Rheology and Microstructure of Polymer/Asphalt Blends

1991 ◽  
Vol 64 (4) ◽  
pp. 577-600 ◽  
Author(s):  
M. G. Bouldin ◽  
J. H. Collins ◽  
A. Berker
Keyword(s):  
High Temperature ◽  
Low Temperatures ◽  
Elevated Temperatures ◽  
Polymer Concentration ◽  
Deformation Energy ◽  
Plateau Modulus ◽  
Temperature Range ◽  
Low Viscosity ◽  
Mechanical Measurements ◽  
Polymer Type

Abstract This work demonstrates the effectiveness of polymers in improving, especially, the high temperature properties of asphalt. The appropriate choice of asphalt, asphalt-grade, polymer type, polymer concentration, and the method of mixing determine if a network-like structure is formed. This morphology significantly improves the creep performance of the binder at elevated temperatures, i.e., the binder has the ability to store deformation energy with subsequent recoil. This is contrary to Newtonian fluids which transform the energy into viscous flow (no recoil). Within the context of dynamic mechanical measurements, the presence of a polymeric network is manifested through the appearance of a plateau modulus. In the case of binders containing block copolymers, we have repeatedly observed that such property improvement in the high-temperature range is generally accompanied by a reduction of the glassy modulus at the low-temperature range as well. It should be noted that by modifying low-viscosity asphalts (i.e., low AC-grades) with polymers, binders can be obtained which exhibit significantly lower moduli at low temperatures and higher moduli at elevated temperatures. This suggests that although using a high AC-grade asphalt may yield satisfactory results at a particular temperature (high temperature), one may instead optimize binders over the entire temperature range (high and low) by starting with a low AC-grade and adding polymer. These results indicate that careful Theological measurements can be a powerful tool in the characterization and design of viscoelastic blends.

CMOS Circuits on Silicon Carbide for High Temperature Operation

2014 ◽  
Vol 1693 ◽  
Author(s):  
David T. Clark ◽  
Robin F. Thompson ◽  
Aled E. Murphy ◽  
David A. Smith ◽  
Ewan P. Ramsay ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Wide Temperature Range ◽  
Integrated Circuit ◽  
Elevated Temperatures ◽  
Logic Circuits ◽  
Digital Logic ◽  
Cmos Integrated Circuit ◽  
Temperature Range ◽  
Simple Logic

ABSTRACTWe present the characteristics of a high temperature CMOS integrated circuit process based on 4H silicon carbide designed to operate at temperatures beyond 300°C. N-channel and P-channel transistor characteristics at room and elevated temperatures are presented. Both channel types show the expected low values of field effect mobility well known in SiC MOSFETS. However the performance achieved is easily capable of exploitation in CMOS digital logic circuits and certain analogue circuits, over a wide temperature range.Data is also presented for the performance of digital logic demonstrator circuits, in particular a 4 to 1 analogue multiplexer and a configurable timer operating over a wide temperature range. Devices are packaged in high temperature ceramic dual in line (DIL) packages, which are capable of greater than 300°C operation. A high temperature “micro-oven” system has been designed and built to enable testing and stressing of units assembled in these package types. This system heats a group of devices together to temperatures of up to 300°C while keeping the electrical connections at much lower temperatures. In addition, long term reliability data for some structures such as contact chains to n-type and p-type SiC and simple logic circuits is summarized.

scholarly journals On the applicability of the equipartition theorem

2010 ◽  
Vol 14 (3) ◽  
pp. 855-858 ◽  
Author(s):  
Edward Bormashenko ◽  
Oleg Gendelman
Keyword(s):  
High Temperature ◽  
Low Temperatures ◽  
Standard Form ◽  
Temperature Limit ◽  
Large Displacements ◽  
Temperature Range ◽  
High Temperature Limit ◽  
Equipartition Theorem ◽  
Equipartition Of Energy

Generalization of the equipartition theorem is presented for a broad range of potentials U(x) with quadratic minimum. It is shown, that the equipartition of energy in its standard form appears at the low temperatures limit. For potentials demonstrating the quadratic behavior for large displacements from the equilibrium the equipartition holds also in the high temperature limit. The temperature range of applicability of the equipartition theorem for the potential U = ax2 + bx4 was established.

Thermally Stimulated Conductivity in a-Si:H at low Temperatures

1994 ◽  
Vol 336 ◽  
Author(s):  
M. Zhu ◽  
M.B. Von Der Linden ◽  
W.F. Van Der Weg
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Thermal Emission ◽  
Temperature Peak ◽  
Band Tail ◽  
Emission Energy ◽  
Temperature Range ◽  
Multiple Trapping ◽  
Peak Value

ABSTRACTThe low temperature thermally stimulated conductivity (TSC) in a-Si:H film has been investigated in the temperature range from 20 to 150 K. Unlike the results of the high temperature TSC, the low temperature peak value and position (Tm) of TSC do not depend on the starting temperature T0 at low temperatures. This new phenomenon can not be explained by TSC theory [1]. Based on the multiple trapping (MT) Model, TSC theory limits its application to the intermediate and high temperature range. In this paper, a model of the hopping conduction with the transport energy Et in the band tail is proposed to understand the behavior of the low temperature TSC in which the thermal emission energy Em does not depend on the starting temperature of TSC.

