US3720099A - Testing of elastomeric materials - Google Patents

Testing of elastomeric materials Download PDF

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Publication number
US3720099A
US3720099A US00106129A US3720099DA US3720099A US 3720099 A US3720099 A US 3720099A US 00106129 A US00106129 A US 00106129A US 3720099D A US3720099D A US 3720099DA US 3720099 A US3720099 A US 3720099A
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United States
Prior art keywords
sample
recesses
undercut
section
testing
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Expired - Lifetime
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US00106129A
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English (en)
Inventor
H Pohnisch
S Wolff
P Herbrich
S Baumgart
U Arnold
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DEUTSCHE GOLD U SILBER SCHEIDEANSTALT DT
Evonik Operations GmbH
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Degussa GmbH
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
    • G01N11/10—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by moving a body within the material

Definitions

  • Wall means surrounds and defines an interior chamber [21] Appl. No.: 106,129 in which a sample of vulcanized elastomer is to be accommodated. At least two separate surfaces bound [30] Foreign Application Priority Data this chamber and are provided with undercut grooves of dovetail-shaped cross-section in which portions of Jan. 15, 1970 Germany ..P 20 01 613.1 the Sample are received. At least one Surface can be moved with reference to the other in a sense effecting [52] U.S.
  • the present invention relates to the testing of vulcanized elastomers. More particularly, the invention relates to an apparatus for such testing and to a testing method.
  • Vulkameters which are known to those skilled in the art and which, basically, operate on one of two principles: either by measuring torque (torsional-thrust Vulkameters) or by measuring thrust (linear-thrust Vulkameters). These devices are constructed and operate analogously to the shear-disk plastometer of Mooney which is described in German Industrial Norm DIN 52,523, or the AGFA Vulkameter which is described in Kautschuk und Gummi, (1957), pages 168-172.
  • test sample is accommodated in a chamber and is subjected therein to distending or deforming.
  • this is accomplished by a substantially mushroom-shaped rotor which extends into the chamber into contact with the sample and carries out a periodically changing rotation; in the case of linearthrust Vulkameters the chamber is provided in a twosection housing and one section is displaced with reference to the other.
  • test sample adhere properly and constantly to the surfaces with which it is in engagement, that is those bounding the chamber and, in case a separate rotor element is involved which acts upon the sample, also the surface of the rotor element.
  • the samples will shrink during vulcanization, a factor which can be proven by measuring the density of the sample during the vulcanizing process.
  • Such measurements indicate an increase in density which can only be the result of a decrease in volume, i.e. shrinkage.
  • shrinkage causes the sample to recede from the requisite intimate and constant contact with the aforementioned surfaces bounding the chamber, leading to inaccurate test results.
  • the diaphragm when the sample shrinks, the diaphragm is intended to continue to exert some pressure upon it due to the tendency on the part of the diaphragm to return to its undeflected rest position. Theoretically, this will maintain the sample in intimate engagement with the requisite surfaces of the testing apparatus; in practice, however, it has been found that this desired result is not always reliably achieved.
  • Another prior-art approach suggests adjusting the interior pressure in the test chamber via an actively adjustable diaphragm or an analogously acting component. This involves constant measuring of the interior pressure by a pressure-sensitive instrumentality, and comparison of the measured result with an established pressure factor; the difference between the measured pressure and the established factor serves as the basis for regulating the actual pressure in the interior of the chamber.
  • this approach is not only very complicated and hence subject to malfunction as well as being expensive; it, also, does not entirely preclude the development of the earlier-discussed undesirable conditions.
  • the prior art also suggests that the surfaces to which the sample is intended tointimately adhere, be provided with grooves or rectangular or rounded crosssection. Observation has shown that, although this measure somewhat retards the receding of the sample out of contact with the surfaces in question during shrinkage of the sample, it is not capable of preventing the final receding and separation so that the undesired conditions will occur, even through somewhat later than would otherwise be the case.
  • a concomitant object of the invention is to provide an improved testing apparatus for carrying out the novel method.
  • one feature of the invention resides in an apparatus for testing of vulcanizable elastomers which, briefly stated, comprises wall means having exposed surfaces which define with one another an interior chamber adapted to accommodate an elastomeric sample to be tested, at least one of these surfaces being movable with reference to the other.
  • the surfaces are provided, in accordance with the present invention, with recesses of undercut crosssection, and portions of the sample are accommodated in these recesses.
  • the portions accommodated in the undercut recesses will be prevented from such receding as soon as after a small initial amount of receding they are stopped from further movement of this type by contact with the faces bounding the undercut recesses.
  • FIG. 1 is a diagrammatic illustration of a prior-art torsional-thrust Vulkameter
  • FIG. 2 is a view similar to FIG. 1 but of a prior-art linear-thrust Vulkameter
