Mechanical relaxation processes of wood in the low-temperature range

2001 ◽  
Vol 81 (13) ◽  
pp. 3338-3347 ◽  
Author(s):  
Eiichi Obataya ◽  
Misato Norimoto ◽  
Bunichiro Tomita
Keyword(s):  
Low Temperature ◽  
Mechanical Relaxation ◽  
Relaxation Processes ◽  
Temperature Range

scholarly journals New Insight into Dynamic Mechanical Relaxation in N-butyl-N-(2-nitroxy-ethyl) Nitramine Plasticized Nitrocellulose through Molecular Dynamic Simulations

2021 ◽  
Author(s):  
Xiaofei Qi ◽  
ning yan ◽  
Hongyan Li ◽  
Yu Zhao ◽  
Peijin Liu ◽  
...  
Keyword(s):  
Molecular Dynamic ◽  
Experimental Studies ◽  
Mechanical Analysis ◽  
Effect Of Temperature ◽  
Mechanical Relaxation ◽  
Relaxation Processes ◽  
Molecular Dynamic Simulations ◽  
Dynamic Simulations ◽  
Dynamic Mechanical ◽  
Temperature Range

Abstract We performed dynamic mechanical analysis (DMA) on nitrocellulose (NC) plasticized by an insensitive plasticizer N-butyl-N-(2-nitroxy-ethyl)nitramine (Bu-NENA). NC/Bu-NENA blend shows two mechanical relaxation processes in the temperature ranges of -50~-40oC and 30~40oC, and their variations with deformation frequencies were studied. To explore further the effect of temperature on relaxation, the binary mixture model of NC/Bu-NENA was constructed, and molecular dynamic simulations were conducted. The simulated mean square displacements (MSD) show abrupt increase in the temperature range of -50~-40oC and 30~40oC, which are consistent with those of the two relaxation processes observed in the DMA curves. Moreover, the free volume (Vfree) and torsion energy obtained from molecular dynamic simulations exhibit distinct increase at the temperature above 30oC and -50oC respectively, reflecting the sudden enhancements on the mobility of polymer chain elements and the rotation of molecular bonds. Furthermore, the radial distribution function (RDF) associated with the intermolecular interactions reveals that the intensities of both hydrogen bond and van-der-vaals forces decrease with the increase of temperature, which is responsible for the decrease of storage modulus at high temperature. These computational and experimental studies reveal guidance to strengthening the NC base propellants in broad temperature range.

Depolarization Thermocurrents in Ice Ih at Low Temperature

1981 ◽  
Vol 36 (4) ◽  
pp. 321-328 ◽  
Author(s):  
P. Pissis ◽  
G. Boudouris ◽  
J. C. Garson ◽  
J. L. Lévêque
Keyword(s):  
Low Temperature ◽  
Heating Rate ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Heating Rates ◽  
Temperature Range ◽  
Polycrystalline Ice

Polycrystalline ice samples frozen from highly purified water have been investigated by means of the depolarization thermo-current (DTC) technique in the temperature range 85-250 K. Three peaks have been observed at temperatures about 125, 165, and 225 K at a heating rate of 3.5 K/min. The measurements confirm most of the results reported by Johari and Jones. The characteristics of the low temperature DTC peak have been examined extensively for different samples, different heating rates and different polarization conditions. This peak has been found to be non-Debye. Its multiplicity has been studied experimentally using the possibilities offered by the DTC method. It may be better represented by a continuous ditribution of relaxation times than by a sum of discrete relaxation processes

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.

MAGNETIC PROPERTIES OF U1-xDyxAlyNi5-y (y=0,1) SYSTEMS

2003 ◽  
Vol 17 (27n28) ◽  
pp. 1453-1460
Author(s):  
ILEANA LUPSA
Keyword(s):  
Magnetic Properties ◽  
Low Temperature ◽  
Spin Fluctuation ◽  
Magnetic Moments ◽  
Transition Temperatures ◽  
Temperature Range ◽  
Fluctuation Model ◽  
Magnetically Ordered

The magnetic properties of U 1-x Dy x Al y Ni 5-y (y=0,1) systems were investigated in the 2(5)–600 K temperature range and for fields up to 80 kOe. The systems having x≥0.2 are magnetically ordered with low transition temperatures and magnetization mainly due to the Dy contribution. The nickel exhibits magnetic moments, very weak in the low temperature range and well-defined effective moments over transition temperatures. The nickel behavior is discussed in terms of the spin fluctuation model.

Hydrogen absorption in Ni-catalyzed Mg: A model for measurements in the low temperature range

2014 ◽  
Vol 39 (22) ◽  
pp. 11501-11508 ◽  
Author(s):  
Federico Cova ◽  
Fabiana Gennari ◽  
Pierre Arneodo Larochette
Keyword(s):  
Low Temperature ◽  
Hydrogen Absorption ◽  
Temperature Range

The low-temperature mechanical relaxation of elastin. I. The dry protein

Biopolymers ◽  
1976 ◽  
Vol 15 (2) ◽  
pp. 283-292 ◽  
Author(s):  
G. Pezzin ◽  
M. Scandola ◽  
L. Gotte
Keyword(s):  
Low Temperature ◽  
Mechanical Relaxation

LOW TEMPERATURE MODELS OF METAL OXIDE SEMICONDUCTOR FIELD-EFFECT TRANSISTORS

1995 ◽  
Vol 06 (02) ◽  
pp. 317-373 ◽  
Author(s):  
G. GILDENBLAT ◽  
D. FOTY
Keyword(s):  
Low Temperature ◽  
Field Effect Transistors ◽  
Numerical Models ◽  
Three Dimensional ◽  
Oxide Semiconductor ◽  
Characteristic Time Scale ◽  
Mos Transistors ◽  
Short Channel ◽  
Temperature Range ◽  
Dimensional Models

We review the modeling of silicon MOS devices in the 10–300 K temperature range with an emphasis on the specifics of low-temperature operation. Recently developed one-dimensional models of long-channel transistors are discussed in connection with experimental determination and verification of the effective channel mobility in a wide temperature range. We also present analytical pseudo-two-dimensional models of short-channel devices which have been proposed for potential use in circuit simulators. Several one-, two-, and three-dimensional numerical models are discussed in order to gain insight into the more subtle details of the low-temperature device physics of MOS transistors and capacitors. Particular attention is paid to freezeout effects which, depending on the device design and the ambient temperature range, may or may not be important for actual device operation. The numerical models are applied to study the characteristic time scale of freezeout transients in the space-charge regions of silicon devices, to the analysis and suppression of delayed turn-off in MOS transistors with compensated channel, and to the temperature dependence of three-dimensional effects in short-channel, narrow-channel MOSFETs.

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