Standard hardness rubber

The seals in the clamp comprise either a standard hardness rubber (SHR) or a high hardness rubber (HHR), both of which are prepared via water-jet cutting from larger sheets. The seal is applied in a picture frame conhguration each half-clamp has an associated fully enclosed semicircular annulus, thus preventing fluid (leaking from a... 

The standard briefly covers the significance of hardness in terms of its relation with modulus, and the practical use of hardness tests. The hardness tests for rubber that are standardized by ISO are introduced and the distinction between dead load and durometer type instruments is explained to help with selection of a test method for particular circumstances. The effect of test piece, use of standard hardness blocks and comparison of hardness scales is also outlined. 

For many years there was no move to produce an international standard for durometers but one was eventually published in 1986. ISO 7619 is now in two parts44,45, separating a meter calibrated in IRHD from the others. Part 1 now covers the Shore A and D type meters, a meter designated AO for soft materials and a micro Shore type meter designated AM. The Shore A scale corresponds approximately to the IRHD scale and the D scale can conveniently be used for hard rubbers above about 90 Shore A. The AO meter is suitable for rubbers less than 20 Shore A, whilst the AM meter covers the normal Shore A range. As expected from its name, the meter in Part 2 of the standard covers the IRHD range. 

Establishes a system for designating cellular elastomeric materials based on natural, synthetic, or reclaimed rubber, or rubber-like materials, alone or in combination. Cellular ebonite (hard rubber) and rigid cellular plastics are not included. Revision B was issued 30 January 1968. Notice 1 makes this standard inactive for new design, which would thereafter refer to the applicable portions of ASTM D 1055, D 1056, D 1505, D 1667 and D 3574. Cross reference tables are given. 

Although hard-rubber containers had been used for many decades (Fig. 12.8), polypropylene (PP) containers and lids, manufactured by injection moulding, became standard from about the 1960s (Figs. 12.1, 12.5). Therefore, at the beginning of the 21st century, the standard SLI battery in a new car still uses the same... 

The hardness measured with the small pocket type of hardness meter is associated with the durometer tests. Although there is not an international standard [1] that covers durometers, there is one for plastics, ISO R868 [10], which was used [9]. The two durometers specified are the Shore A and D which are also described in ASTM D2240 [11] where they are intended to cover both rubbers and plastics. The A scale corresponds approximately to the IRHD (International Rubber Hardness Degrees) scale and the D scale can be conveniently be used for hard rubbers above about 90 IRHD. 

In principle any of the tests could be used to study crystallization of rubbers by conditioning the test pieces for much longer times than normal, but in practice the favored method is change in hardness, one reason being that unvulcanized materials can be tested. Because crystallization is more rapid in the strained state, a particular type of compression set test has also been standardized for rubbers. 

Lined carbon steel is the standard material of construction for primary pressure filter vessels. Typical linings are hard rubber, 3 or 6 mm thick, and glass-filled epoxy resins. Metallic internals tend to be Monel or titanium. Piping is FRP or a thermoplastic such as PVC wrapped with FRP for reinforcement. Internal piping, if not metal, may be of CPVC, properly supported. In larger sizes, support plates usually are of rubber-coated steel. 

Safety shoes — Have toe guards that meet testing requirements found in the American National Standards Institute (ANSI) consensus standard on protective footwear (mentioned above). Steel, reinforced plastic, and hard rubber are used for safety toes, depending on their intended use. 

Hard rubber HSP boxes High energy Standard cell Height Length Width ... 

The radiation and temperature dependent mechanical properties of viscoelastic materials (modulus and loss) are of great interest throughout the plastics, polymer, and rubber from initial design to routine production. There are a number of laboratory research instruments are available to determine these properties. All these hardness tests conducted on polymeric materials involve the penetration of the sample under consideration by loaded spheres or other geometric shapes [1]. Most of these tests are to some extent arbitrary because the penetration of an indenter into viscoelastic material increases with time. For example, standard durometer test (the "Shore A") is widely used to measure the static "hardness" or resistance to indentation. However, it does not measure basic material properties, and its results depend on the specimen geometry (it is difficult to make available the identity of the initial position of the devices on cylinder or spherical surfaces while measuring) and test conditions, and some arbitrary time must be selected to compare different materials. 

