Effect of Molecular Weight, Shape of the Molecule, and Presence of Polar Groups on the Autohesion of High Polymers. III

1957 ◽  
Vol 30 (2) ◽  
pp. 548-554 ◽  
Author(s):  
S. S. Voyutskiĭ ◽  
B. V. Shtarkh
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Temperature Dependence ◽  
Structural Changes ◽  
Chain Molecule ◽  
Complete Disappearance ◽  
Short Side ◽  
Polar Groups ◽  
Kinetics Of ◽  
High Polymers

Abstract 1. It is shown for polyisobutylenes of different molecular weight that increase in the size of the chain molecule retards autohesion, but increases the limiting value to which the work of autohesion tends with increasing contact time. 2. Investigation of the temperature dependence of autohesion of polyisobutylenes showed that the activation energy does not depend on the molecular weight of the polyisobutylene. 3. It is shown for polybutadienes with varying contents of 1,4- and 1,2-structures that autohesion decreases with increase in the number of short side groups in the molecule, which apparently hinder diffusion by purely steric causes. 4. Investigation of the temperature dependence of autohesion of butadienenitrile copolymers with different contents of acrylonitrile in the molecule showed that the activation energy of autohesion increases with increase of polar nitrile groups in the polymer. 5. It is shown for the vulcanization of natural rubber that the formation of a spatial structure results in complete disappearance of autohesion in high polymers. It is shown that the kinetics of changes of autohesion during vulcanization can effectively characterize the structural changes which take place in the polymer during the process.

Adhesion of High Polymers. 3. Effects of the Size, Shape, and Polarity on Adhesion to Cellophane

1958 ◽  
Vol 31 (4) ◽  
pp. 712-718
Author(s):  
S. S. Voyutskiĭ ◽  
A. I. Shapovalova ◽  
A. P. Pisarenko
Keyword(s):  
Molecular Weight ◽  
Bond Strength ◽  
Diffusion Theory ◽  
Polymer Molecule ◽  
High Polymer ◽  
Short Side ◽  
Polymer Adhesion ◽  
Polar Groups ◽  
Cohesive Properties ◽  
High Polymers

Abstract 1. The method developed by the authors has been used to study the influence of size, form, and polarity of macromolecules on the adhesion of high polymers to cellophane. 2. Adhesion of high polymers to cellophane increases with decreasing molecular weight. However, for maximum bond strength, the cohesive properties of the polymer must also be taken into account. 3. Increase of the number of short side chains in the polymer molecule lowers its adhesion. 4. The adhesion of a polymer to cellophane decreases with increasing contents of polar groups in its macromolecules. 5. The results are explained on the basis of the diffusion theory of high polymer adhesion developed by the authors.

scholarly journals Транспортные процессы с участием атомов углерода между поверхностью и объемом родия при образовании и разрушении графена

2020 ◽  
Vol 54 (6) ◽  
pp. 552
Author(s):  
Е.В. Рутьков ◽  
Е.Ю. Афанасьева ◽  
Н.Р. Галль
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Temperature Dependence ◽  
Atomic Carbon ◽  
Graphene Growth ◽  
Carbon Dissolution ◽  
The Difference ◽  
Kinetics Of

Equilibrium transport of atomic carbon between Rh surface and bulk has been studied. This transport controls the kinetics of the phase transition resulting in graphene growth or destruction. The difference ΔE=0.7 eV has been measured between the activation energy of atomic carbon dissolution E1s and that of its segregation from the bulk to the surface E1s. The temperature dependence of chemisorbed carbon critical cover Neq = Neq(T) has been measured, that is the cover when 2D phase transition takes place and graphene islands start to grow. E.g., Neq = 7.7•1014 cm-2 at T = 1800 K, and Neq = 3.1•1014 cm-2 at T = 1000 K.

