO2 influences the final thermal stability and degree of crystallinity of the composite. It was found that the use of TiO2 seems to be an effective and very promising way to increase the thermal properties of the resulting composite. The greatest degree of crystallinity (54.80%) and thermal degradation stability are obtained for composite reinforced by 7.5Wt. %TiO2.

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

scholarly journals Boosted piezoelectricity with excellent thermal stability in tetragonal NaNbO3-based ceramics

2020 ◽  
Author(s):  
Lu Wang ◽  
Shengdong Sun ◽  
Huajie Luo ◽  
Yang Ren ◽  
Hui Liu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Temperature Stability ◽  
Lead Free ◽  
Excellent Thermal Stability ◽  
Lead Free Ceramics ◽  
Piezoelectric Performance

The realization of high piezoelectric performance and excellent temperature stability simultaneously in lead-free ceramics is the key for replacing Pb-containing perovskites in industry. In this study, large piezoelectric performance (d33...

scholarly journals Continuous Integrated Process of Biodiesel Production and Purification—The End of the Conventional Two-Stage Batch Process?

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 403
Author(s):  
Matea Bačić ◽  
Anabela Ljubić ◽  
Martin Gojun ◽  
Anita Šalić ◽  
Ana Jurinjak Tušek ◽  
...  
Keyword(s):  
Extraction Efficiency ◽  
Deep Eutectic Solvent ◽  
International Standards ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Process Conditions ◽  
Integrated Process ◽  
Free Glycerol ◽  
Mass Ratio ◽  
Glycerol Content

In this research, optimization of the integrated biodiesel production process composed of transesterification of edible sunflower oil, catalyzed by commercial lipase, with simultaneous extraction of glycerol from the reaction mixture was performed. Deep eutectic solvents (DESs) were used in this integrated process as the reaction and extraction media. For two systems, choline chloride:glycerol (ChCl:Gly) and choline chloride:ethylene glycol (ChCl:EG), respectively, the optimal water content, mass ratio of the phase containing the mixture of reactants (oil and methanol) with an enzyme and a DES phase (mass ratio of phases), and the molar ratio of deep eutectic solvent constituents were determined using response surface methodology (RSM). Experiments performed with ChCl:Gly resulted in a higher biodiesel yield and higher glycerol extraction efficiency, namely, a mass ratio of phases of 1:1, a mass fraction of water of 6.6%, and a molar ratio of the ChCl:Gly of 1:3.5 were determined to be the optimal process conditions. When the reaction was performed in a batch reactor under the optimal conditions, the process resulted in a 43.54 ± 0.2% yield and 99.54 ± 0.19% glycerol extraction efficiency (t = 2 h). Unfortunately, the free glycerol content was higher than the one defined by international standards (wG > 0.02%); therefore, the process was performed in a microsystem to enhance the mass transfer. Gaining the same yield and free glycerol content below the standards (wG = 0.0019 ± 0.003%), the microsystem proved to be a good direction for future process optimization.

scholarly journals Preparation and Thermal Conductivity of Epoxy Resin/Graphene-Fe3O4 Composites

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2013
Author(s):  
Zhong Wu ◽  
Jingyun Chen ◽  
Qifeng Li ◽  
Da-Hai Xia ◽  
Yida Deng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Thermal Stability ◽  
Epoxy Resin ◽  
Thermomechanical Properties ◽  
Packaging Materials ◽  
Mass Ratio ◽  
Degree Of Orientation ◽  
Ep Matrix ◽  
Electrical Insulation Properties

By modifying the bonding of graphene (GR) and Fe3O4, a stable structure of GR-Fe3O4, namely magnetic GR, was obtained. Under the induction of a magnetic field, it can be orientated in an epoxy resin (EP) matrix, thus preparing EP/GR-Fe3O4 composites. The effects of the content of GR and the degree of orientation on the thermal conductivity of the composites were investigated, and the most suitable Fe3O4 load on GR was obtained. When the mass ratio of GR and Fe3O4 was 2:1, the thermal conductivity could be increased by 54.8% compared with that of pure EP. Meanwhile, EP/GR-Fe3O4 composites had a better thermal stability, dynamic thermomechanical properties, and excellent electrical insulation properties, which can meet the requirements of electronic packaging materials.

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