Relationships between Chemical Structures of Crosslink Sites and Physical Properties of Vulcanized Rubbers. Part V. Analysis of Chemical Structures of Combined Sulfur in Crosslink Sites for Various EPDM Vulcanizates

1970 ◽  
Vol 43 (2) ◽  
pp. 424-430 ◽  
Author(s):  
M. Imoto ◽  
Y. Minoura ◽  
K. Goto ◽  
H. Harada ◽  
K. Nishihira ◽  
...  
Keyword(s):  
Physical Properties ◽  
Chemical Structure ◽  
Model Compounds ◽  
Chemical Structures ◽  
Curing Agents

Abstract Various EPDM vulcanizates with different chemical structures of crosslink sites, such as C—C, C—R—C and C—Sz—C linkage, were obtained by using a variety of curing agents. C—Sz—C linkage was separated into polysulfide linkage and monosulfide linkage by using the LiAlH4 method which was confirmed beforehand with model compounds. The relationships between the chemical structure of combined sulfur in the crosslink sites and the type of curing agents used were clarified. For example, the mole ratios of polysulfide linkage to all the combined sulfurs in the vulcanizates by using DCP—S8, TMTD, S8—TMTD and S8-zinc dimethyldithiocarbamate curing system were respectively 0.35, 0.25, 0.53 and 0.82 at 160° C for 45 minutes. But in DCP—S8 curing system considerable C—C linkages seemed to be formed in addition to the C—Sz—C linkage.

scholarly journals On Face Index of Silicon Carbides

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Xiujun Zhang ◽  
Ali Raza ◽  
Asfand Fahad ◽  
Muhammad Kamran Jamil ◽  
Muhammad Anwar Chaudhry ◽  
...  
Keyword(s):  
Physical Properties ◽  
Computer Networks ◽  
Chemical Structure ◽  
Topological Indices ◽  
Graph Invariant ◽  
Graph Invariants ◽  
Chemical Structures ◽  
Boiling Points ◽  
Silicon Carbides ◽  
The Face

Several graph invariants have been defined and studied, which present applications in nanochemistry, computer networks, and other areas of science. One vastly studied class of the graph invariants is the class of the topological indices, which helps in the studies of chemical, biological, and physical properties of a chemical structure. One recently introduced graph invariant is the face index, which can assist in predicting the energy and the boiling points of the certain chemical structures. In this paper, we drive the analytical closed formulas of face index of silicon carbides Si2C3−Ia,b, Si2C3−IIa,b, Si2C3−IIIa,b, and SiC3−IIIa,b.

scholarly journals Chemical structure and physical properties of diamond-like amorphous carbon films prepared by magnetron sputtering

1990 ◽  
Vol 5 (11) ◽  
pp. 2543-2554 ◽  
Author(s):  
N-H. Cho ◽  
K. M. Krishnan ◽  
D. K. Veirs ◽  
M. D. Rubin ◽  
C. B. Hopper ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Magnetron Sputtering ◽  
Physical Properties ◽  
Band Gap ◽  
Amorphous Carbon ◽  
Chemical Structure ◽  
Optical Band Gap ◽  
Mass Density ◽  
Carbon Films ◽  
Chemical Structures

Thin films of amorphous carbon (a–C) and amorphous hydrogenated carbon (a–C:H) were prepared using magnetron sputtering of a graphite target. The chemical structures of the films were characterized using electron energy loss spectroscopy (EELS) and Raman spectroscopy. The mass density, hardness, residual stress, optical band gap, and electrical resistivity were determined, and their relation to the film's chemical structure are discussed. It was found that the graphitic component increases with increasing sputtering power density. This is accompanied by a decrease in the electrical resistivity, optical band gap, mass density, and hardness. Increasing the hydrogen content in the sputtering gas mixture results in decreasing hardness (14 GPa to 3 GPa) and mass density, and increasing optical band gap and electrical resistivity. The variation in the physical properties and chemical structures of these films can be explained in terms of the changes in the volume of sp2-bonded clusters in the a–C films and changes in the termination of the graphitic clusters and sp3-bonded networks by hydrogen in the a–C:H films.