Research on Kinetics of Hydrolysis Preparation of Micro-Molecular Dextran

2013 ◽  
Vol 748 ◽  
pp. 295-298
Author(s):  
Shu Qiong Liao ◽  
Xiao Yu Peng ◽  
Xue Wang Zhang ◽  
Ke Lin Huang ◽  
Ben Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Kinetics Equation ◽  
Temperature Range ◽  
Kinetics Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

Micro-molecular dextran was prepared in sub-critical water and sub-critical Water/CO2by hydrolysis of dextran20. The obtained products were mainly characterized by GPC. The kinetics of hydrolysis of dextran20 has been studied in the temperature range of 423.15K-463.15K. It was found that the level of dextran20 hydrolysis in sub-critical water and sub-critical water/CO2was first level kinetics equation. The activation energy was also calculated. The results demonstrated that the molecular weight of micro-molecular dextran could be controlled.

The Temperature Dependence of the Atoms Co Diffusion Coefficient in Pt80Co20(111) Alloy

2007 ◽  
Vol 265 ◽  
pp. 19-23
Author(s):  
M. Vasylyev ◽  
Vitaliy A. Tinkov ◽  
Sergey I. Sidorenko ◽  
S.M. Voloshko
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Surface Segregation ◽  
Surface Region ◽  
Near Surface ◽  
Kinetics Of

The method of Ionization Spectroscopy is used to study the thermo-induced kinetics of surface segregation of the Pt80Co20(111) alloy components. The temperature dependence of the Co diffusion coefficient in this alloy is determined. It is found that the value of the activation energy for the segregation of Co atoms in the near-surface region is close to the heat of sublimation of pure Co.

Research on the Reaction of IPDI and PPG with Organo-Tin Mixed Catalyst

2012 ◽  
Vol 430-432 ◽  
pp. 399-403
Author(s):  
Yuan Wei ◽  
Shu Lin An ◽  
Su Ran Liao
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Order Equation ◽  
Polypropylene Glycol ◽  
Step Process ◽  
Mixed Catalyst ◽  
Step Growth ◽  
Step Growth Polymerization ◽  
Kinetics Of ◽  
Polymerization Conditions

The kinetics of the reaction is essential for the synthesis of polyurethane. In this study, the reaction kinetics and polymerization conditions in two-step process of isophorone diisocyante (IPDI) and polypropylene glycol (PPG) with organo-tin mixed catalyst were investigated by chemical titration. The results showed that the reaction obeyed the second-order equation of step-growth polymerization, the rate constants of IPDI and PPG reaction at 50, 60 and 70°C were 0.0161, 0.0373 and 0.0806 kg•mol-1•min-1，respectively. The activation energy obtained from the result was 74.25 kJ•mol-1. The polyurethane with number molecular weight 38721 was synthesized and was characterized by Fourier transform infrared (FTIR).

Kinetics of the thermal reactions of ethylene. Part I

1968 ◽  
Vol 46 (14) ◽  
pp. 2415-2426 ◽  
Author(s):  
M. L. Boyd ◽  
T-M. Wu ◽  
M. H. Back
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Free Radical ◽  
Induction Period ◽  
Pressure Range ◽  
Kcal Mole ◽  
Radical Chain ◽  
Thermal Reactions ◽  
Chain Polymerization ◽  
Kinetics Of

The pyrolysis of ethylene has been studied in the temperature range 500–600 °C and the pressure range 15–60 cm. The main products were ethane, propylene, butene, butadiene, and a polymer of molecular weight corresponding to C8 or higher. Small amounts of methane, butane, unsaturated C5, unsaturated C6, and benzene were also measured. Of the main products, propylene, butene, and butadiene showed an induction period, as long as several minutes at the lowest temperature. The order with respect to ethylene of ethane, propylene, and butene was close to two and the activation energy of the rates was approximately 40 kcal/mole. The results have been interpreted in terms of a free radical chain polymerization. It is suggested that the polymer formed is unstable and decomposes to yield the products for which an induction period was observed.

scholarly journals Dynamic Viscosity and Activation Energy of Wort During Fermentation and Storing

2016 ◽  
Vol 19 (1) ◽  
pp. 6-9
Author(s):  
Peter Hlaváč ◽  
Monika Božiková ◽  
Vladimír Cviklovič
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Exponential Function ◽  
Dynamic Viscosity ◽  
Structural Changes ◽  
Effect Of Temperature ◽  
Rotational Viscometer ◽  
Viscosity Measurements ◽  
Sample Resistance

