X-Ray Studies of Low-Temperature Polybutadiene and Butadiene-Styrene Copolymers

1949 ◽  
Vol 22 (2) ◽  
pp. 356-369 ◽  
Author(s):  
Karl E. Beu ◽  
W. B. Reynolds ◽  
C. F. Fryling ◽  
H. L. McMurry
Keyword(s):  
Molecular Weight ◽  
Low Temperature ◽  
Polymer Chains ◽  
Polymerization Temperature ◽  
X Ray ◽  
Styrene Copolymers ◽  
Emulsion Polymerizations ◽  
Diffraction Patterns ◽  
Ray Patterns ◽  
Butadiene Styrene

Abstract Although it is now generally recognized that the temperature of polymerization affects profoundly the properties of emulsion elastomers, there is very little evidence available pertaining to the cause of the variations of properties. It is felt by some that the improved properties of low-temperature elastomers can be related to variations in molecular weight and molecular-weight distribution. In this laboratory, however, the opinion has prevailed that the lower emulsion polymerization temperatures appreciably alter the fine structure of the molecules with an increase in the regularity of the polymer chains. If there were actually less branching and cross-linking in low-temperature polymers, and less 1,2-addition to monomer components, the increased order should be evident from x-ray diffraction patterns. To provide information on the above questions, x-ray studies were made with four purposes in view: (1) to determine the effect of polymerization temperature on the crystallization properties of unstretched and stretched polybutadienes; (2) to determine the influence of styrene content on the crystallization of butadiene-styrene copolymers; (3) to study some effects of compounding and vulcanization on crystallizable polybutadiene; and (4) to use the preferred orientation patterns obtained from some of these polymers for structural evaluations. To accomplish these objectives, x-ray patterns were obtained at several temperatures of some unstretched and stretched polybutadiene polymers, butadiene-styrene copolymers, and a vulcanized and compounded polybutadiene. The polybutadienes were prepared by emulsion polymerizations at 55°, 40°, 30°, 20°, 5°, −10° and −20° C. Since the −20° C polybutadiene showed the most marked crystallization patterns, the effects of compounding and of styrene addition were studied, using polymers prepared at this temperature for comparison. Three butadiene-styrene copolymers containing, respectively, 10, 20, and 30 per cent styrene in the monomer charge and one vulcanized polybutadiene compounded with Wyex carbon black were studied.

X-ray studies of low-temperature polybutadiene and butadiene-styrene copolymers

1948 ◽  
Vol 3 (4) ◽  
pp. 465-480 ◽  
Author(s):  
Karl E. Beu ◽  
W. B. Reynolds ◽  
C. F. Fryling ◽  
H. L. McMurry
Keyword(s):  
Low Temperature ◽  
X Ray ◽  
Styrene Copolymers ◽  
Butadiene Styrene

Examination of Rabbit Fc Crystals

1968 ◽  
Vol 26 ◽  
pp. 140-141
Author(s):  
J. P. Robinson ◽  
P. G. Lenhert
Keyword(s):  
Molecular Weight ◽  
Flat Plate ◽  
Phosphate Buffer ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutral Ph ◽  
Small Crystals ◽  
Carbon Coated ◽  
Diffraction Patterns

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.

Effect of Temperature on Ozone Cracking of Rubbers

1966 ◽  
Vol 39 (3) ◽  
pp. 643-650
Author(s):  
A. N. Gent ◽  
J. E. McGrath
Keyword(s):  
Polymer Chains ◽  
Effect Of Temperature ◽  
Ozone Molecule ◽  
Segmental Mobility ◽  
Network Chain ◽  
Styrene Copolymers ◽  
Rates Of Growth ◽  
Rate Controlling Step ◽  
Limiting Value ◽  
Butadiene Styrene

Abstract The rates of growth of single ozone cracks have been measured for vulcanizates of a series of butadiene—styrene copolymers, over a temperature range from − 5° C to 95° C. The rates appear to be determined by two mechanisms. At low temperatures, near the glass transition temperature, they are quantitatively related to the segmental mobility of the polymer. The principal rate-controlling step in this case is concluded to be movement of the polymer chains after scission to yield new surface. At high temperatures the rate approaches a limiting value of 10−3 cm/sec/mg of ozone/1. This is about 1/1000 of the maximum possible value when instantaneous reaction of one incident ozone molecule causes scission of one network chain.

Structure of Cerebrosides. II. Small Angle X-Ray Diffraction Study of Cerasine

1979 ◽  
Vol 34 (12) ◽  
pp. 1121-1124 ◽  
Author(s):  
R. Hosemann ◽  
J. Loboda-Čačković ◽  
H. Čačković ◽  
S. Fernandez-Bermúdez ◽  
F. J. Baltá-Calleja
Keyword(s):  
Molecular Weight ◽  
Fatty Acid ◽  
Hydrogen Atom ◽  
Low Temperature ◽  
Hydroxyl Group ◽  
X Ray Diffraction ◽  
Orientational Disorder ◽  
X Ray ◽  
Long Period ◽  
Lattice Planes

Cerasine having a molecular weight of 800 differs chemically from phrenosine only in the hydroxyl group attached to the fatty acid tail which is replaced by a hydrogen atom. Nevertheless, remarkable differences between both cerebrosides are detected in the lamellae periodicities. In the range of 23 - 66 °C just one single (instead of two) structure with a similar subcell to the triclinic one component of phrenosine is detected. Between 66 and 87 °C three new components (instead of one in phrenosine) appear. Two of the structures are similar to the two phrenosine-components at low temperature and the tilt angles of their chains with respect to the basal planes can explain the stabilizing capacity of the 201 and 301 netplanes of the paraffin-like subcells respectively. These lattice planes are parallely aligned to the surfaces of the lamellae. The long period of 58 Å of component II cannot be explained in such a wav. This period persits upto 105 °C and coexists from 87 °C with a new component showing a 40 Å-periodicity, which cannot either be explained in the above manner. Paracrystalline distortions of the arrangement of the bilayers can be justified by orientational disorder of the galactose heads.