Mechanical and Fracture Behaviour of a SiC-Particle-Reinforced Aluminum Alloy at High Temperature

2005 ◽  
Vol 494 ◽  
pp. 487-492 ◽  
Author(s):  
D. Božić ◽  
M. Vilotijević ◽  
V. Rajković ◽  
Ž. Gnjidić
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Compressive Loading ◽  
Constant Strain Rate ◽  
High Concentration ◽  
Monolithic Alloy ◽  
Temperature Range ◽  
Hardened Alloy

The compressive characteristics and fracture behavior of CW67 aluminum alloy and of a composite based on CW67 alloy were studied under unaxial compressive loading in the temperature range 25-400°C, at a constant strain rate of 1 - 3 10 4 . 2 s × . The yield strength values of the composite were higher than those of the monolithic alloy at all temperatures. The ultimate strength values of the composite were lower at room temperature, but higher at elevated temperatures when compared with those of the monolithic alloy. The composite exhibited lower ductility than the monolithic alloy in the entire temperature range. High concentration of SiC particles in the structure of CW67 composite affected its compressive properties. At higher temperatures, it behaved like a typical precipitation hardened alloy, in other words, with temperature increase the main influence on the mechanical properties occurred in its matrix. When temperature rises, the fracture process changes from particle cracking and particle agglomerate decohesion (at room temperature) to particle matrix debonding (at high temperature).

Features of the Reinforcing Action of Carbon Blacks Deduced from the Tear Propagation of Filled Vulcanizates

1961 ◽  
Vol 34 (1) ◽  
pp. 57-65
Author(s):  
A. I. Lukomskaya
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Stress Distribution ◽  
Carbon Black ◽  
Natural Rubber ◽  
High Temperatures ◽  
Low Temperatures ◽  
Temperature Range ◽  
Carbon Blacks ◽  
Tear Propagation

Abstract 1. The reinforcing action of carbon blacks is most clearly apparent in the knotty tearing of carbon black rubbers. 2. Knotty tearing is characteristic of rubbers filled with carbon black in definite ranges of deformation and temperature, the position of which depends upon the type of rubber and carbon black. 3. With high contents of contact gas black in vulcanizates of sodium butadiene (SKB) and butadiene sytrene (SKS-30) rubbers two ranges of knotty tearing occur. The first is situated at relatively high temperatures and low rates and the second at relatively low temperatures and higher rates. Reduction in the content of black in these vulcanizates leads to the disappearance of the high temperature range of knotty tearing and the displacement of the low-temperature range towards higher temperatures and low rates. This position of the ranges (at medium rates and temperatures) is characteristic also of the said synthetic rubbers containing thermal black. 4. The first range of knotty tearing of filled SKB and SKS-30 vulcanizates with contact black is linked with the presence in them of carbon black chains, while the second range, existing also with vulcanizates with thermal black, is connected with the presence of carbon black particles. 5. Within the ranges ofr ates from 40 to 1000 mm/min and of temperatures from 40 to +100° C filled vulcanizates of natural rubber have one range of knotty tearing situated at lower rates. In the case of the presence in them of contact gas black the range is shifted towards higher rates than in the case of thermal black. 6. Increasing the length of the nick in testpieces being tested for tear propagation leads to a shift in the range of knotty tearing towards higher rates and widens it with respect to temperatures. This same effect is noted on altering the shape of the testpiece, starting with the Delft testpieces and proceeding to types A, B, and C, i.e. increasing the nonuniformity of stress distribution in the deformed testpieces.

High-Temperature Instability of A Cr2Nb-Nb(Cr) Microlaminate Composite

1996 ◽  
Vol 54 ◽  
pp. 374-375
Author(s):  
M. Larsen ◽  
R.G. Rowe ◽  
D.W. Skelly
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Aircraft Engine ◽  
Lattice Parameter ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Cross Sectional ◽  
Bcc Structure

Microlaminate composites consisting of alternating layers of a high temperature intermetallic compound for elevated temperature strength and a ductile refractory metal for toughening may have uses in aircraft engine turbines. Microstructural stability at elevated temperatures is a crucial requirement for these composites. A microlaminate composite consisting of alternating layers of Cr2Nb and Nb(Cr) was produced by vapor phase deposition. The stability of the layers at elevated temperatures was investigated by cross-sectional TEM.The as-deposited composite consists of layers of a Nb(Cr) solid solution with a composition in atomic percent of 91% Nb and 9% Cr. It has a bcc structure with highly elongated grains. Alternating with this Nb(Cr) layer is the Cr2Nb layer. However, this layer has deposited as a fine grain Cr(Nb) solid solution with a metastable bcc structure and a lattice parameter about half way between that of pure Nb and pure Cr. The atomic composition of this layer is 60% Cr and 40% Nb. The interface between the layers in the as-deposited condition appears very flat (figure 1). After a two hour, 1200 °C heat treatment, the metastable Cr(Nb) layer transforms to the Cr2Nb phase with the C15 cubic structure. Grain coarsening occurs in the Nb(Cr) layer and the interface between the layers roughen. The roughening of the interface is a prelude to an instability of the interface at higher heat treatment temperatures with perturbations of the Cr2Nb grains penetrating into the Nb(Cr) layer.