International Rubber Hardness. The International mbber hardness test (ASTM D1415) (2) for elastomers is similar to the Rockwell test ia that the measured property is the difference ia penetration of a standard steel ball between minor and major loads. The viscoelastic properties of elastomers require that a load appHcation time, usually 30 seconds, be a part of the test procedure. The hardness number is read directly on a scale of 0 to 100 upon return to the minor load. International mbber hardness numbers are often considered equivalent to Durometer hardness numbers but differences ia iadenters, loads, and test time preclude such a relationship. 

The apparently simple process of indentation involves deformations in tension, shear and compression but, as in the case of a perfectly elastic rubber the moduli controlling these are closely related, it is convenient to regard hardness as depending simply on Young s modulus. Approximate relationships for various geometries of indentor have been given in Section 1 and will be further considered, where appropriate, for the standard methods in later sections. 

For hardness above 95 and below 30 IRHD the normal standard method is not very satisfactory. In either case a very small change in hardness number results from unit change in indentation. At the high end the indentation needs to be increased relative to the standard test to give better discrimination and at the low end the indentation needs to be decreased to prevent excessive deformation of soft rubbers. 

The most straightforward way to measure the effect of low temperatures on recovery is by means of a compression set or tension set test. Tests in compression are favoured and a method has been standardised internationally. The procedure is essentially the same as set measurements at normal or elevated temperatures and has been discussed in Chapter 10, Section 3.1. As the recovery of the rubber becomes more sluggish with reduction of temperature the dynamic loss tangent becomes larger and the resilience lower (see Chapter 9), and these parameters are sensitive measures of the effects of low temperatures. Procedures have not been standardized, but rebound resilience tests are inherently simple and quite commonly carried out as a function of temperature. It is found that resilience becomes a minimum when the rubber is in its most leathery state and rises again as the rubber becomes hard and brittle. 

It would appear that the common standard low temperature tests are not thought totally suitable for measuring effects of crystallisation because a hardness tests has been standardised for this purpose, even although hardness tests are not so commonly used for measuring the immediate effect of low temperature. The international method ISO 338733 and the British method BS 903 Part A6334 are the same and are applicable to unvulcanised as well as vulcanised rubber. This is probably one reason why the hardness test has been introduced because the other methods would not be satisfactory... 

Standard test method for rubber property Durometer hardness Shore A and Shore D hardness testing of rubber Physical testing of rubber Part A57... 

To relate the physical properties of carbon black to rubber properties, we tested these tread blacks in the ASTM natural rubber recipe and in an SBR 1500 test recipe. In both elastomers, we checked standard stress/strain properties of modulus, tensile strength, and hardness. In the natural rubber recipe we also tested Firestone running temperature and rebound, and Goodyear rebound. In the SBR we checked percent swell, extrusion rate, viscosity, and laboratory abrasion. 

Materials. Two types of standard tire cord obtained from Gen Corporation were used in this investigation polyester, 1300/3, and nylon 66, 1260/3. The rubber composition to which the adhesively dipped cords were bonded had the following composition in parts by weight styrene-butadiene rubber (SBR) 1502, 100 N330 carbon black, 50 zinc oxide, 5 stearic acid, 0.5 sulfur, 1.7 2-morpholinothio-benzothiazole, 2. Master batches were mixed 7 min in a 350-ml Brabender Plasticorder, and curatives were added on a cool two-roll mill. Cure characteristics at 155 °C were determined with an oscillating disc rheometer (ASTM D 2084). The time to reach 90% of the final cure state was 23 min, and the Shore A hardness of the final vulcanizate was approximately 60. 

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