Structure of Alkali Metal-Catalyzed Butadiene Polymers

1953 ◽  
Vol 26 (3) ◽  
pp. 522-527
Author(s):  
A. W. Meyer ◽  
R. R. Hampton ◽  
J. A. Davison
Keyword(s):  
Transition Temperature ◽  
Alkali Metal ◽  
Infrared Absorption ◽  
Styrene Copolymers ◽  
A Value ◽  
Second Order Transition ◽  
Metal Catalyzed ◽  
Sodium And Potassium ◽  
Absorption Measurements ◽  
Butadiene Styrene

Abstract The structures of various sodium and potassium-catalyzed butadiene polymers were determined from infrared absorption measurements. All of the polymers had a higher proportion of butadiene in the 1,2-configuration (45–80 per cent) than emulsion polybutadiene (18–23 per cent). Polybutadienes catalyzed by potassium had 15–20 per cent less butadiene in the 1,2-configuration than those in which sodium was the catalyst. When a mixture of sodium and potassium was used, the results were nearly the same as with the potassium catalyst alone. Polybutadienes made at 5° had 10 to 15 per cent more butadiene in the 1,2-configuration than those made at 45°. Diluent type had little or no effect on the structure of the polybutadienes. The butadiene portions of butadiene-styrene copolymers were found to have the same relative proportions of 1,2-, cis-1,4- and trans-1,4-configurations as the butadiene homopolymers. The second order transition temperature of sodium-catalyzed polybutadiene polymerized at 30° was −45°, whereas the 75° polybutadiene had a value of −64°.

Low-Temperature Properties of Plasticized Butadiene-Styrene Copolymers

1955 ◽  
Vol 28 (2) ◽  
pp. 557-569 ◽  
Author(s):  
D. A. Henderson ◽  
L. A. McLeod
Keyword(s):  
Transition Temperature ◽  
Low Temperature ◽  
Second Order ◽  
Order Transition ◽  
Styrene Copolymers ◽  
Second Order Transition ◽  
Dibutyl Sebacate ◽  
Special Case ◽  
Measured Transition ◽  
Butadiene Styrene

Abstract The second-order transition temperatures of plasticized butadiene-styrene copolymers have been measured by dilatometric techniques. In a series of ester plasticizers, the ability of a given plasticizer to depress the second-order transition temperature of the polymer is related to the swelling effect of the plasticizer on the polymer. The special case of a crystallizing plasticizer (dibutyl sebacate) has been discussed. Common petroleum plasticizers do not appear to behave in a similar manner. The change of coefficient of expansion of the ester-plasticized copolymers is related to the measured transition temperature of the blend.

Far-Infrared Absorption in Bulk Samples of Superconducting d-h.c.p. Lanthanum

1972 ◽  
Vol 50 (20) ◽  
pp. 2549-2551
Author(s):  
L. W. Kry ◽  
D. Hemming
Keyword(s):  
Infrared Absorption ◽  
Far Infrared ◽  
A Value ◽  
Gap Width ◽  
Absorption Measurements

Far-infrared absorption measurements have been made on bulk samples of d-h.c.p. lanthanum and the results indicate a gap width, 2Δ, of 11.6 ± 0.3 cm−1 or 1.44 ± 0.04 meV. Using a value of Tc = 4.87 ± 0.02 °K, taken from the literature, this gives 2Δ = (3.43 ± 0.09)kTc.

Quantitative Infrared Absorption Measurements on Tri-n-Butyl Phosphate

1980 ◽  
Vol 34 (4) ◽  
pp. 415-417 ◽  
Author(s):  
Vincent P. Tomaselli ◽  
Hassan Zarrabi ◽  
K. D. Möller
Keyword(s):  
Infrared Absorption ◽  
Molar Absorptivity ◽  
Measured Data ◽  
Pure Liquid ◽  
Absorption Bands ◽  
A Value ◽  
Self Association ◽  
Solvent Molecules ◽  
Infrared Absorption Bands ◽  
Absorption Measurements

The molar absorptivity, ε(ν̄) of three intense infrared absorption bands in tri- n-butyl phosphate has been measured as a function of concentration. For all three bands, ε(ν̄) is independent of concentration for dilute solutions, then decreases uniformly with increasing concentration, and finally becomes independent of concentration again as one approaches the pure liquid. A saturation effect is found at about 1.0 M for all cases. Deviations from Beer's law behavior are observed at concentrations which depend upon the absorption band and/or the choice of nonpolar solvent. Self-association of the solute molecules is considered to be the cause of the decrease in ε(ν̄) with increasing concentration. From the measured data, it is possible to estimate the number of solvent molecules required to prevent this self-association. For CCl4, we find this value to be 25 molecules of solvent per solute molecule, a value in agreement with elementary geometric consideration.

scholarly journals The Effect of Alkali Metal (Na, K) Doping on Thermochromic Properties of VO2 Films

MRS Advances ◽  
2018 ◽  
Vol 3 (32) ◽  
pp. 1863-1869 ◽  
Author(s):  
Işıl Top ◽  
Johannes Schläfer ◽  
Russell Binions ◽  
Ioannis Papakonstantinou ◽  
Sriluxmi Srimurugananthan ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Alkali Metal ◽  
Vanadium Dioxide ◽  
Sol Gel ◽  
Critical Transition Temperature ◽  
Low Temperature Annealing ◽  
Thermochromic Properties ◽  
Metal Doped ◽  
Sodium And Potassium ◽  
Vanadium Dioxide Thin Films

ABSTRACT:This work reports the synthesis of undoped and alkali metal doped thermochromic vanadium dioxide thin films by sol-gel spin coating and subsequent low-temperature annealing at 450 °C in N2-H2 atmosphere. The effect of sodium and potassium on the phase transition temperature as well as on the solar modulations were investigated. A dopant concentration of 0.3 at% resulted in a reduction of the critical transition temperature (Tc) from 62 °C to 57 °C and 47 °C for the sodium and potassium doped films, respectively. Moreover, both dopants improved the solar modulations (ΔTsol) of the undoped VO2 films from 3.81 to 9.44 and 5.43 %, respectively.

