Spectral flux from low-density photospheres - Low-temperature results

1987 ◽  
Vol 322 ◽  
pp. 967 ◽  
Author(s):  
Stephen Hershkowitz ◽  
Robert V. Wagoner
Keyword(s):  
Low Temperature ◽  
Low Density ◽  
Spectral Flux

scholarly journals Low-Temperature Mechanical Properties of High-Density and Low-Density Polyethylene and Their Blends

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1821
Author(s):  
Ildar I. Salakhov ◽  
Nadim M. Shaidullin ◽  
Anatoly E. Chalykh ◽  
Mikhail A. Matsko ◽  
Alexey V. Shapagin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Impact Strength ◽  
Relative Elongation ◽  
High Density ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Elongation At Break ◽  
Subzero Temperatures ◽  
Izod Impact

Low-temperature properties of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and their blends were studied. The analyzed low-temperature mechanical properties involve the deformation resistance and impact strength characteristics. HDPE is a bimodal ethylene/1-hexene copolymer; LDPE is a branched ethylene homopolymer containing short-chain branches of different length; LLDPE is a binary ethylene/1-butene copolymer and an ethylene/1-butene/1-hexene terpolymer. The samples of copolymers and their blends were studied by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), 13С NMR spectroscopy, and dynamic mechanical analysis (DMA) using testing machines equipped with a cryochamber. It is proposed that such parameters as “relative elongation at break at −45 °C” and “Izod impact strength at −40 °C” are used instead of the ductile-to-brittle transition temperature to assess frost resistance properties because these parameters are more sensitive to deformation and impact at subzero temperatures for HDPE. LLDPE is shown to exhibit higher relative elongation at break at −45 °C and Izod impact strength at −20 ÷ 60 °C compared to those of LDPE. LLDPE terpolymer added to HDPE (at a content ≥ 25 wt.%) simultaneously increases flow properties and improves tensile properties of the blend at −45 °C. Changes in low-temperature properties as a function of molecular weight, MWD, crystallinity, and branch content were determined for HDPE, LLDPE, and their blends. The DMA data prove the resulting dependences. The reported findings allow one to understand and predict mechanical properties in the HDPE–LLDPE systems at subzero temperatures.

Molecule-Based Magnets—An Overview

MRS Bulletin ◽  
2000 ◽  
Vol 25 (11) ◽  
pp. 21-30 ◽  
Author(s):  
Joel S. Miller ◽  
Arthur J. Epstein
Keyword(s):  
Low Temperature ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Magnetic Ordering ◽  
Low Density ◽  
Materials Properties ◽  
The Common ◽  
New Processing ◽  
Very High

Molecule-based magnets are a broad, emerging class of magnetic materials that expand the materials properties typically associated with magnets to include low density, transparency, electrical insulation, and low-temperature fabrication, as well as combine magnetic ordering with other properties such as photoresponsiveness. Essentially all of the common magnetic phenomena associated with conventional transition-metal and rare-earth-based magnets can be found in molecule-based magnets. Although discovered less than two decades ago, magnets with ordering temperatures exceeding room temperature, very high (∼27.0 kOe or 2.16 MA/m) and very low (several Oe or less) coercivities, and substantial remanent and saturation magnetizations have been achieved. In addition, exotic phenomena including photoresponsiveness have been reported. The advent of molecule-based magnets offers new processing opportunities. For example, thin-film magnets can be prepared by means of low-temperature chemical vapor deposition and electrodeposition methods.

scholarly journals High Mechanic Enhancement of Chopped Carbon Fiber Reinforced-Low-Density Unsaturated Polyester Resin Composite at Low Preparation Temperature with Facile Polymerization

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4273
Author(s):  
Jian Zhang ◽  
Xiaojun Wang ◽  
Xinjun Fu
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Low Temperature ◽  
Surface Defect ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Unsaturated Polyester Resin ◽  
Low Density ◽  
Fiber Reinforced ◽  
Preparation Temperature

Chopped carbon fiber-reinforced low-density unsaturated polyester resin (CCFR-LDUPR) composite materials with light weight and high mechanical properties were prepared at low temperature and under the synergistic action of methyl ethyl ketone peroxide (MEKP-II) and cobalt naphthenate. Optimal preparation conditions were obtained through an orthogonal experiment, which were preparation temperature at 58.0 °C, 2.00 parts per hundred of resin (phr) of NH4HCO3, 4.00 phr of chopped carbon fibers (CCFs) in a length of 6.0 mm, 1.25 phr of initiator and 0.08 phr of cobalt naphthenate. CCFR-LDUPR composite sample presented its optimal properties for which the density (ρ) was 0.58 ± 0.02 g·cm−3 and the specific compressive strength (Ps) was 53.56 ± 0.83 MPa·g−1·cm3, which is 38.9% higher than that of chopped glass fiber-reinforced low-density unsaturated polyester resin (CGFR-LDUPR) composite materials. Synergistic effects of initiator and accelerator accelerated the specific polymerization of resin in facile preparation at low temperature. Unique “dimples”, “plate microstructure” and “surface defect” fabricated the specific microstructure of the matrix of CCFR-LDUPR composite samples, which was different from that of cured unsaturated polyester resin (UPR) with “body defect” or that of CGFR-LDUPR with coexistence of “surface defect” and “body defect”.

Direct Electron Heating Observed by Fast Waves in ICRF Range on a Low-Density Low Temperature Tokamak ADITYA

2011 ◽  
Author(s):  
K. Mishra ◽  
S. Kulkarni ◽  
D. Rathi ◽  
A. Varia ◽  
H. Jadav ◽  
...  
Keyword(s):  
Low Temperature ◽  
Low Density ◽  
Electron Heating ◽  
Fast Waves

Study on a New Cement for Deepwater Well Cementing

2012 ◽  
Vol 174-177 ◽  
pp. 1321-1325 ◽  
Author(s):  
Cheng Wen Wang ◽  
Zhi Gang Peng ◽  
Rui He Wang
Keyword(s):  
Low Temperature ◽  
Shallow Water ◽  
Gas Flow ◽  
Low Density ◽  
Test Results ◽  
Migration Control ◽  
Calcium Sulphoaluminate ◽  
Early Strength ◽  
Water Gas

In view of the new concerns in deepwater cementing, such as low temperature, shallow water/gas flow and so on, that can not be efficiently solved with conventional cement systems, a new SP-D cement with calcium sulphoaluminate and silicate was developed to adapt to deepwater low-temperature cementing. Test results show that the SP-D cement possesses high early-strength under low-temperature, favorable compatibility with conventional accelerators and retarders, and can be used to prepare the low density cement slurries combining with microsphere. The research offers a new SP-D cement for deepwater cementing with favorable high early-strength, improved migration control ability and minute expansion of set cement, and also shows prospective solution for the confronted problems in deepwater cementing.

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