Chemical structure of diamond-like carbon thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 710-711
Author(s):  
N.-H. Cho ◽  
K.M. Krishnan ◽  
D.B. Bogy
Keyword(s):  
Electrical Resistivity ◽  
Chemical Structure ◽  
Diamond Like Carbon ◽  
Chemical Structures ◽  
Sputtering Power ◽  
Data Aquisition ◽  
Equilibrium Phases ◽  
Electron Energy Loss ◽  
Power Densities ◽  
Preparation Techniques

Diamond-like carbon (DLC) films have attracted much attention due to their useful properties and applications. These properties are quite variable depending on film preparation techniques and conditions, DLC is a metastable state formed from highly non-equilibrium phases during the condensation of ionized particles. The nature of the films is therefore strongly dependent on their particular chemical structures. In this study, electron energy loss spectroscopy (EELS) was used to investigate how the chemical bonding configurations of DLC films vary as a function of sputtering power densities. The electrical resistivity of the films was determined, and related to their chemical structure.DLC films with a thickness of about 300Å were prepared at 0.1, 1.1, 2.1, and 10.0 watts/cm2, respectively, on NaCl substrates by d.c. magnetron sputtering. EEL spectra were obtained from diamond, graphite, and the films using a JEOL 200 CX electron microscope operating at 200 kV. A Gatan parallel EEL spectrometer and a Kevex data aquisition system were used to analyze the energy distribution of transmitted electrons. The electrical resistivity of the films was measured by the four point probe method.

scholarly journals A Further Comprehensive Review on the Phytoconstituents from the Genus Erythrina

2020 ◽  
Vol 23 (1) ◽  
pp. 65-77 ◽  
Author(s):  
Mohammad Musarraf Hussain
Keyword(s):  
Chemical Structure ◽  
Biological Activities ◽  
Chemical Constituents ◽  
Pharmaceutical Journal ◽  
Significant Source ◽  
Comprehensive Review ◽  
Chemical Structures ◽  
Previous Review

Erythrina is a significant source of phytoconstituents. The aim of this review is to solicitude of classification, synthesis, and phytochemicals with biological activities of Erythrina. In our previous review on this genus (Hussain et. al., 2016a) fifteen species (Erythrina addisoniae, E. caribeae, E. indica, E. lattisima, E. melanacantha, E. mildbraedii, E. poeppigiama, E. stricta, E. subumbrans, E. veriagata, E. vespertilio, E. velutina, E. zeberi, E. zeyheri and E. americana) have been studied and 155 molecules with chemical structures were reported. A further comprehensive review was done upon continuation on the same genus and thirteen species (E. abyssinica, E. arborescens, E. berteroana, E. burttii, E. caffra, E. coralloids, E. crista-galli, E. fusca, E. herbaceae, E. lysistemon, E. mulungu, E. speciosa and E. tahitensis) of Erythrina have been studied and 127 compounds are reported as phytoconstituents with their chemical structure in this review. Erythrina crista-galli and E. lysistemon consist of highest number of chemical constituents. Bangladesh Pharmaceutical Journal 23(1): 65-77, 2020

Effects of physical and chemical structures of bacterial cellulose on its enhancement to paper physical properties

Cellulose ◽  
2017 ◽  
Vol 24 (8) ◽  
pp. 3513-3523 ◽  
Author(s):  
Zhouyang Xiang ◽  
Qingguo Liu ◽  
Yong Chen ◽  
Fachuang Lu
Keyword(s):  
Physical Properties ◽  
Bacterial Cellulose ◽  
Chemical Structures ◽  
Physical And Chemical

Physical Properties and Chemical Structure of High-Amylose Corn Starch Fractions

1964 ◽  
Vol 16 (11) ◽  
pp. 345-351 ◽  
Author(s):  
Edna M. Montgomery ◽  
K. R. Sexson ◽  
R. J. Dimler ◽  
F. R. Senti
Keyword(s):  
Physical Properties ◽  
Chemical Structure ◽  
Corn Starch ◽  
High Amylose

scholarly journals A Review of Bacteriochlorophyllides: Chemical Structures and Applications

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1293
Author(s):  
Chih-Hui Yang ◽  
Keng-Shiang Huang ◽  
Yi-Ting Wang ◽  
Jei-Fu Shaw
Keyword(s):  
Solar Cell ◽  
Energy Harvesting ◽  
Chemical Structure ◽  
The Other ◽  
Dye Sensitized Solar Cell ◽  
Synthetic Route ◽  
Chemical Structures ◽  
Dye Sensitized ◽  
Heme Synthesis ◽  
Potential Applications

