Action of Light on Sodium-Butadiene Rubber

1952 ◽  
Vol 25 (4) ◽  
pp. 872-877 ◽  
Author(s):  
A. F. Postovskaya ◽  
A. S. Kuzminskiĭ
Keyword(s):  
Free Radicals ◽  
Quantum Yield ◽  
High Vacuum ◽  
Experimental Methods ◽  
Carbon Chain ◽  
Small Degree ◽  
Butadiene Rubber ◽  
Gaseous Products ◽  
Gas Formation ◽  
Small Quantum

Abstract An apparatus was devised and experimental methods of investigating the action of light on polymers in a high vacuum (10™6 mm. of mercury) were developed. The limits of accuracy of the methods for measuring gas formation and decrease of unsaturation are 1–2 per cent. The effect of ultraviolet radiation on sodium-butadiene rubber in a high vacuum is the formation of gaseous byproducts. The latter appear as two fractions: one which condenses at 180° C, and one which does not condense under the same conditions. The noncondensing part comprised 84 per cent of the total, and consisted of 64 per cent hydrogen and 32 per cent methane; this indicates rupture of the —C—C— and —C—H bonds. The action of light on rubber is accompanied by a loss of unsaturation. The change of unsaturation is primarily in the main chains and only to a small degree in the side chains (we know that the reverse is true with respect to the effect of heat). Measurements were made of the light energy absorbed by rubber, and the quantum yield of gaseous products was calculated. The small quantum yield (2×10−3) indicates the incatenate nature of the process. The decrease of solubility of an irradiated polymer is a consequence of a reaction between free radicals forming after rupture of the —C—H bond, and also after rupture of the carbon chain.

Controlling the magic size of white light-emitting CdSe quantum dots

Nanoscale ◽  
2018 ◽  
Vol 10 (21) ◽  
pp. 10256-10261 ◽  
Author(s):  
Sheng Dai ◽  
Yu-Sheng Su ◽  
Shu-Ru Chung ◽  
Kuan-Wen Wang ◽  
Xiaoqing Pan
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
White Light ◽  
Carbon Chain ◽  
Cdse Quantum Dots ◽  
Light Emitting

By employing a particular non-coordinating solvent and long carbon chain amine, white-light emitting CdSe quantum dots with magic sizes and enhanced quantum yield can be prepared.

Effects of Electromagnetic Fields on the Quantum Yield of Free Radicals in Cryptochrome

2019 ◽  
Vol 953 ◽  
pp. 127-132
Author(s):  
Yu Ling Chen ◽  
Du Yan Geng ◽  
Chuan Fang Chen
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Free Radicals ◽  
Free Radical ◽  
Quantum Yield ◽  
Electromagnetic Fields ◽  
Applied Magnetic Field ◽  
Geomagnetic Field ◽  
Quantum Biology ◽  
The Magnetic Field

In this paper, the effects of the quantum yield of free radicals in cryptochrome exposed to different electromagnetic fields were studied through the quantum biology. The results showed that the spikes characteristics was produced in the free radicals in cryptochrome, when it exposed to the applied magnetic field (ω = 50 Hz, B0 = 50 μT). The spikes produced by the electromagnetic field was independent of the changes of polar θ. When the frequency of the magnetic field increased, the spikes characteristics produced in unit time also increased. These results showed that the environmental electromagnetic field could affect the response of organisms to the geomagnetic field by influencing the quantum yield in the mechanism of free radical pair.It provided a basis for studying the influence of environmental electromagnetic field on biology, especially the navigation of biological magnetism.

The Effect of Waxes on Rubber Vulcanisates

2005 ◽  
Vol 21 (2) ◽  
pp. 139-153 ◽  
Author(s):  
S.L. Agrawal ◽  
S. Mandot ◽  
S. Bandyopadhyay ◽  
R. Mukhopadhyay ◽  
A.S. Deuri
Keyword(s):  
Surface Layer ◽  
Natural Rubber ◽  
Carbon Chain ◽  
Competitive Market ◽  
Butadiene Rubber ◽  
Dynamic Conditions

Certain substances like wax, when incorporated into rubber vulcanisates during mixing prior to vulcanisation are able to bloom and form a surface layer with significant importance in appearance and in protection against ozone. In tyres, this is particularly important in sidewall compounds as ozone protection reflects in its storage, both under static and dynamic conditions, and appearance plays an important role in determining acceptance in today‘s competitive market. In this paper, the effect of different waxes and their blends on the properties of sidewall compounds with varying natural rubber/butadiene rubber ratios, is reported. It was found that blends of paraffin and microcrystalline waxes with specific carbon chain distributions resulted in optimum properties.