Phase transformation and layer evolution in molybdenum disilicide-silicon carbide nanolayered coatings

1994 ◽  
Vol 52 ◽  
pp. 538-539
Author(s):  
H. Kung ◽  
T. R. Jervis ◽  
J.-P. Hirvonen ◽  
M. Nastasi ◽  
T. E. Mitchell ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Oxidation Resistance ◽  
Elevated Temperatures ◽  
Matrix Material ◽  
Molybdenum Disilicide ◽  
High Temperature Strength ◽  
Cross Sectional ◽  
Good Oxidation Resistance ◽  
Structural Applications

MoSi2 is a potential matrix material for high temperature structural composites due to its high melting temperature and good oxidation resistance at elevated temperatures. The two major drawbacksfor structural applications are inadequate high temperature strength and poor low temperature ductility. The search for appropriate composite additions has been the focus of extensive investigations in recent years. The addition of SiC in a nanolayered configuration was shown to exhibit superior oxidation resistance and significant hardness increase through annealing at 500°C. One potential application of MoSi2- SiC multilayers is for high temperature coatings, where structural stability ofthe layering is of major concern. In this study, we have systematically investigated both the evolution of phases and the stability of layers by varying the heat treating conditions.Alternating layers of MoSi2 and SiC were synthesized by DC-magnetron and rf-diode sputtering respectively. Cross-sectional transmission electron microscopy (XTEM) was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures.

The reaction of amorphous Ni-Nb films with Si in the presence of a native SiO2 layer

1990 ◽  
Vol 48 (4) ◽  
pp. 664-665
Author(s):  
N. Rozhanski ◽  
A. Barg
Keyword(s):  
High Temperature ◽  
Crystallization Temperature ◽  
Diffusion Barriers ◽  
Sio2 Layer ◽  
Si Substrate ◽  
Cross Sectional ◽  
Plan View ◽  
Temperature Range ◽  
Sputter Deposited

Amorphous Ni-Nb alloys are of potential interest as diffusion barriers for high temperature metallization for VLSI. In the present work amorphous Ni-Nb films were sputter deposited on Si(100) and their interaction with a substrate was studied in the temperature range (200-700)°C. The crystallization of films was observed on the plan-view specimens heated in-situ in Philips-400ST microscope. Cross-sectional objects were prepared to study the structure of interfaces.The crystallization temperature of Ni5 0 Ni5 0 and Ni8 0 Nb2 0 films was found to be equal to 675°C and 525°C correspondingly. The crystallization of Ni5 0 Ni5 0 films is followed by the formation of Ni6Nb7 and Ni3Nb nucleus. Ni8 0Nb2 0 films crystallise with the formation of Ni and Ni3Nb crystals. No interaction of both films with Si substrate was observed on plan-view specimens up to 700°C, that is due to the barrier action of the native SiO2 layer.

Features of radiothermoluminescence of polypropylene and ethylene propylenediene elastomer SKEPT-4044 compositions with nanoscale metal-containing fillers

2020 ◽  
pp. 66-73
Author(s):  
A.M. Magerramov ◽  
◽  
N.I. Kurbanova ◽  
M.N. Bayramov ◽  
N.A. Alimirzoyeva ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Molecular Mobility ◽  
Fe3o4 Nanoparticles ◽  
Low Temperatures ◽  
Frost Resistance ◽  
Relaxation Processes ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Β Relaxation

Using radiothermoluminescence (RTL), the molecular mobility features in the temperature range of 77-300 K were studied for the polypropylene (PP)/ethylene propylene diene elastomer SKEPT-4044 with NiO, Cu2O and Fe3O4 nanoparticles (NPs) based on ABS-acrylonitrile butadiene or SCS-divinyl styrene matrices. It has been shown that the introduction of nanofillers in PP significantly affects the nature and temperature of γ- and β-relaxation processes, while the region of manifestation of the β-process noticeably shifts to the region of low temperatures. Composites with Cu2O NPs have a higher β-transition temperature Tβ than composites with other NPs. It was found that PP/SKEPT-4044 composites with Cu2O NPs with a dispersion of 11-15 nm and acrylonitrile butadiene thermoplastics have optimal frost resistance compared to other compositions.

WIELAND-K88

Alloy Digest ◽  
2005 ◽  
Vol 54 (12) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Stress Relaxation ◽  
Copper Alloy ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Relaxation Resistance ◽  
Temperature Performance ◽  
Very High

Abstract Wieland K-88 is a copper alloy with very high electrical and thermal conductivity, good strength, and excellent stress relaxation resistance at elevated temperatures. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: CU-738. Producer or source: Wieland Metals Inc.

Sign in / Sign up

Export Citation Format

Share Document