The Nature of the Dynamic Double Refraction of Rubber Solutions and the Shape of Rubber Molecules

1946 ◽  
Vol 19 (2) ◽  
pp. 360-384 ◽  
Author(s):  
V. Tsvetkov ◽  
A. Petrova
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Optical Constant ◽  
Linear Polymers ◽  
Double Refraction ◽  
Flowing Liquid ◽  
Elastic Effect ◽  
Molecular Weights ◽  
Synthetic Rubber ◽  
Wide Range

Abstract The work which is described in the present paper is concerned with the development of a method for measuring the double refraction of a flowing liquid, with particular attention to a study of the structure of polymers. The dependence of double refraction and of the angle of extinction on the velocity of flow of solutions of thirty samples of synthetic rubber through a wide range of velocities was studied. For linear polymers having high molecular weights, the relation: Δn=ƒ(g), shows, when represented graphically, an ascending concave curve. This relation is rectilinear for all polymers whose molecular weights lie within the usual range. In all cases investigated, the angle of extinction lay within the limits of 45° and 0°. The dynamic optical constant which characterizes the double refraction of rubber was established experimentally. This dynamic optical constant was calculated for all samples of rubbers which were studied. Three effects on the double refraction of a solution of a polymer during flow were distinguished experimentally: (1) the effect of the shape of the particles; (2) the effect of the anisotropy of the particles ; and (3) the elastic effect. The double refraction of solutions of synthetic rubbers in an electric field was investigated with a view to determining the anisotropy of the molecules of the polymers. On the basis of the experimental data it is concluded that the double refraction of a flowing rubber solution is fundamentally influenced by the effect of tension. The theory of Kuhn and the experimental data obtained in the present work were utilized to calculate the relation between the transverse and longitudinal dimensions of all the rubbers which were studied.

Modeling the Rheology of Commercial Long Chain Branched Polymer Melts

2003 ◽  
Vol 804 ◽  
Author(s):  
Seung Joon Park ◽  
Ronald G. Larson
Keyword(s):  
Experimental Data ◽  
Hierarchical Model ◽  
Polymer Melts ◽  
Quantitative Agreement ◽  
Branched Polymers ◽  
Linear Polymers ◽  
Branched Polymer ◽  
Long Chain Branching ◽  
Wide Range ◽  
Long Chain

ABSTRACTThe predictions of a general “hierarchical model” for the rheology of general mixtures of linear and branched polymers are compared to experimental data for well-defined long-chain branched polymers. For a wide range of branched polymer melts, which include star-linear blends, H-polymers, and comb polymers, the predictions of the model agree well with experimental data. We apply the hierarchical model to metallocene-catalyzed polyethylenes (mPEs), in which the branched structures are generated by a Monte Carlo method based on the known reaction kinetics. The hierarchical model captures the shape of the curves of viscoelastic moduli vs. frequency of mPEs well and predicts accurately the effect of long chain branching on the linear viscoelastic properties. The quantitative agreement of the hierarchical model prediction with experimental data of well-defined long-chain branched polymers and mPEs shows that information on branching structure could be inferred from rheological measurements on combinatorial sets of mixtures of an unknown branched with different combinations of linear polymers.

Thermomechanical Characterization of the Molecular Weight of Linear Polymers Exemplified by Natural Rubber

1964 ◽  
Vol 37 (1) ◽  
pp. 99-102
Author(s):  
B. Ya Teitelbaum ◽  
K. F. Gubanov
Keyword(s):  
Molecular Weight ◽  
Experimental Studies ◽  
Thermomechanical Properties ◽  
Linear Polymers ◽  
Molecular Weights ◽  
Calculated Molecular Weight ◽  
Low Degree ◽  
Wide Range ◽  
High Elasticity

Abstract In the previous work of Kargin and Slonimskii and that of Kargin and Sogolov who studied the behavior of polymers over a wide range of temperature, it was shown that the shape of thermomechanical curves depends on magnitude of molecular weight of the polymers. As a result of investigation of theory and actual experimental studies in which polyisobutylene was employed, it was demonstrated that molecular weight could be estimated on the basis of thermomechanical properties. This suggested a relationship between the magnitude of molecular weight M found from the thermomechanical curves and that which was determined from glass temperatures Tg and fluid temperatures Tf. For practical use of this relationship, it is necessary to know the magnitude of the segments and two empirical constants. These values can be found by calculation of molecular weights of three different fractions of the polymer. This can be accomplished experimentally by any independent method. Once these magnitudes are determined, it is necessary to find, by means of the thermomechanical curve, the values Tg and Tf, in order to calculate the molecular weight of any sample of the same polymer. Because of the low degree of accuracy of determination of these values, and because of the peculiar differences, the reliability of the calculated molecular weight cannot be great, especially since the equation utilizes the logarithm of the molecular weight figure and not the molecular weight itself. Apparently the graphic solution is simpler than analytical methods: by means of the data of thermomechanical studies for various fractions of known molecular weights it is possible to graph the dependence of M or log Mon Tf−Tg. From what has been said, it is evident that we may use the demonstrated method only for polymers of high elasticity, and furthermore, only for those fractions in which Tf−Tg is greater than zero.

