Rationalization of the Hardness Testing of Rubber

1936 ◽  
Vol 9 (1) ◽  
pp. 83-94
Author(s):  
J. R. Scott

Abstract The object of this paper is to draw attention to the present unsatisfactory state of the hardness testing of vulcanized rubber and the need for standardization of this test, and also to present some results of an investigation into the theoretical basis of hardness testing and the practical significance of hardness measurements. In this paper the word “hardness” will be used in the sense generally accepted in the rubber industry, that is, to denote resistance to indentation. The most commonly used types of hardness tester measure hardness in terms of the depth of the indentation made by a rigid ball or blunt pin pressed into the rubber by either a dead weight or a spring. The reading given by such an instrument, usually termed the hardness number, must depend on several variable factors, namely (1) the dimensions of the ball or pin; (2) the weight used to press it into the rubber, or the compression characteristics of the spring in the case of spring-loaded instruments; (3) the direction of the scale of the instrument, i. e., whether the reading increases with the depth of indentation, as in the Pusey-Jones Plastometer, or in the reverse direction, as in the Durometer; (4) the units in which the indentation is measured, i. e., whether in 100ths of a millimeter, 1000ths of an inch, or arbitrary units. In addition to these factors relating to the instrument, the reading must also depend on the dimensions of the rubber test-piece, especially its thickness, the nature of the rubber surface, and the period for which the ball or plunger is pressed on to the rubber before the reading is taken.

1944 ◽  
Vol 17 (1) ◽  
pp. 194-199
Author(s):  
H. A. Daynes ◽  
J. R. Scott

Abstract Tests have been made on numerous rubbers with the R.A.B.R.M. hardness gauge, the Strachan piezomicrometer, and the Pusey and Jones plastometer (using in each case ¼-in. and ⅛-in. diameter balls) and with the Shore durometer and Schopper hardness tester, to determine the relationships between the readings given by these instruments. The results are tabulated and represented graphically as correlation curves. A conversion chart is given by which the reading obtained with any one instrument or size of ball can readily be converted into the corresponding reading for any of the other instruments or sizes of ball.


1940 ◽  
Vol 13 (4) ◽  
pp. 969-978
Author(s):  
Lewis Larrick

Abstract The hardness test is one of the most useful and convenient physical tests which can be made on vulcanized rubber. It is easily made because the equipment can be simple, compact and portable. It is particularly useful in that the test sample may be a production article which can be put into service, undamaged, after the test. Consequently the test appears in the industry in several modifications, and the tester in diverse styles. Several more or less readily portable hardness testers are available commercially. The Shore Instrument and Manufacturing Co. has its line of Durometers, types A, B, C, D, etc.; Schopper, through Testing Machines, Inc., has marketed a tester similar to the Shore type A; the U. S. Gauge Co. has an instrument of the same type using the case of their pressure gage; the Firestone Penetrometer is another well-known tester of the spring-load type, as is the Adams Densimeter. At the present time the Society's Committee D-11 on Rubber Products is studying four portable hardness testers which are based on the specifications of the Standard Method of Test for Hardness of Rubber (D314-39), three of these being spring-operated instruments, the fourth, a dead-load type. In addition to the testers mentioned above, there is the Pusey-Jones Plastometer, which is a dead-weight hardness tester rather than a plastometer.


1939 ◽  
Vol 12 (1) ◽  
pp. 43-55
Author(s):  
J. R. Brown ◽  
E. A. Hauser

Abstract A CENTURY ago, Charles Goodyear in America and Th. Hancock in England found that the properties of crude rubber could be greatly improved by heating it with sulfur. The product resulting was more elastic, more resistant to tear and abrasion, less affected by solvents, and decidedly less thermoplastic. The treatment of rubber to give these desired properties is known generally as vulcanization and must be considered as the basis for the enormous growth of the rubber industry and the extensive use of rubber products in our everyday life. Broadly speaking, vulcanization involves the reaction, in some fashion, of sulfur with rubber. Extensive investigation has revealed other substances, such as benzoyl peroxide or polynitrobenzenes, which can transform rubber into a “vulcanized” condition. Experience has also shown that metallic salts of zinc or lead and especially certain organic compounds called “accelerators” greatly affect the rate of vulcanization, and these are favorably employed in practice. A vast amount of empirical knowledge has been gained which has greatly improved the practical application of vulcanization and the quality of rubber products, but which has failed as yet to reveal a complete picture of the true nature of the process.


Author(s):  
E.P. Kuznetsova

Currently, the issues of development of the regional economy, which require an effective solution, are becoming relevant for government and management bodies and the scientific community. One of the tools that contribute to solving the problems of the regional economy is the development of industrial cooperation. In this connection, the author made an attempt to study this process, as well as to develop comprehensive tools for managing the processes of industrial cooperation in the region (for example, Vologda Oblast). The work, on the basis of a sociological survey of the heads of enterprises of Vologda Oblast, reflects the state of cooperation in the region. An assessment of the level of development of cooperation is given, problems associated with a low level of interaction between enterprises, as well as lacking methods of efficiency from cooperation in the region are identified, in connection with which the author studied the management system of production cooperation in Vologda Oblast and proposed measures to improve it. The results obtained during the study contribute to the development and systematization of the theoretical basis of the problem under consideration. The practical significance of the work is related to the possibility of using the results of the research by researchers, graduate students, undergraduates, bachelors dealing with the problems of development of industrial cooperation.


