X-Ray Analysis of the Molecular Structure of Rubbers. X-Ray Diffraction of Amorphous Rubber

1952 ◽  
Vol 25 (2) ◽  
pp. 258-264 ◽  
Author(s):  
V. I. Kasatochkin ◽  
B. V. Lukin
Keyword(s):  
Molecular Structure ◽  
Natural Rubber ◽  
Crystalline Phase ◽  
X Ray Diffraction ◽  
Amorphous Halo ◽  
Crystallization Property ◽  
X Ray ◽  
Synthetic Rubber ◽  
Continuous Background ◽  
Diffraction Patterns

Abstract The potentialities of x-ray analysis of the molecular structure of rubbers can be widely extended by measuring the intensities of the amorphous halo and continuous background of scattering in the diffraction patterns of unstretched test-specimens. This method can be applied to the study of the effect of repeated stretching of rubbers. Questions pertaining to the fatigue of rubbers have immense importance now in the performance of rubber products. The methods of determining the crystallization of natural rubber and of measuring the intensity of the amorphous halo for synthetic rubber were employed for investigating the changes of the molecular structure of rubber due to repeated stretching. The crystallization of raw smoked-sheet rubber decreased as a result of fatigue; a similar phenomenon was observed for its vulcanizates. The vulcanizates which were stretched less than 300 per cent lost their crystallization property altogether after fatigue, and, at greater elongations, the content of the crystalline phase greatly decreased (see Figure 1).

Properties of Some Synthetic Rubbers

1943 ◽  
Vol 16 (4) ◽  
pp. 857-862
Author(s):  
L. B. Sebrell ◽  
R. P. Dinsmore
Keyword(s):  
Molecular Structure ◽  
Natural Rubber ◽  
Point Of View ◽  
General Point ◽  
Chain Molecules ◽  
X Ray ◽  
Synthetic Rubber ◽  
The Difference ◽  
Diffraction Patterns ◽  
Long Chain

Abstract X-RAY STRUCTURE OF SYNTHETIC RUBBER In presenting a series of x-ray diagrams of various types of synthetic rubber in comparison with natural rubber, in both the stretched and the unstretched condition, it is our purpose to bring out the fact that the molecular structure of synthetic rubbers is entirely different from that of natural rubber. It is proposed also to review briefly the theories which have been advanced, based on the x-ray analysis of rubber, to account for the elasticity of natural rubber, and to advance the possible reason for the difference shown by the x-ray diagrams of synthetic rubber. At the present time, from the most general point of view, the molecular structure of a rubberlike material is envisaged as a sort of brush-heap structure of entangled long chain molecules. x-Ray diffraction patterns show that, for some rubberlike materials, notable regularities of structure sometimes occur in the tangle of long-chain molecules. It is now realized that these regularities are not essential for rubberlike behavior. Nevertheless their observation and study is important because they afford a unique opportunity for studying the molecular structure of the chains and the molecular rearrangements which occur with the application of stress.

Nature of Stark Rubber

1955 ◽  
Vol 28 (4) ◽  
pp. 1007-1020 ◽  
Author(s):  
Donald E. Roberts ◽  
Leo Mandelkern
Keyword(s):  
Natural Rubber ◽  
Melting Temperature ◽  
Melting Behavior ◽  
X Ray Diffraction ◽  
Equilibrium Melting Temperature ◽  
X Ray ◽  
Melting Temperatures ◽  
Controlled Conditions ◽  
Previous Assignment ◽  
Diffraction Patterns

Abstract The melting behavior and x-ray diffraction patterns of four different samples of stark rubber have been investigated. The melting temperatures, 39° to 45.5° C, are substantially higher than that observed for natural rubber crystallized by cooling. The x-ray diffraction patterns indicate that the crystallites in stark rubber are oriented. This observation can explain the higher melting temperatures. Thus, the previous assignment of an equilibrium melting temperature, 28° (±1°) C, to unoriented crystalline natural rubber is shown to be appropriate. Several different methods that have been used successfully in preparing stark rubber under controlled conditions in the laboratory are outlined.