Untersuchung von einfachen π-Elektronensystemen mit Hilfe von Elektronenspin-Resonanz und Polarographie

1965 ◽  
Vol 20 (9) ◽  
pp. 1093-1102
Author(s):  
K. Möbius
Keyword(s):  
Free Radicals ◽  
Simple Model ◽  
Molecular Orbital ◽  
Linear Correlation ◽  
Experimental Methods ◽  
Subsequent Paper ◽  
G Factor ◽  
Experimental Part ◽  
Theoretical Part ◽  
G Factors

It was the intention of this study to test the molecular orbital approximations of HÜCKEL and McLACHLAN by means of the experimental methods of EPR and polarography. In the experimental part problems are discussed as to electrolytic generation of free radicals and as to the ERP method with g-factors being measured with an accuracy of ± 2 ppm. In the theoretical part the molecular orbital theories of HÜCKEL and MCLACHLAN are summerized with particular regard to quantities which can be measured by EPR and polarography. A simple model of a σ → π → σ* excitation is developed which predicts a linear correlation between g-factor shift and π-energy of the lowest half-filled orbital. The validity of the model is discussed in terms of the g-factor theory recently deduced by STONE. The results of the experiments are presented in a subsequent paper.

Ultrafast Photoisomerization in Anabaena Sensory Rhodopsin: High Speed but Small Quantum Yield

2016 ◽  
Author(s):  
Damianos Agathangelou ◽  
Alexandre Cheminal ◽  
Jeremie Leonard ◽  
Hideki Kandori ◽  
Kwan-Hwang Jung ◽  
...  
Keyword(s):  
Quantum Yield ◽  
High Speed ◽  
Sensory Rhodopsin ◽  
Small Quantum

Molecular Structure of Styrene-Butadiene Copolymers. Dynamic Mechanical Measurements

1951 ◽  
Vol 24 (3) ◽  
pp. 574-584 ◽  
Author(s):  
L. E. Nielsen ◽  
Rolf Buchdahl ◽  
G. C. Claver
Keyword(s):  
Experimental Methods ◽  
Dynamic Shear Modulus ◽  
Butadiene Rubber ◽  
Dynamic Shear ◽  
Swelling Properties ◽  
Mechanical Measurements ◽  
Mechanical Damping ◽  
Styrene Butadiene ◽  
Damping Peak ◽  
Polymerization Conditions

Abstract The dynamic shear modulus, mechanical damping, swelling properties in benzene, and infrared spectra have been determined on a series of styrene-butadiene copolymers which were prepared under a variety of polymerization conditions. Evidence is presented which indicates it may be possible to prepare a poly-butadiene rubber which retains its rubberlike properties down to −120° C. Materials of the same overall composition were often found to differ greatly in structure as determined by these experimental methods. Many of these differences can be explained in terms of various types of heterogeneity found in the copolymers. The temperature of maximum mechanical damping is primarily determined by the composition of the copolymer, whereas the width of the damping peak is related to the heterogeneity of the material. The work reported here is part of an investigation of the differences in physical properaties of polymers of like composition that occur as a result of changes in polymerization conditions.

scholarly journals Solid-Phase Thermal Decomposition of 2,4-Dinitroimidazole (2,4-DNI)

1995 ◽  
Vol 418 ◽  
Author(s):  
Leanna Minier ◽  
Richard Behrens ◽  
Suryanarayana Bulusu
Keyword(s):  
Thermal Decomposition ◽  
Induction Period ◽  
Solid Phase ◽  
Low Molecular Weight ◽  
Ftir Analysis ◽  
Pyrolysis Products ◽  
Gaseous Products ◽  
Elemental Formula ◽  
Gas Formation ◽  
Primary Products

AbstractThe solid-phase thermal decomposition of the insensitive energetic aromatic heterocycle 2,4- dinitroimidazole (2,4-DNI: mp 265–274°C) is studied utilizing simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) between 200° and 247°C. The pyrolysis products have been identified using perdeuterated and N-labeled isotopomers. The products consist of low molecular-weight gases and a thermally stable solid residue. The major gaseous products are NO, CO2, CO, N2, HNCO and H2O. Minor gaseous products are HCN, C2N2, NO2, C3H4N2, C3H3N3O and NH3. The elemental formula of the residue is C2HN2O and FTIR analysis suggests that it is polyurea- and polycarbamate-like in nature. The rates of formation of the gaseous products and their respective quantities have been determined for a typical isothermal decomposition experiment at 235°C. The temporal behaviors of the gas formation rates indicate that the overall decomposition is characterized by a sequence of four events; 1) an early decomposition period induced by impurities and H2O, 2) an induction period where CO2 and NO are the primary products formed at relatively constant rates, 3) an autoacceleratory period that peaks when the sample is depleted and 4) a final period in which the residue decomposes. Arrhenius parameters for the induction period are Ea = 46.9 ± 0.7 kcal/mol and Log(A) = 16.3 ± 0.3. Decomposition pathways that are consistent with the data are presented.

