Distinct kinetics of molecular gelation in a confined space and its relation to the structure and property of thin gel films

2015 ◽  
Vol 17 (12) ◽  
pp. 8258-8265 ◽  
Author(s):  
Yu Liu ◽  
Wen-Jing Zhao ◽  
Jing-Liang Li ◽  
Rong-Yao Wang
Keyword(s):  
Mechanical Properties ◽  
Network Structure ◽  
Confined Space ◽  
Kinetic Feature ◽  
Fiber Network ◽  
Structure And Property ◽  
Kinetics Of

Distinct kinetic feature of the molecular gelation in a confined or unconfined regime, and its relationship with the tailored fiber network structure and mechanical properties.

scholarly journals Fibrin network structure and clot mechanical properties are altered by incorporation of erythrocytes

2009 ◽  
Vol 102 (12) ◽  
pp. 1169-1175 ◽  
Author(s):  
Kathryn Gersh ◽  
Chandrasekaran Nagaswami ◽  
John Weisel
Keyword(s):  
Mechanical Properties ◽  
Network Structure ◽  
Fibrin Clot ◽  
Scanning Electron Micrographs ◽  
Fiber Network ◽  
Fibrin Network ◽  
Clot Structure ◽  
Fibrin Network Structure

SummaryAlthough many in vitro fibrin studies are performed with plasma, in vivo clots and thrombi contain erythrocytes, or red blood cells (RBCs).To determine the effects of RBCs on fibrin clot structure and mechanical properties, we compared plasma clots without RBCs to those prepared with low (2 vol%), intermediate (5-10 vol%), or high (≥20 vol%) numbers of RBCs. By confocal microscopy, we found that low RBC concentrations had little effect on clot structure. Intermediate RBC concentrations caused heterogeneity in the fiber network with pockets of densely packed fibers alongside regions with few fibers. With high levels of RBCs, fibers arranged more uniformly but loosely around the cells. Scanning electron micrographs demonstrated an uneven distribution of RBCs throughout the clot and a significant increase in fiber diameter upon RBC incorporation. While permeability was not affected by RBC addition, at 20% or higher RBCs, the ratio of viscous modulus (G′′) to elastic modulus (G′) increased significantly over that of a clot without any RBCs. RBCs triggered variability in the fibrin network structure, individual fiber characteristics, and overall clot viscoelasticity compared to the absence of cells. These results are important for understanding in vivo clots and thrombi.

Elaboration and Characterization of the Properties of Refractory Cr Base Alloys

2010 ◽  
Vol 72 ◽  
pp. 46-52 ◽  
Author(s):  
Laurent Royer ◽  
Stéphane Mathieu ◽  
Christophe Liebaut ◽  
Pierre Steinmetz
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Molten Glass ◽  
Energy Production ◽  
Creep Properties ◽  
Refractory Alloys ◽  
Industrial Use ◽  
Kinetics Of ◽  
Selection Of

For energy production and also for the glass industry, finding new refractory alloys which could permit to increase the process temperatures to 1200°C or more is a permanent challenge. Chromium base alloys can be good candidates, considering the melting point of Cr itself, and also its low corrosion rate in molten glass. Two families of alloys have been studied for this purpose, Cr-Mo-W and Cr-Ta-X alloys (X= Mo, Si..). A finer selection of compositions has been done, to optimize their chemical and mechanical properties. Kinetics of HT oxidation by air, of corrosion by molten glass and also creep properties of several alloys have been measured up to 1250°C. The results obtained with the best alloys (Cr-Ta base) give positive indications as regards the possibility of their industrial use.

