The Rheology of Raw Rubber

1937 ◽  
Vol 10 (2) ◽  
pp. 214-223 ◽  
Author(s):  
M. Mooney
Keyword(s):  
Rheological Properties ◽  
Capillary Tube ◽  
Elastic Recovery ◽  
Rotating Cylinder ◽  
Test Material ◽  
Rotating Disc ◽  
Mechanical Working ◽  
Considerable Uncertainty ◽  
Control Work ◽  
Cylinder Viscometer

Abstract The scientific measurement of the rheological properties of raw or unvulcanized rubber is a problem that has required new methods in rheological laboratory technic. Hot, moderately milled, or masticated raw rubber exhibits to a very marked degree each of the three properties of elasticity, plasticity, and thixotropy. It is highly elastic (not perfectly elastic), in that if deformed and released quickly it can take a large deformation and still return to its initial form. It is highly plastic, in that under proper conditions it can be deformed to any given extent permanently and without rupture. It is highly thixotropic, in that its viscosity or stiffness is very considerably decreased by brief mechanical working or mastication, and the lost viscosity is largely regained again when the mastication ceases. Obviously such a wide and varied range in rheological properties cannot be measured in either of the two types of rheological instruments, the compression and the extrusion plastometers, commonly used for raw rubber. There is no way in either instrument to determine or correct for thixotropy; and the viscosity can only be calculated with considerable uncertainty and difficulty. For example, thixotropy has not been considered in either of the already very complicated analyses of parallel plate plastometry by Peek and by Scott. Peek and Erickson have attempted to analyze the effects of thixotropy and elasticity in capillary tube viscometry without obtaining a complete or generally useful solution. However useful the compression and extrusion plastometers may be in factory control work, they are inadequate as scientific research instruments. The rotating cylinder viscometer seems to be the only type of instrument that meets the requirements of the problem considered. It allows an unlimited deformation of the test material, the previous deformation history can be controlled at will, and the subsequent elastic recovery can be measured if desired. There are two serious deficiencies of the conventional cylindrical viscometer, as applied to raw rubber, in that, first, the rubber, being semi-solid, would be likely to slip on the moving surfaces; secondly, if the rubber did not slip but sheared as it should, it would soon roll and climb out of the viscometer against the force of gravity. These deficiencies can be corrected, first, by fluting or otherwise roughening the cylindrical surfaces so that they grip the rubber and prevent slipping; secondly, by adding means for compressing and holding the rubber in place. The combined use of these two devices in a factory control instrument, the rotating disc plastometer, has already been described; and a rotating cylinder viscometer with similar features was referred to in the same article. The cylindrical viscometer there referred to was used in the experimental researches described below. Since this instrument is so different in several respects from the conventional cylindrical viscometers and, furthermore, is designed to facilitate the measurement of thixotropy and elastic recovery as well as viscosity, it seems appropriate to give it a new name and call it a rubber rheometer.

Study of the effect of mechanical working on the rheological properties of some potential artificial lubricants for human joints

1971 ◽  
Vol 10 (1) ◽  
pp. 21-27 ◽  
Author(s):  
M. A. M. A. Younes ◽  
P. S. Walker ◽  
P. C. Seller ◽  
D. Dowson ◽  
V. Wright
Keyword(s):  
Rheological Properties ◽  
Mechanical Working ◽  
Human Joints

Circulation control in magnetohydrodynamic rotating flows

2017 ◽  
Vol 829 ◽  
pp. 328-344 ◽  
Author(s):  
V. D. Borisevich ◽  
E. P. Potanin ◽  
J. Whichello
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Exact Analytical Solution ◽  
External Rotation ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Rotating Cylinder ◽  
Rotating Disc ◽  
Angular Velocities ◽  
Energy Equations

A model of a laminar viscous conducting flow, near a dielectric disc in a uniform magnetic field and in the presence of external rotation, is considered, where there is a uniform suction and an axial temperature gradient between the flow and the disc’s surface. It is assumed that the parameters of the suction or the magnetohydrodynamic (MHD) interaction are such that the nonlinear inertial terms, related to the circulation flow, are negligible in the differential equations of the MHD boundary layer on a rotating disc. Analysis of the motion and energy equations, taking the dependence of density on temperature into account, is carried out using the Dorodnitsyn transformation. The exact analytical solution for the boundary layer and heat transfer equations is obtained and analysed, neglecting the viscous and Joule dissipation. The dependence of the flow characteristics in the boundary layer on the rate of suction and the magnetic field induction is studied. It is shown that the direction of the radial flow in the boundary layer on a disc can be changed, not only by variation of the ratio between the angular velocities in the external flow and the boundary layer, but also by changing the ratio of the temperatures in these two flows, as well as by varying the hydrodynamic Prandtl number. The approximate calculation of a three-dimensional flow in a rotating cylinder with a braking disc (or lid) is carried out, demonstrating that a magnetic field slows the circulation velocity in a rotating cylinder.

