Preparation of Highly Purified Hevea Rubber

1949 ◽  
Vol 22 (3) ◽  
pp. 731-734 ◽  
Author(s):  
G. T. Verghese
Keyword(s):  
Mechanical Treatment ◽  
New Method ◽  
Rubber Latex ◽  
Rubber Particles ◽  
High Degree

Abstract A new method is described by which rubber hydrocarbon of a high degree of purity can be obtained without resorting to any drastic chemical or mechanical treatment of the rubber. Rubber latex is treated with ammonium oleate, which displaces the proteins from the surface of the rubber particles. The displaced proteins, along with other nonrubber substances present in the serum, are removed by repeated creaming of the latex. Finally, the creamed latex is “solubilized” in n-hexane, and the rubber precipitated by adding acetone.

About Determing the Microhardness of Composite Coatings

2021 ◽  
Vol 1037 ◽  
pp. 486-493
Author(s):  
Sergey Y. Zhachkin ◽  
Anatoly I. Zavrazhnov ◽  
Nikita A. Penkov ◽  
George V. Kudryavtsev ◽  
Paul V. Tsisarenko
Keyword(s):  
Composite Coating ◽  
Mechanical Treatment ◽  
Composite Coatings ◽  
Operational Parameters ◽  
Deposition Parameters ◽  
Cylinder Liners ◽  
High Degree ◽  
Applied Coating ◽  
Positive Effect ◽  
Selection Of

One of the fundamental tasks in restoring the operability of cylinder liners is the application of a composite coating with a predetermined microhardness value. The authors have developed a technology for applying composite coatings based on iron on cylindrical surfaces, which makes it possible to vary the physical, mechanical and operational parameters of the formed iron-containing coating due to the planned selection of the deposition parameters. This eliminates the need for mechanical treatment of the applied coating, which is the reason for the high degree of rejection parts that undergo the iron-on operation. Contact interaction of the working tool with the formed layer of the composite coating has a positive effect on the value of its roughness.

The State of Polydispersion of Hevea Latex. I

1946 ◽  
Vol 19 (1) ◽  
pp. 176-186
Author(s):  
J. H. E. Hessels
Keyword(s):  
Protein Content ◽  
Hevea Brasiliensis ◽  
The State ◽  
Rubber Content ◽  
Rubber Latex ◽  
Latex Particles ◽  
Rubber Particles ◽  
The Subject ◽  
Points Of View ◽  
Good Agreement

Abstract The rubber particles in the latex of Hevea brasiliensis are present in the form of a polydispersion, and their diameters lie within the range of 0.1 to 3 microns. The rubber hydrocarbon itself is composed of a mixture of macromolecules of different degrees of polymerization. Rubber latex is, therefore, a system which is at the same time both polydispersed and polymolecular. It is well known that the degree of dispersion of a substance governs to a great extent certain properties of the substance. Moreover, astonishing as it may seem, in the great number of investigations which have been made of the composition and properties of latex and crude rubber, almost no attention has been paid to the part which may be played by the dimensions of the latex particles. However, in an investigation concerned with the centrifugation of latex, Loomis and Stump have called attention to this possibility, and in a study of latex obtained by fractionation, and in which the majority of the latex particles were of large dimensions, McGavack came to the conclusion that the protein content is proportional to the surface area of the globules. This limited knowledge of the subject seemed to warrant a more thorough study of the problem, which is of fundamental importance both from the theoretical and practical points of view. The investigation as a whole divided itself into three essential parts: (1) separation of latex into fractions containing particles of different sizes, and measurement of the state of dispersion in these fractions, (2) a study of the relation of these fractions to the composition of the rubber, i.e., the relation between the content of nonrubber components and the size of the latex particles, and (3) a study of the changes in the properties of the rubber hydrocarbon with change in the size of the latex particles. The latex used in this investigation was ordinary latex, containing 38–40 per cent dry-rubber content and preserved with ammonia. For the most important points, a concentrated latex (creamed latex containing 60 per cent dry-rubber content) was also tested. These two latices were about two years old when the investigation was started, and they gave results which were in good agreement with each other. In the present paper, only the data obtained with the first of the two latices are presented.

The Identification of Accelerated Coagulability

1977 ◽  
Author(s):  
J.A. Caprini ◽  
L. Zuckerman ◽  
E. Cohen ◽  
J.P. Vagher ◽  
V. Lipp
Keyword(s):  
General Population ◽  
Cancer Patients ◽  
Whole Blood ◽  
Clinical Applications ◽  
New Method ◽  
Blood Collection ◽  
Normal Individuals ◽  
Coagulation Tests ◽  
High Degree ◽  
Incorrect Classification

This report describes a new method for comparing overall clotting characteristics between normal individuals and those with proven malignancy using thrombelastographic (TEG) comparison of native and celite-activated specimens. Native whole blood TEG, celite-activated TEG, and standard coagulation tests were performed on the same blood collection in 90 normals and 90 patients with new malignancies and the results were used to derive a discriminate equation This equation classified correctly all 90 normals and 88 out of 90 cancer patients. The formulation was verified with an additional 82 patients with only one incorrect classification in the 31 cancer subjects. The standard coagulation tests did not discriminate without significant overlap between cancer patients and normals. The high degree of discrimination obtained with our TEG analysis provides a new tool to compare individual clotting differences that may have important clinical applications. However, the results cannot be extrapolated to selectively identify those with malignancy among the general population since many other stimuli may produce accelerated coagulability. This analysis does provide identification of accelerated coagulability in association with new malignancies.

