Strength Properties Of Elastomers At Low Temperatures

2011 ◽  
pp. 115-124
Keyword(s):  
Low Temperatures ◽  
Strength Properties

Polymeric Tribotechnical Composites on the Basis of Polytetrafluoroethylene and Complex Fillers

2020 ◽  
Vol 992 ◽  
pp. 733-738
Author(s):  
T.A. Isakova ◽  
P.N. Petrova
Keyword(s):  
Wear Resistance ◽  
Low Temperatures ◽  
High Performance ◽  
Polymeric Materials ◽  
Strength Properties ◽  
Planetary Mill ◽  
Magnesium Aluminate ◽  
Magnesium Aluminate Spinel ◽  
Initial Polymer ◽  
Properties Of Composites

Perspective polymeric materials for use in frictional units as bearings and sliding supports, the mobile sealants of piston rings, cuffs are composites on the basis of polytetrafluoroethylene (PTFE). They significantly improve the performance of equipment at low temperatures, reduce repair expenses and losses from idle times. When modifying polymers, physical methods of exposure are increasingly used, ensuring the activation of materials and high performance characteristics. Objective: the effect of complex fillers, obtained by their joint activation in a planetary mill, on the deformation and strength and tribological characteristics of composites based on PTFE. This work shows the promise of using the joint mechanical activation of components of different nature to obtain complex fillers. The use of the modified ultradispersed polytetrafluoroethylene (UPTFE) of zeolite as a filler of PTFE leads to complex improvement of properties of composites: the tensile strength and elongation at rupture increase by 20% in comparison with initial polymer. The wear resistance increases by 3-6 times in comparison with the composites containing only the activated zeolite and by 900 times in comparison with initial polymer. The addition of the modified UPTFE of a magnesium aluminate spinel (MAS) leads to increase in deformation and strength properties by 10-30% and an increase in wear resistance by 140 times in comparison with initial polymer.

Biodegradable Edible Film on the Basis of Apple Waste Products, i.e. Apple Marrow

Food Industry ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 32-43
Author(s):  
Nadezhda Makarova ◽  
Natalya Eremeeva ◽  
Yana Davydova
Keyword(s):  
Low Temperatures ◽  
Raw Materials ◽  
High Strength ◽  
Edible Films ◽  
Strength Properties ◽  
Film Structure ◽  
Apple Pomace ◽  
Edible Film ◽  
Plastic Properties ◽  
Waste Products

Edible film spread worldwide as an alternative to biodegradable polymer film can partially replace it as a packaging material for a number of food products. The article presents data on the study of samples of one-, two-, three-, four-, five-, six-, seven-, eight-, nine-, ten-layer edible films. Edible films are based on one of the most common types of fruit – apples. The film peculiarity is the Apple pomace introduction into its composition, which is currently not used enough in the food industry and is waste. The researchers studied: a) organoleptic properties (appearance, color, taste, aroma, chewability), surface microstructure of edible films using the laser microscopy; b) film structure by the IR spectroscopy; C) the ratio of the film to water, to the effects of high and low temperatures; d) strength properties. Research results show that the edible multi-layer film based on Apple raw materials with the addition of Apple pomace is quite suitable for organoleptic indicators for use. Despite the presence of individual cracks and voids in the film structure, it has high strength characteristics, is moderately resistant to water and low temperatures, but loses its plastic properties when MV-heating.

Accumulation and diffusion of charges in kinetics of polymer electric breakdown

2021 ◽  
Author(s):  
I. K. Aliyeva ◽  
T. M. Veliyev
Keyword(s):  
Activation Energy ◽  
Low Temperatures ◽  
Opposite Sign ◽  
Constant Electric Field ◽  
Strength Properties ◽  
Mean Value ◽  
Time Interval ◽  
Kinetics Of ◽  
And Diffusion ◽  
Mean Value Formula

In this paper, the distribution in electric durability [Formula: see text] of polymers in constant electric field at low temperatures has been measured. The results of continuous experiments and experiments of field discontinuous effect on polymer samples being remained not disruptive after exposure for time equal to mean value [Formula: see text] have been compared. During the interval, we have varied the time interval, temperature [Formula: see text] and electric intensity of opposite sign [Formula: see text] according to which various degree of regeneration of polymer electric strength properties has been observed. By the degree of regeneration, relaxation time [Formula: see text] of the accumulated charges in polymers causing breakdown has been found. It is established that the process of charge diffusion, which accumulation leads to breakdown has a thermofluctuation behavior and the activation energy of given process depends on the counter field intensity magnitude.