Apparent Activation Energy in Low Temperature Aging of Y-TZP Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 100-103
Author(s):  
Qi Fei Xie ◽  
Cheng Wang ◽  
Qing Feng Zan ◽  
Li Min Dong
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Apparent Activation Energy ◽  
Coordinate Systems ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Temperature Aging ◽  
Diffraction Patterns ◽  
Straight Lines ◽  
Temperature Aging

Apparent activation energy in low temperature aging of two kinds of Y-TZP ceramic was studied in this paper. The ceramics were processed into small pieces, and aging in 100°C, 110°C, 120°C, 130°C and 140°C respectively. The content of monoclinic phase was calculated by X-ray diffraction patterns and the microstructure was scanned by SEM. According to MAJ law and Arrhenius formation, straight lines were fitted in coordinate systems of ln (ln (1/(1 − f )))-ln t and ln b-1/T, and the kinetic parameters of low temperature aging of Y-TZP ceramic were calculated according to these lines. The results revealed that grain size significantly affected apparent activation energy of Y-TZP ceramics.

Properties of Random and Block Copolymers of Butadiene and Styrene. III. Three Sequence Styrene-Butadiene-Styrene Block Polymers

1967 ◽  
Vol 40 (4) ◽  
pp. 1183-1199 ◽  
Author(s):  
C. W. Childers ◽  
G. Kraus
Keyword(s):  
Tensile Strength ◽  
Block Copolymers ◽  
Polymer Chains ◽  
Two Phase ◽  
Styrene Copolymers ◽  
Relaxation Measurements ◽  
Styrene Butadiene Styrene ◽  
Increasing Temperature ◽  
Styrene Butadiene ◽  
Butadiene Styrene

Abstract In butadiene styrene copolymers containing long block sequences chain segments associate with like segments to form a two phase structure. Properties of such polymers are dependent not only on composition and molecular weight but also on block sequence along the chain. Polymers containing two or more polystyrene blocks per molecule form networks and exhibit elastomeric properties in the uncured state resembling those of filler reinforced vulcanizates. This behavior is shown both by linear styrene-butadiene-styrene elastomers and multichain block copolymers branched in the polybutadiene blocks. A prominent loss tangent peak was observed around —40° C for the multichain polymers. Stress strain following prestretching and stress relaxation measurements indicate some shifting of polystyrene associations during stretching. Tensile strength is reduced by increasing temperature and addition of plasticizers. Reinforcement by polystyrene domains in vulcanized block copolymers is evident from tensile strength, dynamic modulus, and swelling measurements, but decreases with increased crosslinking. The number of styrene sequences in the primary molecules is less important after vulcanization as crosslinking destroys the individuality of the original polymer chains.

The determination of composition and thermal history of plagioclase by the X-ray powder method

1955 ◽  
Vol 30 (229) ◽  
pp. 648-656 ◽  
Author(s):  
J. Goodyear ◽  
W. J. Duffin
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Similar Composition ◽  
X Ray ◽  
Naturally Occurring ◽  
Cell Dimensions ◽  
History Of ◽  
Unit Cell Dimensions ◽  
Ray Patterns

In a recent paper (hereafter referred to as GD) Goodyear and Dufiln (1954) described X-ray powder data for a number of synthetic and chemically analysed plagioclases of composition An0Abl00-Anl00Ab0. Important aspects of this work were a correlation of the X-ray patterns with chemical composition, and a distinction between the pattern of a naturally occurring material of low-temperature origin and that of a synthetic of similar composition. The investigation showed quite clearly that the unit-cell dimensions of a synthetic plagioelase depend but little on composition from An0Abl00 to An70Ab30, whilst they differ from those of the low-temperature modification greatly for albite, to a lessening degree as the composition approaches An70Ab30, and practically not at all in the range An70Ab30-Anl00Ab0.

Solvothermal route to Bi3Se4 nanorods at low temperature

2001 ◽  
Vol 16 (12) ◽  
pp. 3361-3365 ◽  
Author(s):  
Yuan-fang Liu ◽  
Jing-hui Zeng ◽  
Wei-xin Zhang ◽  
Wei-chao Yu ◽  
Yi-tai Qian ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Reaction Mechanism ◽  
Low Temperature ◽  
Hydrazine Hydrate ◽  
Photoelectron Spectra ◽  
Elemental Selenium ◽  
X Ray ◽  
Transmission Electron ◽  
Microscope Images ◽  
Diffraction Patterns

Nanorods Bi3Se4 were synthesized directly through the reaction between BiCl3 and elemental selenium in an autoclave with hydrazine hydrate as solvent at 165 °C for 10 h. X-ray powder diffraction patterns, x-ray photoelectron spectra, and transmission electron microscope images show that the products are well-crystallized hexagonal Bi3Se4 nanorods. The solvent hydrazine hydrate played an important role in formation and growth of Bi3Se4 nanorods. The possible reaction mechanism was proposed.

Sign in / Sign up

Export Citation Format

Share Document