A New Method for High-Degree Spline Interpolation: Proof of Continuity for Piecewise Polynomials

2019 ◽  
Vol 63 (3) ◽  
pp. 655-669
Author(s):  
A. Pepin ◽  
S. S. Beauchemin ◽  
S. Léger ◽  
N. Beaudoin
Keyword(s):  
Fourier Transform ◽  
Discrete Fourier Transform ◽  
Spline Interpolation ◽  
Higher Order ◽  
New Method ◽  
System Of Equations ◽  
Piecewise Polynomials ◽  
Odd Degree ◽  
High Degree

AbstractEffective and accurate high-degree spline interpolation is still a challenging task in today’s applications. Higher degree spline interpolation is not so commonly used, because it requires the knowledge of higher order derivatives at the nodes of a function on a given mesh.In this article, our goal is to demonstrate the continuity of the piecewise polynomials and their derivatives at the connecting points, obtained with a method initially developed by Beaudoin (1998, 2003) and Beauchemin (2003). This new method, involving the discrete Fourier transform (DFT/FFT), leads to higher degree spline interpolation for equally spaced data on an interval $[0,T]$. To do this, we analyze the singularities that may occur when solving the system of equations that enables the construction of splines of any degree. We also note an important difference between the odd-degree splines and even-degree splines. These results prove that Beaudoin and Beauchemin’s method leads to spline interpolation of any degree and that this new method could eventually be used to improve the accuracy of spline interpolation in traditional problems.

scholarly journals A New Method to Make 24-Hour Urine Collection More Convenient: A Validity Study

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Pooneh Nabavizadeh ◽  
Shadi Ghadermarzi ◽  
Mohammad Fakhri
Keyword(s):  
Healthy Volunteers ◽  
Sampling Method ◽  
Urine Volume ◽  
New Method ◽  
Validity Study ◽  
Urine Collection ◽  
Protein Levels ◽  
Collection Device ◽  
Fixed Proportion ◽  
High Degree

Background and Objectives. This study proposes a novel urine collection device that can divide each urine collection into 20 parts and store and cool just one part. The aim of the current study is to compare measured biomarkers from the proposed urine collection device to those of conventional 24-hour sampling method. We also hypothesized that the new method would significantly increase patients’ adherence to the timed urine collection.Methods. Two 24-hour urine samples with the conventional method and with the new automated urine collection device that uses just one-twentieth of each void were obtained from 40 healthy volunteers. Urine parameters including volume, creatinine, and protein levels were compared between the two methods and the agreement of two measurements for each subject was reported through Bland-Altman plots.Results. Our results confirmed that for all three variables, there is a positive correlationP<0.001between the two measurements and high degree of agreement could be seen in Bland-Altman plots. Moreover, more subjects reported the new method as “more convenient” for 24-hour urine collection.Conclusions. Our results clearly indicate that a fixed proportion of each void may significantly reduce the urine volume in timed collections and this, in turn, may increase subjects’ adherence to this difficult sampling.

Some Properties of Rubber Latex

1938 ◽  
Vol 11 (3) ◽  
pp. 479-481
Author(s):  
Ernst Schmidt ◽  
Paul Stamberger
Keyword(s):  
Aqueous Phase ◽  
Electrophoretic Deposition ◽  
Distilled Water ◽  
Cent Solution ◽  
Rubber Latex ◽  
Rubber Particles ◽  
Serum Components

Abstract Rubber latex of the commercial type preserved by ammonia was freed almost completely of its serum components by a method involving two steps: 1. Electrophoretic deposition of the rubber particles on a membrane, followed by 2. Dispersion of the resultant paste in a 0.6-per cent solution of ammonia in distilled water. This process was repeated until the aqueous phase obtained from this separation was free of non-rubber components in the latex.

The Effect of Heat on Raw Rubber in the Presence and Absence of Air

1928 ◽  
Vol 1 (2) ◽  
pp. 299-306
Author(s):  
J. D. Fry ◽  
B. D. Porritt
Keyword(s):  
Mechanical Treatment ◽  
Cold Water ◽  
Solution Viscosity ◽  
Apparent Difference ◽  
Normal Process ◽  
Mechanical Working ◽  
Rubber Particles ◽  
Presence And Absence ◽  
Physical Changes

