Synthesis and Elastomeric Properties of Copolymers of Butadiene and 1,3-Pentadiene

1973 ◽  
Vol 46 (5) ◽  
pp. 1274-1284 ◽  
Author(s):  
A. Carbonaro ◽  
V. Zamboni ◽  
G. Novajra ◽  
G. Dall'Asta
Keyword(s):  
Abrasion Resistance ◽  
Room Temperature ◽  
Composition Range ◽  
General Purpose ◽  
Random Copolymers ◽  
Technological Properties ◽  
Vanadium Compounds ◽  
Catalyst Systems ◽  
Trans Structure ◽  
Aluminum Halides

Abstract Random copolymers of all trans structure have been prepared from butadiene and 1,3-pentadiene, in the presence of vanadium compounds and alkyl aluminum halides composed catalyst systems. Copolymers of butadiene and pentadiene, in the composition range of 30-45 weight per cent of pentadiene, are amorphous at room temperature at rest but crystallize upon stretching. Cured tread stocks show improved technological properties with respect to other synthetic diene-based elastomers. Very good processing and extrusion behavior, high tack, tear strength, and abrasion resistance are outstanding properties of the BP copolymers in the field of general purpose rubbers.

Ethylene Propylene Terpolymers

1967 ◽  
Vol 40 (2) ◽  
pp. 569-589 ◽  
Author(s):  
R. German ◽  
G. Vaughan ◽  
R. Hank
Keyword(s):  
Molecular Weight ◽  
Raw Materials ◽  
General Purpose ◽  
Random Copolymers ◽  
Technological Properties ◽  
Ethylene Propylene ◽  
The Third ◽  
Low Degrees ◽  
Accelerator System ◽  
Controlled Structures

Abstract The general technological properties of a polymer are closely related to its molecular structure. It is, therefore, important to know polymerization methods by which to produce reproducible polymers with controlled structures. Use of several monomers in copolymerization significantly increases the difficulty of this problem, but in the end it leads to a much wider spectrum of raw materials. In addition to variations caused by changes in molecular weight and in molecular weight distribution the nature of copolymers may be altered by changing the composition of the monomer mixture and the way monomers are distributed in the polymer chain. Use of Ziegler-Natta catalysts has already given a multiplicity of materials composed of ethylene and propylene: random copolymers are particularly interesting as rubbers. Introduction of a third component to give unsaturation in the terpolymer, so that this may be vulcanized with sulfur and accelerators, has greatly increased the possible areas of application for these polymers. Utility of a diene as the third component to give EPT's which can be used as general purpose rubbers depends on its price, the ease with which it copolymerizes through one double bond, its influence on the velocity or steric course of the ethylene-propylene copolymerization, vulcanization characteristics of the resulting terpolymers, and finally on the technological properties of the vulcanizates. The amount of copolymerized termonomer should be limited to retain the advantageous chemical and physical properties of the original ethylene-propylene copolymers. However very low degrees of unsaturation limit the sulfur and accelerator system, the characteristics of which depend strongly on the structure of the terpolymer as well as on the nature and form of the vulcanization agent. It is therefore essential to have a thorough understanding of this multiple interdependency for optimal application of the materials. We describe here reproducible procedures for production of terpolymers with controlled structures, and the course of vulcanization of the products in relation to terpolymer structure. We shall describe methods, based on these investigations, which may be applied for control of the vulcanization characteristics of the polymers.

MAGNESIUM AZ31B

Alloy Digest ◽  
1962 ◽  
Vol 11 (9) ◽  
Keyword(s):  
High Temperature ◽  
Magnesium Alloy ◽  
Physical Properties ◽  
Room Temperature ◽  
Heat Treating ◽  
General Purpose ◽  
Bearing Strength ◽  
Temperature Performance ◽  
Wrought Magnesium Alloy ◽  
Metal Products

Abstract Magnesium AZ31B is a general purpose wrought magnesium alloy for room temperature service. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive, shear, and bearing strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Mg-53. Producer or source: The Dow Metal Products Company.

Low-Temperature Mechanical Alloying Of Cu-Fe and Cu-Ta Powders

1997 ◽  
Vol 481 ◽  
Author(s):  
J.-H. He ◽  
E. Ma
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Composition Range ◽  
Dynamic Balance ◽  
Liquid Nitrogen Temperature ◽  
Phase Region ◽  
Two Phase ◽  
Forced Mixing ◽  
Single Phase Formation ◽  
Nonequilibrium Vacancies

ABSTRACTA model analysis is presented which explains ball-milling induced alloying in positive-heatof- mixing systems in terms of a dynamic balance between externally forced mixing and thermal phase decomposition mediated by deformation-enhanced population of defects. The possibility of eliminating the thermal decomposition to force single phase formation is examined by milling Cu- Fe and Cu-Ta powder mixtures at the liquid nitrogen temperature (LN2T). Over a range of compositions for Cu-Fe and almost the entire composition range for Cu-Ta, the two-phase region observed for room-temperature (RT) milling persisted after cryomilling. The moderate temperature dependence of milling-induced alloying is interpreted by analyzing the dynamics of the generation and annihilation of the nonequilibrium vacancies during deformation and impacts in a SPEX mill.

The formation of γ-caseins during cooling of raw milk

1979 ◽  
Vol 46 (2) ◽  
pp. 219-221 ◽  
Author(s):  
Ernst H. Reimerdes ◽  
Erika Herlitz
Keyword(s):  
Room Temperature ◽  
Serine Proteinase ◽  
Raw Milk ◽  
Time Dependent ◽  
Proteolytic Degradation ◽  
Technological Properties ◽  
Milk Processing ◽  
Milk Serum ◽  
Simple Extraction ◽  
Micelle Surface

SUMMARYIt has been shown that there is a time-dependent transfer of β-casein and the milk serine proteinase system from micelles to milk serum with change of temperature from 38 to 4 °C. It has been established that the γ-caseins can be formed by proteolytic degradation of β-casein. By a simple extraction technique, the very hydrophobic γ-casein fraction was separated from stored milks (26 and 4 °C) and estimated quantitatively. The results showed that the proteolytic degradation of β-casein is faster at 4 °C than at room temperature and this can be explained by the immobilization of enzyme and substrate at the micelle surface at higher temperatures (26 °C).The results indicate that irreversible changes during cooling for short periods do not cause problems in milk processing, but the formation of γ-caseins and phosphopeptides may influence the technological properties of raw milk stored for more than 48 h.

Numerical Simulation and Optimization for 900V 4H-SiC DiMOSFET Fabrication

2005 ◽  
Vol 483-485 ◽  
pp. 793-796 ◽  
Author(s):  
Sang Cheol Kim ◽  
Wook Bahng ◽  
Nam Kyun Kim ◽  
Eun Dong Kim ◽  
T. Ayalew ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Breakdown Voltage ◽  
Room Temperature ◽  
General Purpose ◽  
Half Cell ◽  
Trade Off ◽  
Simulation And Optimization ◽  
Edge Termination ◽  
Well Spacing ◽  
Simulation Results

We report the simulation results of 25µm half cell pitch vertical type 4H-SiC DiMOSFET using the general-purpose device simulator MINIMOS-NT. The best trade-off between breakdown voltage and on-resistance in terms of BFOM is around 19MW/cm2 with a p-well spacing 5µm. The specific on -resistance, RON, sp, simulated with VGS=10V and VDS=1V at room temperature, is around 22.76mWcm2. An 900V breakdown voltage is simulated with ion-implanted edge termination.

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