Low Temperature Joining of Copper by Ag Nanopaste: Studies on the Strength Behavior

2014 ◽  
Vol 925 ◽  
pp. 420-427 ◽  
Author(s):  
Susann Hausner ◽  
Sebastian Weis ◽  
Michael Elßner ◽  
Bernhard Wielage
Keyword(s):  
Thermal Properties ◽  
Low Temperatures ◽  
Base Material ◽  
Strength Properties ◽  
Scanning Calorimetry ◽  
Shape Distribution ◽  
Transmission Electron ◽  
Bulk Silver ◽  
Strength Behavior ◽  
Joining Strength

Nanoparticles exhibit a decrease in sintering and melting temperature with decreasing particle size. The utilization of this effect is of great interest for joining at low temperatures. First, the paper identifies possible applications for joining and their significance. Furthermore, a commercially available Ag nanopaste is characterized with respect to its thermal properties and strength behavior. Subsequently, it is qualified for joining at low temperatures. The shape, distribution and size of the nanoparticles are determined using transmission electron microscopy (TEM). The thermal behavior is characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG). Furthermore, first examinations of strength properties were executed for the base material copper in order to characterize the influence of different process parameters on joining strength. The analyses show that the nanopaste has a great potential for joining at low temperatures. It is verified that the organic shell of the nanoparticles oxidatively decomposes at temperatures of about 410 °C followed by a sintering process. The sintered microstructure exhibits the thermal properties of bulk silver. It is also shown, that it is possible to produce joints at even lower temperatures of about 300 °C, whose thermal resistance and joint strength is significantly superior to conventional soldered joints.

Influence of Phase Composition on Properties of Corundum-Zirconium Ceramic

2015 ◽  
Vol 756 ◽  
pp. 293-298
Author(s):  
Aleksander S. Ivashutenko ◽  
N.V. Martyushev ◽  
Valeriy P. Bezborodov
Keyword(s):  
Phase Composition ◽  
Low Temperatures ◽  
High Strength ◽  
Strength Properties ◽  
Zirconium Ceramic ◽  
Compressive Stresses ◽  
Metastable Condition

The results of the analysis of influence of the phase composition of corundum-zirconium ceramic on its properties are presented in this paper. It was established that the most perspective ceramic has composition 0,6 (ZrО2 + 3M% Y2O3) – 0,4 Аl2О3. High strength properties of this composition are determined by the presence of compressive stresses and the opportunity of retaining of tetragonal grains ZrО2 in a metastable condition at low temperatures.

SEM Study of Tension Wood Fiber Morphology and its Effect on Paper Properties

1977 ◽  
Vol 35 ◽  
pp. 308-309
Author(s):  
K. W. Robinson
Keyword(s):  
Tension Wood ◽  
Wood Fiber ◽  
Strength Properties ◽  
Fiber Morphology ◽  
Paper Properties ◽  
Pure Cellulose ◽  
Short Rotation ◽  
Hardwood Trees ◽  
Sem Study

Tension wood (TW) is an abnormal tissue of hardwood trees; although it has been isolated from most parts of the tree, it is frequently found on the upper side of branches and leaning stems. TW has been classically associated with geotropic alignment, but more recently it has been associated with fast growth. Paper made from TW is generally lower in strength properties. Consequently, the paper industries' growing dependence on fast growing, short- rotation trees will result in higher amounts of TW in the final product and a corresponding reduction in strength.Relatively few studies have dealt with the role of TW in the structure of paper. It was suggested that the lower strength properties of TW were due to a combination of factors, namely, its unique morphology, compression failures in the cell wall, and lower hemicellulose content. Central to the unique morphology of the TW fiber is the thick gelatinous layer (G-layer) composed almost entirely of pure cellulose.

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Radiation Damage of Support Films

1981 ◽  
Vol 39 ◽  
pp. 28-29
Author(s):  
H.A. Cohen ◽  
W. Chiu
Keyword(s):  
Transfer Function ◽  
Low Temperatures ◽  
Carbon Support ◽  
Contrast Transfer Function ◽  
Electron Dose ◽  
Imaging Parameters ◽  
Negative Stain ◽  
Phase Corrections ◽  
Two Parameters ◽  
Medium Dose

The goal of imaging the finest detail possible in biological specimens leads to contradictory requirements for the choice of an electron dose. The dose should be as low as possible to minimize object damage, yet as high as possible to optimize image statistics. For specimens that are protected by low temperatures or for which the low resolution associated with negative stain is acceptable, the first condition may be partially relaxed, allowing the use of (for example) 6 to 10 e/Å2. However, this medium dose is marginal for obtaining the contrast transfer function (CTF) of the microscope, which is necessary to allow phase corrections to the image. We have explored two parameters that affect the CTF under medium dose conditions.Figure 1 displays the CTF for carbon (C, row 1) and triafol plus carbon (T+C, row 2). For any column, the images to which the CTF correspond were from a carbon covered hole (C) and the adjacent triafol plus carbon support film (T+C), both recorded on the same micrograph; therefore the imaging parameters of defocus, illumination angle, and electron statistics were identical.

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