This paper presents the results of wort dynamic viscosity and activation energy during fermentation. The effect of temperature and storing time on both parameters was investigated. Measurements were performed on two wort samples. The first sample was taken at the beginning of fermentation, and the second sample after three hours of fermentation. Both samples were also measured after three weeks of storing. Dynamic viscosity measurements were performed with a digital rotational viscometer Anton Paar DV-3P, the principle of which is based on the dependency of sample resistance to probe rotation. Results of measurements are shown as graphical dependencies of both analysed parameters on temperature. The temperature dependence of dynamic viscosity can be characterised by a decreasing exponential function, while in case of activation energy linear increasing characters were obtained. Longer fermentation and storing period caused a decrease in both analysed parameters, due to the structural changes in wort samples during fermentation and storing.

Microscopic versus process parameters in heavy-oil upgrading

1992 ◽  
Vol 50 (1) ◽  
pp. 366-367
Author(s):  
V.A. Munoz ◽  
R.J. Mikula ◽  
C. Payette ◽  
W.W. Lam
Keyword(s):  
Molecular Weight ◽  
Liquid Fuels ◽  
Chemical Components ◽  
Heavy Oils ◽  
Synthetic Fuels ◽  
High Hydrogen ◽  
Optical Texture ◽  
Polar Groups ◽  
Anisotropic Character ◽  
Planar Molecules

The transformation of high molecular weight components present in heavy oils into useable liquid fuels requires their decomposition by means of a variety of processes. The low molecular weight species produced recombine under controlled conditions to generate synthetic fuels. However, an important fraction undergo further recombination into higher molecular weight components, leading to the formation of coke. The optical texture of the coke can be related to its originating components. Those with high sulfur and oxygen content tend to produce cokes with small optical texture or fine mosaic, whereas compounds with relatively high hydrogen content are likely to produce large optical texture or domains. In addition, the structure of the parent chemical components, planar or nonplanar, determines the isotropic or anisotropic character of the coke. Planar molecules have a tendency to align in an approximately parallel arrangement to initiate the formation of the nematic mesophase leading to the formation of anisotropic coke. Nonplanar highly alkylated compounds and/or those rich in polar groups form isotropic coke. The aliphatic branches produce steric hindrance to alignment, whereas the polar groups participate in cross-linking reactions.

Studies on the Behavior Some Paints in Electro-insulating Fluid Based on Vegetable Esters

2018 ◽  
Vol 69 (5) ◽  
pp. 1139-1144
Author(s):  
Iosif Lingvay ◽  
Adriana Mariana Bors ◽  
Livia Carmen Ungureanu ◽  
Valerica Stanoi ◽  
Traian Rus
Keyword(s):  
Structural Changes ◽  
Oxidation Processes ◽  
High Oleic ◽  
Painting Materials ◽  
Insulating Paper ◽  
Different Types ◽  
Mechanism And Kinetics ◽  
Kinetics Of ◽  
Natural Ester

For the purpose of using three different types of painting materials for the inner protection of the transformer vats, their behavior was studied under actual conditions of operation in the transformer (thermal stress in electro-insulating fluid based on the natural ester in contact with copper for electro-technical use and electro-insulating paper). By comparing determination of the content in furans products (HPLC technique) and gases formed (by gas-chromatography) in the electro-insulating fluid (natural ester with high oleic content) thermally aged at 130 �C to 1000 hours in closed glass vessels, it have been found that the presence the investigated painting materials lead to a change in the mechanism and kinetics of the thermo-oxidation processes. These changes are supported by oxygen dissolved in oil, what leads to decrease both to gases formation CO2, CO, H2, CH4, C2H4 and C2H6) and furans products (5-HMF, 2-FOL, 2 -FAL and 2-ACF). The painting materials investigated during the heat treatment applied did not suffer any remarkable structural changes affecting their functionality in the electro-insulating fluid based on vegetable esters.

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