Apparent Viscosity and Rheological Behavior of Aluminum-Alloy Slurry Containing Nano-Sized SiC Particles

2019 ◽  
Vol 285 ◽  
pp. 391-397
Author(s):  
Kang Lu ◽  
Shu Sen Wu ◽  
Shu Lin Lü ◽  
Chong Lin
Keyword(s):  
Aluminum Alloy ◽  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Mass Fraction ◽  
Matrix Alloy ◽  
Rotating Cylinder ◽  
Viscous Force ◽  
Semi Solid ◽  
The Relationship ◽  
Cylinder Viscometer

The apparent viscosity and rheological behavior of nanoSiCP/Al-5Cu composites were studied by using a high temperature coaxial rotating cylinder viscometer. The results show that mass fraction of nanoSiCP is an important factor for apparent viscosity of the nanoSiCP/Al-5Cu composites, and there is a great enhancement of apparent viscosity of the slurry with the increase of nanoSiCp content. It can attribute to the viscous force between nanoSiCp and matrix alloy melt above the liquidus. The increased amplitude of apparent viscosity in semi-solid state is far less than those in liquid state with the increase of mass fraction of nanoSiCp. The apparent viscosities of the composites reinforced with 0.5%, 1%, 1.5% and 2% nanoSiCp at 700°C were 24.78%, 95.25%, 160.29% and 228.62% higher than that of Al-5Cu alloy, respectively. Besides, the rheological model of nanoSiCP/Al-5Cu composites was established based on the fitting curve, which can precisely describe the relationship between the apparent viscosity of nanocomposites slurry and nanoSiCp mass fraction.

The Pendulum as a Source of Energy for Plasticity Measurements

1936 ◽  
Vol 9 (4) ◽  
pp. 626-632
Author(s):  
Ira Williams
Keyword(s):  
Plastic Flow ◽  
Parallel Plate ◽  
Elastic Recovery ◽  
Time Factor ◽  
Mathematical Treatment ◽  
Parallel Plates ◽  
Simple Apparatus ◽  
Constant Area ◽  
Rapid Control ◽  
Control Work

Abstract ADVANCEMENT in methods for studying the consistency of rubber during the last 10 years has been confined largely to various modifications of previous tests and to better interpretation of the data obtained. The extrusion plastometer introduced by Marzetti (11) has been modified by Behre (1) to provide a battery of instruments, by Dillon and Johnston (5) to provide more simple apparatus capable of operating at increased rates of shear, and by Dillon (4) to provide an instrument for rapid control work. The parallel-plate plastometer (16) has received numerous modifications of form. DeVries (2) modified the plates to provide a constant area of contact with the rubber. This modification was used by van Rossem and van der Meyden (14) who stressed the necessity of following the elastic recovery as well as the rate of compression. Karrer (8) pointed out the need for controlling the time factor during compression and recovery and has described an instrument (9) with which each measurement requires about 30 seconds. The balance plastometer, which employs parallel plates, was described by Hoekstra (7) and is well adapted to following the elastic recovery after the rubber has been compressed under any conditions of thickness and time. A parallel-plate instrument with interchangeable parts to provide various methods of applying pressure and following recovery was described by Lefeaditis (10). The relation between compression and the extent of recovery has been considered by Dillon (3), who concluded that the measurement of either the compression or the elastic recovery as obtained with the usual parallel-plate plastometer was sufficient if the comparison was confined to a number of batches of a given stock or type of rubber. He also pointed out that elastic recovery depends on the speed of the previous deformation. Hoekstra (6), after considering some of the factors involved in plastic flow, concluded that elastic recovery should be measured only after compression of a rubber to the fixed thickness. The general usefulness of the parallel-plate plastometer has been greatly increased by the mathematical treatment of Peek (13) and Scott (15). A third type of plastometer, consisting of a disk which rotates in compressed rubber while the resistance to shear is measured, has been described by Mooney (12).

Rheological Properties of an Electrorheological Fluid in Original Transition Zone

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1893-1900
Author(s):  
Fan Zhikang ◽  
Liang Shuhua ◽  
Xue Xu ◽  
Wang Gang
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Transition Zone ◽  
Electrorheological Fluid ◽  
Concentric Cylinder ◽  
Pseudoplastic Fluid ◽  
Applied Fields ◽  
Er Fluid ◽  
Regressive Analysis ◽  
Cylinder Viscometer

The rheological properties of an electrorheological(ER) fluid have been studied in a modified concentric cylinder viscometer. The results show that the relation of shear rate and shear stress is non-linear at certain shear rate defined as an original transition zone. Regressive analysis reveals that the ER fluid is of yield-pseudoplastic fluid in the transition zone. With increase in applied fields, the rheological properties of the ER fluid deviates from Newtonian fluid and the length of the transition zone becomes longer.

