Polymerization Phenomena in the Vulcanization Process

1954 ◽  
Vol 27 (4) ◽  
pp. 920-924 ◽  
Author(s):  
B. Dogadkin ◽  
M. Feldstein ◽  
A. Dobromyslova ◽  
V. Shkurina ◽  
M. Kalpunov
Keyword(s):  
Spectral Analysis ◽  
Free Radicals ◽  
Hydrogen Bonds ◽  
Functional Groups ◽  
Chemical Reaction ◽  
Van Der Waals ◽  
Chemical Bonds ◽  
Polarization Orientation ◽  
Vulcanization Process

Abstract According to theories developed by the authors, vulcanization consists essentially in the formation of local chemical van der Waals bonds (polarization, orientation bonds) and hydrogen bonds between the molecular chains of rubber. These bonds are formed as a result of the chemical reaction of the rubber with the vulcanizing agent, oxygen, and accelerators, and with other components of the vulcanizing system which contain functional groups. The essential type of chemical bonds consists of atomic groups of the vulcanizing agent (in the case of sulfur vulcanizates, “bridge” sulfur). Hypotheses were advanced concerning the course during vulcanization of the polymerization processes, initiated by the free radicals which are formed by the vulcanizing agent, and leading to the formation of —C — C—bonds between the molecular chains of the rubber. However, no proof of the existence of such processes has been obtained ; furthermore, certain data, for example, data obtained by spectral analysis, contradict such an assumption. The present paper is devoted to a description of experiments which show the existence of polymerization processes involving free radicals in vulcanized systems which contain accelerators of the disulfide and sulfenamide type.

The reaction of free radicals and functional groups during coal oxidation at low temperature under different oxygen concentrations

2021 ◽  
Vol 150 ◽  
pp. 148-156
Author(s):  
Buzhuang Zhou ◽  
Shengqiang Yang ◽  
Xiaoyuan Jiang ◽  
Jiawen Cai ◽  
Qin Xu ◽  
...  
Keyword(s):  
Free Radicals ◽  
Low Temperature ◽  
Functional Groups ◽  
Coal Oxidation ◽  
Oxygen Concentrations

Mechanochemical Phenomena in Polymers. II. The Effects of Initiators and Inhibitors of Chain Processes

1963 ◽  
Vol 36 (2) ◽  
pp. 480-487
Author(s):  
E. V. Reztsova ◽  
B. T. Kipkina ◽  
G. L. Slonimskii
Keyword(s):  
Free Radicals ◽  
Fatigue Resistance ◽  
Substantial Effect ◽  
Chemical Bonds ◽  
Chain Processes ◽  
Radical Processes ◽  
Effect Of Inhibitors ◽  
Dynamic Fatigue

Abstract 1. The substantial effect of inhibitors and initiators of chain radical processes on the change in the properties of rubbers in milling, as well as on the resistance of vulcanizates to fatigue, has been shown. This indicates a mechanochemical mechanism for processing of polymers and in the fatigue of elastomers. The act of mechanical scission of chemical bonds, with the formation of free radicals which initiate the secondary chain processes, rests on these processes. 2. The possibility has been shown of regulating the properties of polymers during processing, and also of increasing the dynamic fatigue resistance of vulcanizates by incorporating small quantities of additives active in regard to free radicals.

scholarly journals N′-Cyclododecylidenepyridine-4-carbohydrazide

2012 ◽  
Vol 68 (4) ◽  
pp. o1205-o1205
Author(s):  
Andreas Lemmerer ◽  
Joel Bernstein ◽  
Volker Kahlenberg
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Functional Groups ◽  
Title Compound ◽  
Antituberculosis Drug ◽  
Compound C

The title compound, C18H27N3O, is a derivative of the antituberculosis drug isoniazid (systematic name: pyridine-4-carbohydrazidei). The crystal structure consists of repeatingC(4) chains along thebaxis, formed by N—H...O hydrogen bonds with adjacent amide functional groups that are related by ab-glide plane. The cyclododecyl ring has the same approximately `square' conformation, as seen in the parent hydrocarbon cyclododecane.