Abstract During the process of milling or masticating rubber, three agents, namely, mechanical working, heat, and the constituents of the air, are evidently present which may be individually or collectively responsible for the resulting physical changes. The generally accepted explanation of the effects produced is that the mechanical treatment breaks down some form of structure existing in the raw rubber or rubber particles and consequently it is customary to describe material as “overworked” when milling has been carried too far, and to reserve the terms “burnt” and “scorched” for cases in which the heat generated in the process has caused premature vulcanization. The correctness of the assumption that milling is essentially a mechanical operation at first sight seemed to be supported by an experiment made by one of the authors in which the treatment was carried out under a stream of cold water when it was found that the solution viscosity of the material diminished in much the same way as in the normal process, the only apparent difference in the final product being the almost complete absence of the adhesiveness characteristic of milled rubber. Further consideration, however, suggested that though the conditions under which the test was made undoubtedly minimized contact with air and the development of heat, the possibility that oxygen might still play a part was not entirely excluded, while the fact that the bulk of the rubber was kept cold did not necessarily preclude local rises in temperature taking place in the material when passing between the rolls.

scholarly journals ON THE SEISMIC HAZARD IN THE AZERBAIJAN TERRITORY

2014 ◽  
Author(s):  
Т.Я. Маммадли
Keyword(s):  
Seismic Hazard ◽  
New Method ◽  
Seismic Zoning ◽  
The Real ◽  
High Degree

Анализируются предыдущие и ныне действующие карты сейсмического районирования территории Азербайджана, методы их составления. Отмечается неадекватность этих карт на реальную сейсмическую опасность. Предлагается новый метод оценки сейсмической опасности. Выявлена высокая дифференциация сейсмической сотрясаемости территории Азербайджана в пространстве и по степени ее проявления. The previous and now acting maps of the seismic zoning of the Azerbaijan territory, the methods of their composition are analyzed. The inadequacy of these maps to the real seismic danger is noted. The new method of evaluating the seismic danger is proposed. The high degree of the seismic shakability differentiation of the Azerbaijan territory in the space and according to the degree of its manifestation is revealed.

Anode Process for Rubber Articles and Coatings

1933 ◽  
Vol 6 (4) ◽  
pp. 537-548 ◽  
Author(s):  
C. L. Beal
Keyword(s):  
Organic Compounds ◽  
Alkaline Medium ◽  
Colloidal Particles ◽  
Water Phase ◽  
Inorganic Salts ◽  
Brownian Movement ◽  
Rubber Latex ◽  
Butter Fat ◽  
Rubber Particles ◽  
Anode Process

Abstract THE term “anode process” has been chosen and used widely in the trade to designate a fundamental method for the production, directly from rubber latex, rapidly, and in one application, of articles and coatings of the highest grade of unmasticated rubber. Rubber latex, a milky exudation from the bark of rubber trees, is composed chiefly of tiny particles of rubber suspended in a water phase or serum, not unlike globules of butter fat in milk. Rubber latex contains small amounts of many organic compounds and inorganic salts. Some of these non-rubber materials, such as the proteins and resins, are considered to be adsorbed on the surfaces of the rubber particles and to be responsible for many of the colloidal characteristics of latex. As it comes from the tree, the latex is unstable and coagulates easily, but, when stabilized with ammonia, it can be safely shipped and stored for long periods. Like most colloidal particles in suspension in an alkaline medium, the rubber particles of ammoniated latex are negatively charged through the adsorption of hydroxyl anions. The particles, many as small as 1/25,000 inch in diameter, are in constant oscillation (Brownian movement) and are kept from hitting one another and sticking together (coagulating) by the repulsion of their electric charges. When the hydroxyl ions are neutralized or otherwise removed from the particles, the electric repulsion between particles disappears and coagulation results.

Some Applications of High-Frequency Electric Currents to the Latex Industry

1938 ◽  
Vol 11 (3) ◽  
pp. 570-574
Author(s):  
Henri Leduc
Keyword(s):  
Dielectric Loss ◽  
Electric Field ◽  
Electric Fields ◽  
High Frequency ◽  
Specific Effect ◽  
Entire Body ◽  
Rubber Latex ◽  
Joule Effect ◽  
High Frequency Electric Field ◽  
Rubber Particles

Abstract The “radiocoagulation” of latex has been developed in the laboratories of L'Office National des Recherches et Inventions by Dufour and Leduc, who conceived the idea of applying the effect of electric fields of high frequency to rubber latex. When latex is exposed to the action of an electric field of high frequency, the entire body of liquid is heated uniformly, provided that the electric field itself is uniform. The causes of this heating effect are difficult to ascertain because various phenomena are involved simultaneously, e. g., a dielectric loss in the rubber and a loss by the Joule effect in the serum. Each of these effects is, according to conditions, the predominant one, e. g., by increasing the conductivity of the serum, electrolytes such as sodium sulfate or ammonium sulfate increase the Joule loss, U2/R, whereas an increase in the concentration of latex tends to increase the dielectric loss. Finally, since rubber particles are not electrically neutral, they are subject to alternating forces of the electric field, which is a specific effect of the high frequency, and these forces impart to the rubber particles movements throughout the liquid. Now latex can be rendered sensitive to mechanical forces, i. e., some mixtures can be coagulated by slight agitation. Accordingly it is conceivable that a high-frequency electric field, by setting the rubber particles in motion throughout the emulsion, is capable of coagulating a mass of latex exposed to the field.

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