Theory of Rubber Elasticity for Development of Synthetic Rubbers

1943 ◽  
Vol 16 (2) ◽  
pp. 286-289
Author(s):  
Hubert M. James ◽  
Eugene Guth
Keyword(s):  
Long Range ◽  
Characteristic Property ◽  
Raw Materials ◽  
Rubber Elasticity

Abstract Two cardinal problems exist in connection with the production of synthetic rubbers: (1) choice of the type of synthetics, necessary raw materials, and methods of production, and (2) evaluation of the products obtained. The most important and characteristic property of synthetics (and of natural rubbers) is their long-range reversible elasticity.

The Chronology of the Neolithic Necropolis Bòbila Maduell-Can Gambús in the Northeast Iberian Peninsula: Dating the Pit Burials Cultural Horizon and Long-Range Raw Material Exchange Networks

Radiocarbon ◽  
2017 ◽  
Vol 59 (6) ◽  
pp. 1713-1736 ◽  
Author(s):  
Juan F Gibaja ◽  
Berta Morell ◽  
Juan Antonio Barceló Álvarez ◽  
Stéphanie Duboscq ◽  
Alba Masclans ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Long Range ◽  
Bayesian Modeling ◽  
Temporal Dynamics ◽  
Raw Materials ◽  
Statistical Analyses ◽  
Raw Material ◽  
Exchange Networks ◽  
Material Exchange

ABSTRACTBòbila Madurell-Can Gambús is the most emblematic Neolithic cemetery in the northeastern Iberian peninsula, with a total of 179 documented pit burials. Artifacts made of exogenous raw materials, such as honey flint (southeastern France), jadeite, amphibolite, eclogite and nephrite (Alps and the Pyrenees), variscite (coast of northeastern Iberia), and even obsidian (Sardinia), have been found in the burials. The presence of these raw materials is not exclusive to this necropolis, but they have also been documented in many of the graves of this region during this period. The literature has singled out this funerary practice as the Pit Burials cultural horizon. However, until now the chronology of this funerary practice has not been fully defined, so it was difficult to explain the development of the chronology and the networks through which the materials reached northeast Iberia. New, unpublished radiocarbon (14C) dates of Bòbila Madurell-Can Gambús are presented, as well as the results of different statistical analyses and Bayesian modeling that specify its chronology. Through the contribution of new data on the chronology of Bòbila Madurell-Can Gambús new clues regarding the temporal dynamics of pit burials and the raw materials exchange networks associated with them are presented.

Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

1988 ◽  
Vol 46 ◽  
pp. 582-583
Author(s):  
C. J. Chan ◽  
K. R. Venkatachari ◽  
W. M. Kriven ◽  
J. F. Young
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Shape Change ◽  
Microstructural Characterization ◽  
Particle Size Effect ◽  
Dicalcium Silicate ◽  
Laser Melting ◽  
Uniform Size ◽  
Cell Shape Change ◽  
Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

Crystallization of barium hexaferrite

1992 ◽  
Vol 50 (1) ◽  
pp. 362-363
Author(s):  
Chung-kook Lee ◽  
Yolande Berta ◽  
Robert F. Speyer
Keyword(s):  
Size Distribution ◽  
Raw Materials ◽  
Barium Hexaferrite ◽  
Recording Media ◽  
Magnetic Recording Media ◽  
Promising Candidate ◽  
Crystallization Method ◽  
Temperature Heat ◽  
High Density Magnetic Recording ◽  
Temperature Heat Treatment

Barium hexaferrite (BaFe12O19) is a promising candidate for high density magnetic recording media due to its superior magnetic properties. For particulate recording media, nano-sized single crystalline powders with a narrow size distribution are a primary application requirement. The glass-crystallization method is preferred because of the controllability of crystallization kinetics, hence, particle size and size distribution. A disadvantage of this method is the need to melt raw materials at high temperatures with non-reactive crucibles, e.g. platinum. However, in this work, we have shown that crystal growth of barium hexaferrite occurred during low temperature heat treatment of raw batches.

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