Tetrakis[(1-phenyltetrazol-5-yl)sulfanylmethyl]methane

2007 ◽  
Vol 63 (3) ◽  
pp. o1145-o1147 ◽  
Author(s):  
Alexander S. Lyakhov ◽  
Marina V. Zatsepina ◽  
Tatiana V. Artamonova ◽  
Pavel N. Gaponik ◽  
Grigorii I. Koldobskii
Keyword(s):  
Hydrogen Bonds ◽  
Title Compound ◽  
Rotation Axis ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Π Interactions ◽  
Compound C

The title compound, C33H28N16S4, prepared by the divergent method, presents a core unit for further synthesis of tetrazole-containing dendrimers. The central C atom lies on a crystallographic twofold rotation axis. π–π Interactions and weak non-classical C—H...N hydrogen bonds are responsible for the formation of layers parallel to the bc plane, with van der Waals interactions between them.

scholarly journals Manganese Fluorene Phosphonates: Formation of Isolated Chains

Inorganics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 92 ◽  
Author(s):  
Clarisse Bloyet ◽  
Jean-Michel Rueff ◽  
Vincent Caignaert ◽  
Bernard Raveau ◽  
Jean-François Lohier ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Hydrogen Bonds ◽  
Phosphonic Acid ◽  
Van Der Waals ◽  
Exchange Interactions ◽  
Van Der Waals Interactions ◽  
Antiferromagnetic Exchange ◽  
Hydrothermal Conditions ◽  
Hirshfeld Surfaces ◽  
Nitrate Tetrahydrate

9,9-dimethylfluorenyl-2-phosphonic acid 1 was reacted with manganese nitrate tetrahydrate to produce under hydrothermal conditions the crystalline manganese phosphonate Mn(H2O)2[O2(OH)PC15H13]2·2H2O which crystallize in the P21/c space group. This compound is a rare example of Mn-phosphonate material featuring isolated chains. The interactions between these chains containing the 9,9-dimethylfluorenyl moieties, result from Van der Waals interactions involving the fluorene ligands and C···H–C hydrogen bonds as revealed by Hirshfeld Surfaces. This material features antiferromagnetic exchange interactions as revealed by the magnetic susceptibility as a function of the temperature.

scholarly journals Crystal structures of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(pentafluorophenyl)porphyrin as the chloroform monosolvate and tetrahydrofuran monosolvate

2020 ◽  
Vol 76 (2) ◽  
pp. 214-220
Author(s):  
Christopher J. Kingsbury ◽  
Keith J. Flanagan ◽  
Marc Kielmann ◽  
Brendan Twamley ◽  
Mathias O. Senge
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Van Der Waals ◽  
Supramolecular Interactions ◽  
Porphyrin Ring ◽  
Similar Conformation

The crystal structures of the title compounds, two solvates (CHCl3 and THF) of a symmetric and highly substituted porphyrin, C44H2Br8F20N4 or OBrTPFPP, are described. These structures each feature a non-planar porphyrin ring, exhibiting a similar conformation of the strained ring independent of solvent identity. These distorted porphyrins are able to form hydrogen bonds and sub-van der Waals halogen interactions with enclathrated solvent; supramolecular interactions of proximal macrocycles are additionally affected by solvent choice. The crystal studied for compound 1·CHCl3 was refined as an inversion twin. One pentafluorophenyl group was modelled as disordered over two sites [occupancy ratio = 0.462 (7):0.538 (7)]. The chloroform solvate was also modelled as disordered over two orientations [occupancy ratio = 0.882 (7): 0.118 (7).

scholarly journals 2,4-Dibromo-2,3-dihydro-1H-inden-1-yl acetate

2012 ◽  
Vol 68 (6) ◽  
pp. o1884-o1884 ◽  
Author(s):  
Ísmail Çelik ◽  
Mehmet Akkurt ◽  
Makbule Yilmaz ◽  
Ahmet Tutar ◽  
Ramazan Erenler ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Stacking Interactions ◽  
Compound C ◽  
Centroid Distance ◽  
Cyclopentene Ring

In the title compound, C11H10Br2O2, the cyclopentene ring fused to the benzene ring adopts an envelope conformation, with the C atom attached to the Br atom as the flap. The crystal structure does not exhibit any classical hydrogen bonds. The molecular packing is stabilized by van der Waals forces and π–π stacking interactions with a centroid–centroid distance of 3.811 (4) Å.

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