  • FIG. 3 is a fragmentary sectioned detail view, on an enlarged scale, showing another prior-art embodiment
  • FIG. 4 is a view similar to FIG. 3 but showing still a further prior-art embodiment
  • FIG. 5 is a graph showing a test result achieved in the apparatus of FIG. 1;
  • FIG. 6 is a view similar to FIG. 5 but showing a test result obtained using the apparatus of FIG. 3 or 4;
  • FIG. 7 is a view similar to FIGS. 3 and 4, but showing an apparatus according to the present invention.
  • FIG. 8 is a view similar to FIGS. 5 and 6 but showing a graph of a test result obtained using the apparatus according to the present invention.
  • FIG. 9 is a graph comparing the test results shown in FIGS. 5, 6 and 8.
  • FIG. 1 DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail, and firstly the prior art apparatus in FIG. 1, it will be seen that this comprises a housing having two sections 1 and 2 which are provided with hollows facing one another and together defining the interior chamber 3. The sections 1 and 2 can be moved apart and together in the sense indicated by arrow 4 to permit access to the chamber 3.
  • a rotor 6 extends with its substantially mushroomshaped head into the interior of chamber 3 through an opening provided for this purpose in the section 2. Rotor 6 is turnable in the sense indicated by the curved arrow. Its surface, and the surfaces bounding the hollows in the sections 1 and 2, together define the testing chamber 3 in which the sample 5 of vulcanizable elastomeric material is accommodated for testing purposes.
  • FIG. 5 is a graph showing the test result achieved with the apparatus of FIG. 1. Explanations concerning the graph are given on the graph shown in FIG. 6.
  • FIG. 1 shows a torsional-thrust Vulkameter
  • FIG. 2 shows a linear-thrust Vulkameter.
  • the same reference numerals have been used in FIG. 2 to indicate components similar to those of FIG. 1. It is selfevident that, although the operation here is somewhat different in that the section 1 moves in the sense of arrow 4a to obtain the test results, there is nothing to prevent the receding of the sample 5 in the same manner as in FIG. 1.
  • FIG. 3 shows a portion of one of the surfaces bounding the chamber 3, namely one of the surfaces bounding the hollows in sections 1 and 2 or of the outer surface of the head of rotor 6.
  • the prior art provides, according to the embodiment shown in FIG. 3, that any and all of these surfaces may be provided with grooves 7 of rectangular cross-section. This improves adherence of the sample 5 to the respective surfaces.
  • grooves 8 may be of rounded or semi-circular cross-section as shown.
  • the apparatus a fragment of which is shown in FIG. 7, may be of either the type shown in FIG. 1 or the type shown in FIG. 2.
  • the grooves 9 are of dovetail-shaped undercut crosssection.
  • Measuring means MM has been shown diagrammatically, for measuring the physical characteristics of the sample which are to be determined; such measuring means is known per se and requires no detailed description.
  • the side faces include with the surface la and/or the transverse face 9 an angle of at least substantially 45. It is further advantageous not to provide all of the grooves in the respective surface bounding the chamber 3 as undercut grooves 9; instead, the grooves 9 should preferably alternate with grooves 7 of rectangular cross-section or with grooves 8 of rounded cross-section, such as are shown in FIGS. 3 and 4, respectively. As shown in FIG. 6 it is possible to use grooves 7 and 8 together, but either the grooves 7 or the grooves 8 may be used by themselvesalways in conjunction with grooves 9, of course.
  • FIG. 8 in a graph showing test results obtained with an apparatus according to the present invention, that is an apparatus of the type shown in FIG. 1 or in FIG. 2, but constructed in accordance with the present inventive concept as shown and described with reference to FIG. 6.
  • the graph in FIG. 8 shows a vulcanizing isothermal, with the sample tested being taken from an SBR-ISOO mixture.
  • a comparison with FIGS. 5 and 6 clearly indicates that in FIG. 8 the value in the terminal reaction period-measured between points D and E- is substantially better than in FIGS. 5 and 6.
  • the curve remains steady, whereas in FIGS. 5 and 6 it declines.
  • a decline of the torque peak takes place much earlier, so that the further progress of the curve (to the area between points D and E) is no longer characteristic.
  • the present invention completely avoids such problems in the manner and for the reasons discussed earlier, so that the curve shown in the graph of FIG. 8 is always obtained.
  • the decline in torque peak observed in torsional-thrust Vulkameters is completely eliminated, a significant increase in the accuracy and reliability of 'test results is obtained, and the test results are reproducible from case to case with a reliability not heretofore extant.
  • the present invention is applicable also when a required precise temperature control makes it necessary that the distance between sample and point of temperature regulation be as small as possible.
  • wall means having exposed surfaces which define with one another an interior chamber adapted to accommodate an elastomerrc sample to be tested, at least one of said surfaces being movable with reference to the other; a plurality of recesses of undercut cross-section provided in said surfaces for accommodating portions of said sample so as to prevent separation of the latter from said surfaces; and measuring means for measuring a physical characteristic of said sample while the latter is accommodated in said interior chamber.
  • undercut recesses are of substantially dovetail-shaped cross-section.
  • said undercut recesses each being bounded by a transverse surface portion inwardly spaced from the respective surface, and at least a pair of lateral surface portions extending from said transverse surface portion to the respective surface and including with at least one thereof an angle of at least substantially 45.

