Isotopic equilibrium constants for very low-density and low-temperature nuclear matter

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.

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Molecule-Based Magnets—An Overview

MRS Bulletin ◽

10.1557/mrs2000.221 ◽

2000 ◽

Vol 25 (11) ◽

pp. 21-30 ◽

Cited By ~ 115

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.

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

Materials ◽

10.3390/ma14154273 ◽

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”.

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The experimental determination of hydromagnesite precipitation rates at 22.5–75ºC

Mineralogical Magazine ◽

10.1180/minmag.2014.078.6.07 ◽

2014 ◽

Vol 78 (6) ◽

pp. 1405-1416 ◽

Cited By ~ 11

Author(s):

U.-N. Berninger ◽

G. Jordan ◽

J. Schott ◽

E. H. Oelkers

Keyword(s):

Low Temperature ◽

Experimental Determination ◽

Closed System ◽

Equilibrium Constants ◽

Magnesium Silicate ◽

Silicate Mineral ◽

Dissolution Rates ◽

Dissolution And Precipitation

Natural hydromagnesite (Mg5(CO3)4(OH)2·4H2O) dissolution and precipitation experiments were performed in closed-system reactors as a function of temperature from 22.5 to 75ºC and at 8.6 < pH < 10.7. The equilibrium constants for the reaction Mg5(CO3)4(OH)2·4H2O + 6H+ = 5Mg2+ + 4HCO3– + 6H2O were determined by bracketing the final fluid compositions obtained from the dissolution and precipitation experiments. The resulting constants were found to be 1033.7±0.9, 1030.5±0.5 and 1026.5±0.5 at 22.5, 50 and 75ºC, respectively. Whereas dissolution rates were too fast to be determined from the experiments, precipitation rates were slower and quantified. The resulting BET surface areanormalized hydromagnesite precipitation rates increase by a factor of ~2 with pH decreasing from 10.7 to 8.6. Measured rates are approximately two orders of magnitude faster than corresponding forsterite dissolution rates, suggesting that the overall rates of the low-temperature carbonation of olivine are controlled by the relatively sluggish dissolution of the magnesium silicate mineral.

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Alpha-Clustering in Nuclear Matter at Low Density

Progress of Theoretical Physics ◽

10.1143/ptp.29.933 ◽

1963 ◽

Vol 29 (6) ◽

pp. 933-935 ◽

Cited By ~ 9

Author(s):

Minoru Harada ◽

Ryozo Tamagaki ◽

Hajime Tanaka

Keyword(s):

Nuclear Matter ◽

Low Density ◽

Alpha Clustering

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Enhanced Oxidation of Air Contaminants on an Ultra-Low Density UV-Accessible Aerogel Photocatalyst

MRS Proceedings ◽

10.1557/proc-454-141 ◽

1996 ◽

Vol 454 ◽

Cited By ~ 3

Author(s):

M. Dreyer ◽

G. K. Newman ◽

L. Lobban ◽

S. J. Kersey ◽

R. Wang ◽

...

Keyword(s):

Reaction Rate ◽

Adsorption Equilibrium ◽

Uv Light ◽

Equilibrium Constants ◽

Main Stream ◽

Low Density ◽

Air Contaminants ◽

Reaction Rate Constants ◽

Air Contaminant ◽

Type Rate

ABSTRACTThis research developed new forms of photocatalysts that could potentially move photocatalytic degradation of air contaminants into the main stream of industrially used remediation technologies. Tests of the photocatalytic activity of the TiO2 aerogel catalysts have been carried out using both acetone and methane as the air contaminant. For comparison, the same tests were carried out on a standard (non-aerogel) anatase powder. Despite having very low crystallinity, the aerogel decontaminates the air far more effectively than an equal volume of the anatase powder which indicates that a much larger fraction of the aerogel is activated by the UV light. Experimental data were used to determine adsorption equilibrium constants for acetone, and to determine reaction rate constants assuming a Langmuir-Hinshelwood type rate expression.

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