The Structure and Porosity of Fe62-xCo10WyMexY8B20-y Alloys in the Amorphous and Crystalline States (where: Me = Mo, Nb; x = 0, 1, 2; y = 0, 1, 2)

2017 ◽  
Vol 68 (1) ◽  
pp. 22-27
Author(s):  
Marcin Nabialek ◽  
Pawel Pietrusiewicz ◽  
Michal Szota ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Andrei Victor Sandu
Keyword(s):  
Pore Diameter ◽  
Copper Plate ◽  
X Ray Diffraction ◽  
Amorphous Halo ◽  
Casting Method ◽  
Average Pore ◽  
X Ray ◽  
Crystallization Method ◽  
Injection Casting ◽  
Diffraction Patterns

The investigated crystalline and amorphous samples were obtained by crystallization of the liquid alloy on a water-cooled copper plate and by an injection-casting method, respectively. In each case, the structure of the samples was determined by examination of the obtained X-ray diffraction patterns. The diffraction patterns of samples produced by the injection casting method were characterized by a single broad peak called the amorphous halo. The samples produced by the crystallization method were shown to feature within their structure the following phases:YB2, Fe2Y, �-Fe, Co5Y, and B6Co23. Further research, performed using computer tomography, revealed the existence of pores within the samples. The crystalline-structure samples were found to feature a lower average pore diameter.

Assessment of the X-ray diffraction–absorption method for quantitative analysis of largely amorphous pharmaceutical composites

2003 ◽  
Vol 36 (1) ◽  
pp. 74-79 ◽  
Author(s):  
P. Bergese ◽  
I. Colombo ◽  
D. Gervasoni ◽  
Laura E. Depero
Keyword(s):  
Weight Fraction ◽  
Toxic Waste ◽  
X Ray Diffraction ◽  
Amorphous Halo ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Matrix ◽  
Diffraction Patterns ◽  
Challenging Question

Determination of the residual weight fraction of a crystalline drug in a largely amorphous pharmaceutical composite is still a challenging question. None of the quantitative X-ray diffraction (QXRD) methods found in the literature is suitable for these inclusion systems. The composite's diffraction patterns present a structured amorphous halo (arising from the amorphous matrix and drug molecular clusters) in which the crystalline drug peaks rise up. Moreover, the matrix traps a non-negligible quantity of water (which cannot be directly detected by X-ray diffraction) and the crystal structure of the drug may be unknown. In this work, a development of the QXRD analysis based on the diffraction–absorption technique is presented. The method is standardless, avoids the interpretation of the amorphous halo and the knowledge of the crystal structures of the phases, and takes into account the absorbed water. Results are in excellent agreement with those obtained by differential scanning calorimetry (DSC). The general features of the technique open its application to other classes of largely amorphous composite materials, like glass systems generated in the stabilization/solidification of toxic waste.

Modified palm stearin compatibilized natural rubber/halloysite nanotubes composites: Reinforcement versus strain-induced crystallization

2020 ◽  
pp. 009524432092857
Author(s):  
Nureeyah Jehsoh ◽  
Indra Surya ◽  
Kannika Sahakaro ◽  
Hanafi Ismail ◽  
Nabil Hayeemasae
Keyword(s):  
Natural Rubber ◽  
Palm Stearin ◽  
Halloysite Nanotubes ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Strain Induced Crystallization ◽  
Diffraction Patterns ◽  
The Relationship ◽  
Induced Crystallization

Natural rubber (NR) is known as hydrophobic material and is incompatible with hydrophilic filler such as halloysite nanotubes (HNTs). To overcome this obstacle, the compatibilizer is a material of choice to incorporate in such compound. In this study, bio-based compatibilizer was used which was prepared by modification of palm stearin. The presence of special functionalities of modified palm stearin (MPS) was confirmed by Fourier transform infrared (FTIR) analysis. It was then varied from 0.5 phr to 2 phr to the NR matrix. Here, the properties were evaluated through the mechanical properties with special attention to the relationship between their reinforcement and crystallization behavior after stretching. It was found that the addition of MPS significantly enhanced the modulus, tensile strength, and tear strength of the composites. This clearly corresponded to interaction between NR and HNT promoted by MPS. The FTIR spectrum, X-ray diffraction patterns, and scanning electron microscopy images were also utilized to verify the behavior of MPS in the NR/HNT composites. As for the crystallization of the composites, the results obtained from stress–strain curves are in very good agreement to the outputs observed by the synchrotron wide-angle X-ray scattering. This corresponding interaction of MPS has greatly influenced on assisting the strain-induced crystallization of composites.