2018 ◽  
Vol 61 (6) ◽  
pp. 348-353 ◽  
Author(s):  
Riku TAMURA ◽  
Yuji HIRAI ◽  
Hiroyuki MAYAMA ◽  
Yasutaka MATSUO ◽  
Takahiro OKAMATSU ◽  
...  

1934 ◽  
Vol 7 (3) ◽  
pp. 591-598 ◽  
Author(s):  
Paul Lüpke

Abstract Original Purpose The writer's first conception of an instrument for quickly measuring the resilience of rubber samples arose in connection with the basic idea for and development of the present A.S.T.M. hardness tester, in an endeavor to provide a reproducible means of measuring and expressing those properties of rubber compounds superficially apparent to the average user. It seemed that if the resistance to pressure (indenting or flexing) and the pressure, or force, of recovery, of a sample were duplicated, the article produced would “feel” the same as the sample, and under normal conditions of use would act mechanically the same. Nature of Problem This problem of measurement, as is generally known, is complicated by the time-hysteresis characteristic of vulcanized rubber compounds, arising through a dual nature, and causing them to manifest both elastic and plastic properties. Any instrument which applies load momentarily measures the almost purely elastic properties, while one which applies a more or less sustained load measures elastic properties modified by the material's partially plastic nature. These ideas are expressed from commercial and industrial viewpoints without regard to their possible deviations from the strict definitions accepted in physical science.


2013 ◽  
Vol 313-314 ◽  
pp. 1100-1104
Author(s):  
En Zhe Song ◽  
Chang Xi Ji ◽  
Mei Liang Yin ◽  
Jun Sun ◽  
Cheng Shun Yin

This paper establishes the mathematical model of the volume speed-modulating system and simulates dynamically with Matlab/Simulink. Provide a theoretical basis for algorithm of close loop control [ of the three variables which are diesel engines, variable pump and variable motor. Use PID control algorithm, through simulation and analysis, find out the parameter optimization adjustment rule [2,, seek matching operation between three variables. Provide a theoretical basis for the study on dynamic system of full-hydraulic loaders and have very important practical significance in realizing high efficiency energy saving and reducing energy consumption.


2012 ◽  
Vol 3 (2) ◽  
pp. 171-175 ◽  
Author(s):  
Farideh Bahrani ◽  
Mahroo Vojdani ◽  
Anahita Safari ◽  
Ghasem Karampoor

ABSTRACT Purpose The aim of this study was to evaluate mechanical property hardness and surface roughness (Ra) of different polymerization acrylic resins used for denture bases. Materials and methods A total of 30 specimens were prepared and divided in two groups. A total of 15 samples were processed by the compression molding technique using Meliodent (heatcured). Another 15 samples were processed with cold-cured resin Futura Gen via the injection molding technique. Hardness testing was conducted using a Vickers hardness tester. The Ra test was performed by a profilometer. Data were analyzed using the independent sample t-test and differences were statistically significant at the 0.05 level. Results The Vickers hardness numbers (VHN) were 20.8 ± 2.39 for Meliodent and 21.18 ± 1.42 for FuturaGen, which was not significantly different (p > 0.05). The Ra of Meliodent was 0.92 ± 0.23 µm and for FuturaGen it was 0.84 ± 0.37 µm. There were no significant changes in roughness. Conclusion The hardness and Ra of Meliodent and FuturaGen were not significantly different. Therefore, we recommend the use of FuturaGen for manufacturing denture base materials. How to cite this article Bahrani F, Safari A, Vojdani M, Karampoor G. Comparison of Hardness and Surface Roughness of Two Denture bases Polymerized by Different Methods. World J Dent 2012;3(2):171-175.


2020 ◽  
pp. 59-63
Author(s):  
Natalyа Bielousova

Goal. Consider the theoretical and methodological features of the development and implementation of inclusive rehabilitation and social tourism in Ukraine, with an emphasis on scientific approaches and research methods of inclusive tourism within the framework of social geography. Methodology. Analytical, statistical, graphic, systemic and comparative geographical methods were used. Approbation. The main conceptual issues of the scientific and theoretical basis of research activities in the direction of inclusive tourism were investigated both by domestic students (L. Barmashina, N. Belousova, S. Derevyanko, O. Zayarnuk, L. Naumenko and others) and by foreign scientists (A. Bavelsky , A. Dyskin, S. Makhov, A. Sesolkin, E. Sigida, D. Chepik) and have been tested in the previous works of the author of this article. Scientific novelty. Using the experience of foreign countries, where inclusive tourism has been widely developed and has a high efficiency of implementation, we propose priority steps for the development of inclusive social and rehabilitation tourism in Ukraine in the form of scientific approaches as components of the theoretical and methodological base of the study. Practical significance. The article raises controversial issues related to the scientific and theoretical basis, in the form of scientific approaches to socio-geographical research of inclusive tourism in Ukraine. The main subjects of rehabilitation processes in the development of inclusive tourism are people with disabilities, as representatives of the most vulnerable inclusive category. The materials of the publication can be used in further scientific research on this topic, in the process of work of departments and specialized institutions that provide rehabilitation services for people with disabilities, and also relate to the tourism sector.


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