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  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Immunology (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
  • Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
  • Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)
  • Springs (AREA)
US00106129A 1970-01-15 1971-01-13 Testing of elastomeric materials Expired - Lifetime US3720099A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2001613A DE2001613B2 (de) 1970-01-15 1970-01-15 Vulkameter mit verbesserter Haftfestigkeit zwischen Gummiprüflcörper und Kammerwänden

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US3720099A true US3720099A (en) 1973-03-13

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US (1) US3720099A (enrdf_load_stackoverflow)
DE (1) DE2001613B2 (enrdf_load_stackoverflow)
GB (1) GB1317871A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4829830A (en) * 1987-04-25 1989-05-16 Japan Synthetic Rubber Co., Ltd. Apparatus for measuring viscoelasticity
US20070289363A1 (en) * 2006-06-19 2007-12-20 Andrew Grow Rheometer

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2679663A (en) * 1950-02-01 1954-06-01 Goodrich Co B F Marking of molded articles
US3182494A (en) * 1962-10-17 1965-05-11 Goodrich Co B F Viscurometer
US3538758A (en) * 1968-08-19 1970-11-10 Goodrich Co B F Test instrument for determining the physical properties of solid and liquid vulcanizable elastomeric materials

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2679663A (en) * 1950-02-01 1954-06-01 Goodrich Co B F Marking of molded articles
US3182494A (en) * 1962-10-17 1965-05-11 Goodrich Co B F Viscurometer
US3538758A (en) * 1968-08-19 1970-11-10 Goodrich Co B F Test instrument for determining the physical properties of solid and liquid vulcanizable elastomeric materials

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4829830A (en) * 1987-04-25 1989-05-16 Japan Synthetic Rubber Co., Ltd. Apparatus for measuring viscoelasticity
US20070289363A1 (en) * 2006-06-19 2007-12-20 Andrew Grow Rheometer
US7475592B2 (en) 2006-06-19 2009-01-13 Alpha Technologies Services Lcc Rheometer

Also Published As

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DE2001613C3 (enrdf_load_stackoverflow) 1974-08-15
GB1317871A (en) 1973-05-23
DE2001613B2 (de) 1974-01-10
DE2001613A1 (de) 1971-07-22

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