Plasticization of Natural and Synthetic Rubbers. II. GR-S

1949 ◽  
Vol 22 (2) ◽  
pp. 518-534 ◽  
Author(s):  
G. H. Piper ◽  
J. R. Scott
Keyword(s):  
Natural Rubber ◽  
Plastic Flow ◽  
Elastic Recovery ◽  
Mechanical Action ◽  
Shear Stresses ◽  
Mechanical Working ◽  
Chain Molecules ◽  
Peptizing Agent ◽  
Set Up ◽  
Internal Mixer

Abstract Continuing the work described in Part I, experiments have been made to determine the separate effects of heat, oxidation, mechanical working on rolls or in an internal mixer, peptizing agents (used in hot milling), and absorption of softener on the softness, elastic recovery, and plastic flow relation (between applied force and rate of flow) of GR-S. Heat alone, without oxygen or mechanical action, does not soften GR-S, but makes it harder and more elastic, presumably by inducing cross-linking of the chain molecules; GR-S thus differs fundamentally from natural rubber, which can be softened by heat. Absorption of softener (mineral oil) softens GR-S and reduces its recovery, but these effects are too small to form a practicable plasticizing method. Either oxidation or mechanical working softens GR-S considerably, reduces its elastic recovery, and brings its plastic flow relation nearer to that of well masticated natural rubber, i.e., approaching ordinary viscous or Newtonian flow (flow rate proportional to stress). Peptizing agents such as benzaldehyde phenylhydrazone or iron naphthenate promote the effect of hot milling, presumably by accelerating oxidation, which is shown to occur during hot, but not appreciably in cold, milling. Of the methods tried, those which plasticize GR-S most quickly are (1) hot milling with a peptizing agent, and (2) oxidation at 125° C and 15 lb. per sq. in. oxygen pressure ; if the latter is continued too long, however, hardening sets in. The results show that GR-S, like natural rubber, can be plasticized by mechanical breakage of the chain molecules by the shear stresses set up during mastication, as well as by oxidation, which presumably causes breakage of the molecules at the double bonds. Mechanical and oxidative treatments, however, do not give the same properties ; mechanical breakdown in the cold gives a product completely soluble in benzene, whereas oxidation does not, and is less effective in reducing recovery, and there may be other differences not yet revealed. In view of these differences and the fact that heat has effects opposite to oxidation or mechanical working, it follows that the various possible ways of plasticizing GR-S, since they involve heat, oxidation, and mechanical action in different combinations and degrees, give plasticized batches with very different properties, even if the length of the treatments is so adjusted as to give, say, the same Williams or Mooney plasticity reading. These differences are fully discussed in the present paper; the main conclusions are:

Experiments with a rotating cylinder viscometer in liquid helium II

1953 ◽  
Vol 49 (4) ◽  
pp. 717-727 ◽  
Author(s):  
A. C. Hollis-Hallett
Keyword(s):  
Liquid Helium ◽  
Normal Component ◽  
Rotating Cylinder ◽  
Mutual Friction ◽  
Rotating Fluid ◽  
Helium Ii ◽  
Lambda Point ◽  
New Type ◽  
Coefficient Of Viscosity ◽  
Cylinder Viscometer

ABSTRACTLiquid helium II was contained in the annular space between two co-axial cylinders, the inner of which was suspended by a torsion fibre while the outer was rotated at constant speeds. The torque upon the inner cylinder produced by the rotating fluid was measured for various steady velocities between 0·1 and 3 cm.sec.1, and was not found to be directly proportional to the velocity of rotation at any temperature between the lambda-point and 1·15° K. This result suggests that there must be some new type of non-linear frictional force acting in the liquid, possibly in addition to the Gorter-Mellink force of mutual friction.Extrapolation of the experimental results to zero velocity gives values of the coefficient of viscosity of the normal component which agree with the oscillating disk values between the lambda-point and about 1·6° K. At lower temperatures, the present results are significantly lower, suggesting, perhaps, that the values of the normal component density used in the analysis of the oscillating disk results were too low.

Paper 9: A Rotating Cylinder Viscometer for Measurement at Elevated Temperature and Pressure

1965 ◽  
Vol 180 (10) ◽  
pp. 153-162
Author(s):  
J. Wonham
Keyword(s):  
High Pressures ◽  
Rotating Cylinder ◽  
Wide Range ◽  
New Instrument ◽  
Temperature And Pressure ◽  
Major Alteration ◽  
Set Up ◽  
The Many ◽  
High Degree ◽  
Cylinder Viscometer

This paper records some of the recent experimental methods used to determine the viscosity of water. In drawing attention to the many techniques used (most relying upon calibration of the instrument by a fluid of known viscosity), the conclusion may be drawn that an absolute instrument is required which will produce results over a wide range of temperature and pressure. It has long been known that the rotating cylinder viscometer is capable of a high degree of accuracy, but technical considerations have, in the past, restrained most workers from pursuing this method at high pressures. Progress in the development of the rotating cylinder instrument for these conditions is described and specific problems encountered with this method are discussed. This work is a continuation of the design studies of Kjelland-Fosterud (1)† and Whitelaw (2) who both gave considerable thought to the problems associated with this type of instrument. The first instrument to be tested by the author was based on Whitelaw's design but it was found that certain aspects of this instrument required major alteration. A new instrument was set up and has been found suitable for accurate viscosity determination.

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