Tailoring martensitic transformation and mechanical properties of Ti–Ni composite reinforced by network structure of in-situ TiB and La2O3 phase

Vacuum ◽  
2021 ◽  
Vol 184 ◽  
pp. 109894 ◽  
Author(s):  
Xiaoyang Yi ◽  
Haizhen Wang ◽  
Kuishan Sun ◽  
Guijuan Shen ◽  
Xianglong Meng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Martensitic Transformation ◽  
Network Structure

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

Effect of Minor Additives on First Stage Graphitisation in White Cast Iron

1984 ◽  
Vol 34 ◽  
Author(s):  
P. L. Roy ◽  
A. K. Chakrabart ◽  
P. Banerjee
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Sodium Chloride ◽  
Yield Strength ◽  
White Cast Iron ◽  
Elemental Sulphur ◽  
Optimum Dose ◽  
White Iron ◽  
Kinetics Of ◽  
Strength And Ductility

ABSTRACTMinor additions (0.05-0.2 wt.%) of sodium chloride, hexachloroethane and elemental sulphur to commercial white iron melts have been found to enhance the kinetics of first stage graphitisation during subsequent annealing of white iron samples. The optimum dose of sodium chloride and hexachloroethane addition is around 0.1%. Yield strength and ductility of annealed test bars treated with NaCl or C2Cl6 compare favourably with those of untreated test bars. Sulphur treatment causes slight deterioration in mechanical properties. Fully grown nodules in both treated and untreated samples appear porous under SEM. Possible mechanisms of acceleration of graphitisation in the treated samples have been suggested.

Micro-Pore Structure and Mechanical Properties of High Temperature Self-Lubricating Biomimetic TiC/FeCrWMoV Cermets

2007 ◽  
Vol 546-549 ◽  
pp. 2273-2278 ◽  
Author(s):  
Yan Jun Wang ◽  
Zuo Min Liu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Powder Metallurgy ◽  
Pore Structure ◽  
Network Structure ◽  
Sweat Gland ◽  
Solid Lubricant ◽  
Rayleigh Distribution

A new cermet sinter with sweat-gland micro-pore structure has been developed by powder metallurgy technology in vacuum. The effects of the pore-forming materials on micro-pore structure and Y2O3 additions as well mechanical properties of TiC/FeCrWMoV cermets were investigated. Some typical sweat-gland micro-pores were formed while compound additives TiH2 and CaCO3 adding into the sinter matrix. The porosity of the cermet sinters changes from 20% to 28% with the compound additives from 6% to 8%, and the micro-pores of sinters exist a regularized and interpenetrated network structure just like human’s sweat-gland one and obeying to Rayleigh Distribution. As such the sinters could be easily infiltrated with high-temperature solid lubricant. For improving the property of the ceramet sinter, the elements Y2O3 of 0.6～0.8% (vol. fraction ) was also added into the sinter matrix and its effect on the sinter has been also discussed .

Influence of High-Calcium Ash Composition on the Composite Binders’ Properties

2021 ◽  
Vol 316 ◽  
pp. 1019-1024
Author(s):  
O. A. Ignatova ◽  
A. A. Dyatchina
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Cement Stone ◽  
Normal Density ◽  
Fine Aggregate ◽  
Equivalent Amount ◽  
High Calcium ◽  
Composition Structure ◽  
Kinetics Of ◽  
Positive Effect

The paper presents the studies’ results of chemical composition, structure, and physico-mechanical properties of high-calcium ashes from the Kansk-Achinsk coals (2017-2019 selection). It was found that ash has a complex poly-mineral composition and contains hydraulically active minerals and oxides of СаОfr, β-C2S, CA, C3A, C4AF, C2F, CaSO4. According to the content of CaOfr, MgO does not meet standards’ requirements. The uniformity of the volume change is maintained by the composition with 50% of cement. The structure and hardening kinetics of ash and ash-cement stone compositions, obtained from the test of normal density, were analyzed. It was established that the hardening of compositions with ash from the Kansk-Achinsk coals was largely influenced by ash minerals. An equivalent amount of cement in composite binders cannot be replaced. In order to obtain a positive effect, compositions with ash instead cement of no more than 30% and a part of fine aggregate, without exceeding the ratio of ash: cement = 1: 1, should be used.

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