LIQUIDUS THERMO-BAROMETER FOR THE MODELING OF MAGNETITE — MELT EQUILIBRIUM

2018 ◽  
pp. 71-80
Author(s):  
N. S. Aryaeva ◽  
E. V. Koptev-Dvornikov ◽  
D. A. Bychkov
Keyword(s):  
Experimental Data ◽  
Liquidus Temperature ◽  
Vertical Structure ◽  
Maximum Error ◽  
Silicate Melt ◽  
System Of Equations ◽  
Wide Range ◽  
Basaltic Melts ◽  
Multidimensional Statistics

A system of equations of thermobarometer for magnetite-silicate melt equilibrium was obtained by method of multidimensional statistics of 93 experimental data of a magnetite solubility in basaltic melts. Equations reproduce experimental data in a wide range of basalt compositions, temperatures and pressures with small errors. Verification of thermobarometers showed the maximum error in liquidus temperature reproducing does not exceed ±7 °C. The level of cumulative magnetite appearance in the vertical structure of Tsypringa, Kivakka, Burakovsky intrusions predicted with errors from ±10 to ±50 m.

Development of PEF extraction technology by Maguin

2015 ◽  
pp. 758-760
Author(s):  
Romain Delecourt ◽  
Loïc Marsal
Keyword(s):  
Sugar Beet ◽  
Electric Field ◽  
Pulsed Electric Field ◽  
Extraction Technology ◽  
Application System ◽  
Wide Range ◽  
Type Machine

Maguin (France) is still active in the application of pulsed electric field (PEF) technology. After having carried out successful tests on a 10 t/h pilot screw-type machine on sugar beet cossettes, a new application system based on a roller technology has been developed. This technology allows a wide range of application due to its flexibility with flowrates and materials. A variety of process schemes are proposed to ensure the best performance of the PEF technology.

scholarly journals Experimental analysis and ANN prediction on performances of finned oval-tube heat exchanger under different air inlet angles with limited experimental data

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 968-980
Author(s):  
Xueping Du ◽  
Zhijie Chen ◽  
Qi Meng ◽  
Yang Song
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Exchanger ◽  
Correlation Equation ◽  
Tube Heat Exchanger ◽  
Flow Friction ◽  
Air Inlet ◽  
Comparison Results ◽  
Wide Range ◽  
Oval Tube

Abstract A high accuracy of experimental correlations on the heat transfer and flow friction is always expected to calculate the unknown cases according to the limited experimental data from a heat exchanger experiment. However, certain errors will occur during the data processing by the traditional methods to obtain the experimental correlations for the heat transfer and friction. A dimensionless experimental correlation equation including angles is proposed to make the correlation have a wide range of applicability. Then, the artificial neural networks (ANNs) are used to predict the heat transfer and flow friction performances of a finned oval-tube heat exchanger under four different air inlet angles with limited experimental data. The comparison results of ANN prediction with experimental correlations show that the errors from the ANN prediction are smaller than those from the classical correlations. The data of the four air inlet angles fitted separately have higher precisions than those fitted together. It is demonstrated that the ANN approach is more useful than experimental correlations to predict the heat transfer and flow resistance characteristics for unknown cases of heat exchangers. The results can provide theoretical support for the application of the ANN used in the finned oval-tube heat exchanger performance prediction.

scholarly journals Recent Advancements in Polymer/Liposome Assembly for Drug Delivery: From Surface Modifications to Hybrid Vesicles

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1027
Author(s):  
Vincenzo De Leo ◽  
Francesco Milano ◽  
Angela Agostiano ◽  
Lucia Catucci
Keyword(s):  
Drug Delivery ◽  
First Generation ◽  
Phospholipid Bilayer ◽  
Bioactive Molecules ◽  
Systemic Delivery ◽  
Molecular Weights ◽  
Liposome Preparation ◽  
Wide Range ◽  
Liposome Surface

Liposomes are consolidated and attractive biomimetic nanocarriers widely used in the field of drug delivery. The structural versatility of liposomes has been exploited for the development of various carriers for the topical or systemic delivery of drugs and bioactive molecules, with the possibility of increasing their bioavailability and stability, and modulating and directing their release, while limiting the side effects at the same time. Nevertheless, first-generation vesicles suffer from some limitations including physical instability, short in vivo circulation lifetime, reduced payload, uncontrolled release properties, and low targeting abilities. Therefore, liposome preparation technology soon took advantage of the possibility of improving vesicle performance using both natural and synthetic polymers. Polymers can easily be synthesized in a controlled manner over a wide range of molecular weights and in a low dispersity range. Their properties are widely tunable and therefore allow the low chemical versatility typical of lipids to be overcome. Moreover, depending on their structure, polymers can be used to create a simple covering on the liposome surface or to intercalate in the phospholipid bilayer to give rise to real hybrid structures. This review illustrates the main strategies implemented in the field of polymer/liposome assembly for drug delivery, with a look at the most recent publications without neglecting basic concepts for a simple and complete understanding by the reader.

scholarly journals Sustainable Myrcene-Based Elastomers via a Convenient Anionic Polymerization