scholarly journals Effects of calcium on the evolution of nitrogen during pyrolysis of a typical low rank coal

2019 ◽  
Vol 7 (2) ◽  
pp. 397-404
Author(s):  
Xiongchao Lin ◽  
Sasha Yang ◽  
Xujun Chen ◽  
Panpan Zheng ◽  
Yonggang Wang ◽  
...  
Keyword(s):  
Free Radicals ◽  
Pyrolysis Temperature ◽  
Low Rank ◽  
Mineral Matter ◽  
Condensation Polymerization ◽  
Coal Pyrolysis ◽  
Decomposition Reactions ◽  
Gaseous Products ◽  
Secondary Reactions ◽  
Different Temperatures

AbstractThis study aims to investigate the effects of calcium on the migration of nitrogen in coal (coal-N) to N-containing gas species, particularly, NH3 and HCN (volatile-N) in volatiles, as well as the chemical transformation of the N in char during coal pyrolysis under different temperatures. The pyrolysis experiments of Shengli brown coal and its derived coal samples loaded with different contents of calcium were conducted under 600–800 °C in a novel fluidized bed reactor. The experimental results showed that during coal pyrolysis, the generation of NH3 is mainly derived from secondary reactions among volatiles, tar and char with the catalytic effect of mineral matter, especially calcium in coal. Increasing pyrolysis temperature from 600 to 800 °C could enhance the release of N in coal to volatiles. Meanwhile, the increased pyrolysis temperature could also inhibit the generation of NH3 while facilitating the formation of HCN. The release of HCN is more sensitive to pyrolysis temperatures. Specifically, under higher pyrolysis temperatures, more N-containing structures in coal would become thermally unstable and crack into HCN; On the other hand, higher pyrolysis temperature could also enhance the decomposition of N in coal to N-containing species in tar or N2, thus reducing the release of HCN and NH3. Nitrogen in tar could either undergo secondary decomposition reactions, generating NH3, HCN, N2 and other N-containing species in gas phase, or experience condensation polymerization by forming macromolecular structure and be retained in char at high pyrolysis temperatures. Calcium could significantly restrain the release of N from coal, thus reducing the yields of NH3 and HCN. During coal pyrolysis, calcium catalytically enhances the fracture and combination of chemical bonds, generating abundant free radicals. These free radicals could continuously attack N-containing structures and consequently release the N-containing gaseous products, such as NH3, HCN, N2 etc., resulting in the decrease of N in char. Calcium also plays important roles in nitrogen transformation in char during coal pyrolysis by catalytically intensifying the transformation of N in char from pyridinic nitrogen (N-6) and pyrrolic nitrogen (N-5) to quaternary type nitrogen (N-Q) during coal pyrolysis.

Sulfur and peroxide curing of rubber magnetic composites with the application of zinc methacrylate

2020 ◽  
pp. 009524432091562
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničaková ◽  
Rastislav Dosoudil ◽  
Katarína Tomanová ◽  
Ivan Hudec ◽  
...  
Keyword(s):  
Free Radicals ◽  
Organic Peroxide ◽  
Butadiene Rubber ◽  
Magnetic Composites ◽  
Curing Characteristics ◽  
Peroxide Decomposition ◽  
Peroxide Curing ◽  
Link Density ◽  
Strong Adhesion ◽  
Cross Link Density

Rubber magnetic composites based on acrylonitrile butadiene rubber and strontium ferrite were cured with standard sulfur-based vulcanization systems as well as an organic peroxide. Zinc methacrylate (ZDMA) as a coagent was applied in both sulfur and peroxide vulcanization of rubber magnets. The aim was to evaluate the influence of ZDMA on curing characteristics and cross-link density of the prepared materials. Subsequently, physical-mechanical and magnetic properties were investigated. The results showed that ZDMA takes an active part in the cross-linking process of composites cured with an organic peroxide. Due to the presence of free radicals formed from peroxide decomposition, molecules of ZDMA polymerize into the nanostructures which can be physically adsorbed or chemically grafted onto rubber chains. Moreover, owing to zinc ions, ZDMA exhibits strong adhesion to ferrite filler and thus it contributes to the improvement of adhesion between the rubber and the filler on the interphase. The overall reinforcement of rubber magnetic composites was subsequently achieved. In the case of rubber magnets cured with the sulfur-based system, ZDMA acts as a conventional filler with a slight reinforcing effect due to the lack of free radicals required for its polymerization.

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