Generally, bacteriochlorophyllides were responsible for the photosynthesis in bacteria. Seven types of bacteriochlorophyllides have been disclosed. Bacteriochlorophyllides a/b/g could be synthesized from divinyl chlorophyllide a. The other bacteriochlorophyllides c/d/e/f could be synthesized from chlorophyllide a. The chemical structure and synthetic route of bacteriochlorophyllides were summarized in this review. Furthermore, the potential applications of bacteriochlorophyllides in photosensitizers, immunosensors, influence on bacteriochlorophyll aggregation, dye-sensitized solar cell, heme synthesis and for light energy harvesting simulation were discussed.

scholarly journals Brazilian gutta-percha points. Part II: thermal properties

2007 ◽  
Vol 21 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Cláudio Maniglia-Ferreira ◽  
Eduardo Diogo Gurgel-Filho ◽  
João Batista Araújo Silva Jr ◽  
Regina Célia Monteiro de Paula ◽  
Judith Pessoa Andrade Feitosa ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Physical Properties ◽  
Ambient Temperature ◽  
Amorphous Phase ◽  
Thermal Behaviour ◽  
Chemical Structure ◽  
Scanning Calorimetry ◽  
Gutta Percha ◽  
Thermal Manipulation

This study was undertaken to explore the effect of heating on gutta-percha, analyzing the occurrence of endothermic peaks corresponding to the transformation that occurs in the crystalline structure of the polymer during thermal manipulation. This study also seeked to determine the temperature at which these peaks occur, causing a transformation from the beta- to the alpha-form, and from the alpha- to the amorphous phase. Eight nonstandardized gutta-percha points commercially available in Brazil (Konne, Tanari, Endopoint, Odous, Dentsply 0.04, Dentsply 0.06, Dentsply TP, Dentsply FM) and pure gutta-percha (control) were analysed using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The transition temperatures were determined and analysed. With the exception of Dentsply 0.04 and Dentsply 0.06, the majority of the products showed thermal behaviour typical of beta-gutta-percha, with two endothermic peaks, exhibiting two crystalline transformations upon heating from ambient temperature to 130°. Upon cooling and reheating, few samples presented two endothermic peaks. It was concluded that heating dental gutta-percha to 130°C causes changes to its chemical structure which permanently alter its physical properties.

scholarly journals Competitive cocrystallization and its application in the separation of flavonoids

IUCrJ ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 195-207
Author(s):  
Yanming Xia ◽  
Yuanfeng Wei ◽  
Hui Chen ◽  
Shuai Qian ◽  
Jianjun Zhang ◽  
...  
Keyword(s):  
Free Energy ◽  
Formation Constant ◽  
Energy Gap ◽  
Hirshfeld Surface ◽  
Methanol Solution ◽  
Model Compounds ◽  
Electronic Density ◽  
Chemical Structures ◽  
Similar Chemical ◽  
Interaction Contribution

Recently, cocrystallization has been widely employed to tailor physicochemical properties of drugs in the pharmaceutical field. In this study, cocrystallization was applied to separate natural compounds with similar structures. Three flavonoids [baicalein (BAI), quercetin (QUE) and myricetin (MYR)] were used as model compounds. The coformer caffeine (CAF) could form cocrystals with all three flavonoids, namely BAI–CAF (cocrystal 1), QUE–CAF (cocrystal 2) and MYR–CAF (cocrystal 3). After adding CAF to methanol solution containing MYR and QUE (or QUE and BAI), cocrystal 3 (or cocrystal 2) preferentially formed rather than cocrystal 2 (or cocrystal 1), indicating that flavonoid separation could be achieved by competitive cocrystallization. After co-mixing the slurry of two flavonoids with CAF followed by centrifugation, the resolution ratio that could be achieved was 70–80% with purity >90%. Among the three cocrystals, cocrystal 3 showed the lowest formation constant with a negative Gibbs free energy of nucleation and the highest energy gap. Hirshfeld surface analysis and density of states analysis found that cocrystal 3 had the highest strong interaction contribution and the closest electronic density, respectively, followed by cocrystal 2 and cocrystal 1, suggesting CAF could competitively form a cocrystal with MYR much more easily than QUE and BAI. Cocrystallization is a promising approach for green and effective separation of natural products with similar chemical structures.

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