FURTHER DEVELOPMENTS IN THE VISTEX METHOD FOR THE DETERMINATION OF THE INTRINSIC VISCOSITY OF HIGH POLYMERS

1949 ◽  
Vol 27b (7) ◽  
pp. 666-681 ◽  
Author(s):  
D. A. Henderson ◽  
N. R. Legge
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Average Molecular Weight ◽  
Solvent Mixture ◽  
Gel Point ◽  
Styrene Copolymers ◽  
A Value ◽  
Pure Solvent ◽  
Butadiene Styrene

The intrinsic "vistex" viscosities of several series of butadiene–styrene copolymers of varying conversion and average molecular weight, dissolved directly from the latex in the vistex solvent mixture (toluene–isopropanol, 80/20 by volume), have been investigated and compared with the intrinsic viscosities of the corresponding coagulated, dried polymers dissolved in toluene. The intrinsic viscosity in toluene, [η]T, is related to the intrinsic vistex viscosity, [η]V, in toluene–isopropanol by the equation:—[Formula: see text]Hence, viscosity average molecular weight may be calculated from vistex measurements.A further development of the method has shown that, once the latex is dissolved in the vistex solvent, the solution may be diluted, within certain denned limits, by the addition of pure solvent (toluene) to obtain the several levels of concentration of polymer required for the determination of intrinsic viscosity. It is then possible, by extrapolation to zero concentration of polymer, to obtain a value for the intrinsic viscosity that is equal to the conventional intrinsic viscosity of the polymer in pure solvent after coagulation and drying under very mild conditions. The viscosity characteristics of butadiene–styrene copolymers of varying conversion appear to be represented, at conversions below the gel point, by the equation,[Formula: see text]where β′ and n are constants of the order of 0.25 and 1 for solutions in toluene and 0.1 and 2.5 respectively for vistex solutions. Distinct changes in β and/or n have been found at conversions in the region of and beyond the gel point.

The Effect of Comonomer on the Microstructure of Butadiene Copolymers

1953 ◽  
Vol 26 (4) ◽  
pp. 832-839
Author(s):  
Frederick C. Foster ◽  
John L. Binder
Keyword(s):  
Infrared Absorption ◽  
Theoretical Explanation ◽  
Experimental Results ◽  
Vinyl Monomers ◽  
Styrene Copolymers ◽  
Wide Range ◽  
Styrene Content ◽  
Comonomer Content ◽  
Butadiene Styrene

Abstract The microstructure of butadiene-styrene copolymers having a wide range of styrene contents has been determined by infrared absorption. The results demonstrate that the percentage of trans-1,4-addition increases, the 1,2-addition decreases, and the cis-1,4-addition decreases as the styrene content is increased. Similar measurements of five other butadiene copolymer systems indicate that all these vinyl monomers, acrylonitrile, methacrylonitrile, methylvinyl ketone, vinylpyridine, and α-methylstyrene, change the microstructure in the same direction as styrene, differing only in the magnitude of their effect. A theoretical explanation, consistent with the experimental results obtained, is given for the change in microstructure with comonomer content.

Microstructures of Polybutadienes and Butadiene-Styrene Copolymers

1955 ◽  
Vol 28 (1) ◽  
pp. 121-130
Author(s):  
John L. Binder
Keyword(s):  
Alkali Metal ◽  
Physical Properties ◽  
Metal Catalysts ◽  
Maximum Amount ◽  
Styrene Copolymers ◽  
Emulsion Systems ◽  
Emulsion Polymerizations ◽  
Increasing Temperature ◽  
Butadiene Styrene

Abstract Polybutadienes and butadiene-styrene copolymers were prepared to study the effect of recipe variables on the physical properties and to learn whether there are correlations between the microstructures and physical properties. The changes in the microstructure of emulsion polybutadienes and butadiene-styrene copolymers of the types studied, which can be produced by either recipe variables or changes in temperature, are limited. The maximum amount of cis-1,4-addition amounted to 23 per cent (in the butadiene part of butadienestyrene copolymers) at 100° C, the maximum amount of trans-1,4- was about 80 per cent at −35° C, and the maximum amount of 1,2-addition was about 20 per cent. While the amount of cis-1,4-addition increases with increasing temperature, it is unlikely that polymers containing even 50 per cent cis-1,4-addition can be made at practical temperatures in emulsion systems. The structures of polybutadienes may be changed markedly by alkali-metal catalysts. The structure is affected by the kind of catalyst, by the temperature, and by promotors. Emulsion polymerizations are not likely to yield improved polymers for practical uses, but much can be done to tailor polymers for specific uses by using alkali-metal catalysts in bulk or solution systems.

Alkali metal catalyzed carbon dioxide gasification of carbon

1992 ◽  
Vol 6 (4) ◽  
pp. 343-351 ◽  
Author(s):  
Toshimitsu Suzuki ◽  
Hiroyuki Ohme ◽  
Yoshihisa Watanabe
Keyword(s):  
Carbon Dioxide ◽  
Alkali Metal ◽  
Gasification Of Carbon ◽  
Metal Catalyzed ◽  
Carbon Dioxide Gasification
Sign in / Sign up

Export Citation Format

Share Document