The Molecular Structure and Hydrogen Bond Geometry in Liquid Formamide: Electron, Neutron, and X-Ray Diffraction Studies

1983 ◽  
Vol 38 (2) ◽  
pp. 231-236 ◽  
Author(s):  
E. Kálmán ◽  
I. Serke ◽  
G. Pálinkás ◽  
M. D. Zeidler ◽  
F. J. Wiesmann ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bond ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Free Molecule ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Mean ◽  
Diffraction Patterns ◽  
Good Agreement

Abstract Electron, neutron and X-ray diffraction patterns of liquid formamide have been measured at a temperature of 25 °C. Analysis of the diffraction data yields the molecular structure and the average geometry of the hydrogen bond. The molecular parameters obtained from liquid diffraction experiments are in good agreement with those from gas electron diffraction for the free molecule. The mean O…N and O…H hydrogen bond distances are 2.9 Å and 1.9 Å, respectively. Four H-bonds per molecule are found on the average. The deviation of the H-bonds from the linearity is estimated.

Acetylene Polymers and Their Derivatives. II. A New Synthetic Rubber: Chloroprene and Its Polymers

1932 ◽  
Vol 5 (1) ◽  
pp. 7-29
Author(s):  
Wallace H. Carothers ◽  
Ira Williams ◽  
Arnold M. Collins ◽  
James E. Kirby
Keyword(s):  
Particle Size ◽  
Natural Rubber ◽  
Petroleum Hydrocarbons ◽  
Tetracarboxylic Acid ◽  
Closed Vessel ◽  
X Ray Diffraction ◽  
Aqueous Emulsion ◽  
X Ray ◽  
Vulcanized Rubber ◽  
Synthetic Rubber

Abstract Chloro-2-butadiene-1,3 (chloroprene) is described and its structure established through reactions leading to its conversion into butane-α, β,γ,δ-tetracarboxylic acid, and into β-chloroanthraquinone. Within ten days under ordinary conditions in a closed vessel containing a little air, chloroprene spontaneously changes into a transparent, resilient, strong, non-plastic, elastic mass resembling vulcanized rubber. This product is called μ-polychloroprene. By interrupting the polymerization before it has proceeded to completion one obtains a soft, plastic product (α-polymer) that resembles unvulcanized rubber. Under the action of heat the α-polymer rapidly changes to the μ-polymer. Other polymers of chloroprene described are volatile (β-) polymer, granular (ω-) polymer, and balata-like polymer. The structures of the polymers are discussed as well as the effect of conditions on the formation of each type. Unlike any previously described synthetic rubbers, μ-polychloroprene resembles natural rubber in the fact that when it is stretched its x-ray diffraction pattern shows a point diagram. The transformation of chloroprene into μ-polychloroprene occurs very rapidly in aqueous emulsion. The resulting product constitutes a synthetic (vulcanized) latex. It has a much smaller particle size than natural latex and it penetrates porous materials more readily. Chloroprene can also be polymerized in the pores of porous or bibulous materials. The materials thus become intimately impregnated with synthetic rubber. Compared with natural rubber the new synthetic rubber is more dense, more resistant to absorption or penetration by water, less strongly swelled by petroleum hydrocarbons and less permeable to many gases. It is much more resistant to attack by oxygen, ozone, hydrogen chloride, hydrogen fluoride and many other chemicals.

The X-Ray Diagram of a Buna-S Vulcanizate

1945 ◽  
Vol 18 (1) ◽  
pp. 20-21
Author(s):  
Ross E. Morris ◽  
Charles B. Jordan
Keyword(s):  
Natural Rubber ◽  
Diffraction Pattern ◽  
Similar Pattern ◽  
Main Chain ◽  
Three Dimensional ◽  
Side Chains ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthetic Rubber

Abstract Sebrell and Dinsmore (India Rubber World 103, 37 (1944); Rubber Chem. Tech. 16, 857 (1943)) found that the x-ray diffraction pattern of Buna-S consists of a broad halo similar to that obtained with liquids. This type of pattern was obtained whether the Buna-S was unstretched or stretched. Unstretched natural rubber gives a similar pattern, but stretched natural rubber gives a characteristic fiber pattern. This fiber pattern demonstrates the existence of three-dimensional crystallites. Buna-S would not be expected to yield a fiber diagram while stretched because the molecules of this synthetic rubber are probably not constructed in a regular fashion. The styrene residues are presumably distributed at random along the length of the molecule, and there may be side-chains which branch off the main chain. However, when considerably stretched, a Buna-S vulcanizate would be expected to exhibit some indication in its x-ray diagram that alignment of the molecules has occurred.

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