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 838
Author(s):  
David Hermann Lamparelli ◽  
Magdalena Maria Kleybolte ◽  
Malte Winnacker ◽  
Carmine Capacchione
Keyword(s):  
Anionic Polymerization ◽  
Sodium Hydride ◽  
Reactivity Ratios ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
Wide Range ◽  
Elastomeric Materials ◽  
Complete Study ◽  
Anionic Copolymerization ◽  
Trialkylaluminum Derivatives

Soluble heterocomplexes consisting of sodium hydride in combination with trialkylaluminum derivatives have been used as anionic initiating systems at 100 °C in toluene for convenient homo-, co- and ter-polymerization of myrcene with styrene and isoprene. In this way it has been possible to obtain elastomeric materials in a wide range of compositions with interesting thermal profiles and different polymeric architectures by simply modulating the alimentation feed and the (monomers)/(initiator systems) ratio. Especially, a complete study of the myrcene-styrene copolymers (PMS) was carried out, highlighting their tapered microstructures with high molecular weights (up to 159.8 KDa) and a single glass transition temperature. For PMS copolymer reactivity ratios, rmyr = 0.12 ± 0.003 and rsty = 3.18 ± 0.65 and rmyr = 0.10 ± 0.004 and rsty = 3.32 ± 0.68 were determined according to the Kelen–Tudos (KT) and extended Kelen–Tudos (exKT) methods, respectively. Finally, this study showed an easy accessible approach for the production of various elastomers by anionic copolymerization of renewable terpenes, such as myrcene, with commodities.

scholarly journals Modelling the Inflation and Elastic Instabilities of Rubber-Like Spherical and Cylindrical Shells Using a New Generalised Neo-Hookean Strain Energy Function

2021 ◽  
Author(s):  
Afshin Anssari-Benam ◽  
Andrea Bucchi ◽  
Giuseppe Saccomandi
Keyword(s):  
Experimental Data ◽  
Energy Function ◽  
Limit Point ◽  
Strain Energy ◽  
Cylindrical Shells ◽  
Strain Energy Function ◽  
Model Parameters ◽  
Wide Range ◽  
Cylindrical Tubes ◽  
Gent Model

AbstractThe application of a newly proposed generalised neo-Hookean strain energy function to the inflation of incompressible rubber-like spherical and cylindrical shells is demonstrated in this paper. The pressure ($P$ P ) – inflation ($\lambda $ λ or $v$ v ) relationships are derived and presented for four shells: thin- and thick-walled spherical balloons, and thin- and thick-walled cylindrical tubes. Characteristics of the inflation curves predicted by the model for the four considered shells are analysed and the critical values of the model parameters for exhibiting the limit-point instability are established. The application of the model to extant experimental datasets procured from studies across 19th to 21st century will be demonstrated, showing favourable agreement between the model and the experimental data. The capability of the model to capture the two characteristic instability phenomena in the inflation of rubber-like materials, namely the limit-point and inflation-jump instabilities, will be made evident from both the theoretical analysis and curve-fitting approaches presented in this study. A comparison with the predictions of the Gent model for the considered data is also demonstrated and is shown that our presented model provides improved fits. Given the simplicity of the model, its ability to fit a wide range of experimental data and capture both limit-point and inflation-jump instabilities, we propose the application of our model to the inflation of rubber-like materials.

scholarly journals Analysis of the Impact on the Mechanical Properties of Modification of Oligohydroxyethers in Organic Solvent Solution with Rubbers

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 519
Author(s):  
Vitalii Bezgin ◽  
Agata Dudek ◽  
Adam Gnatowski
Keyword(s):  
Mechanical Properties ◽  
Scientific Paper ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Wide Range ◽  
Strength Tests ◽  
Materials Used ◽  
Styrene Butadiene ◽  
The Impact

This paper proposes and presents the chemical modification of linear hydroxyethers (LHE) with different molecular weights (380, 640, and 1830 g/mol) with the addition of three types of rubbers (polysulfide rubber (PSR), polychloroprene rubber (PCR), and styrene-butadiene rubber (SBR)). The main purpose of choosing this type of modification and the materials used was the possibility to use it in industrial settings. The modification process was conducted for a very wide range of modifier additions (rubber) per 100 g LHE. The materials obtained in the study were subjected to strength tests in order to determine the effect of the modification on functional properties. Mechanical properties of the modified materials were improved after the application of the modifier (rubber) to polyhydroxyether (up to certain modifier content). The most favorable changes in the tested materials were registered in the modification of LHE-1830 with PSR. In the case of LHE-380 and LHE-640 modified in cyclohexanol (CH) and chloroform (CF) solutions, an increase in the values of the tested properties was also obtained, but to a lesser extent than for LHE-1830. The largest changes were registered for LHE-1830 with PSR in CH solution: from 12.1 to 15.3 MPa for compressive strength tests, from 0.8 to 1.5 MPa for tensile testing, from 0.8 to 14.7 MPa for shear strength, and from 1% to 6.5% for the maximum elongation. The analysis of the available literature showed that the modification proposed by the authors has not yet been presented in any previous scientific paper.

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