Rubber resilience tests

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. 

FIGURE 9.16 Resilience values for chlorobutyl rubber (CIIR), butadiene rubber (BR), unfilled natural rubber (NR), filled natural rubber (SRB), and polyurethane (PU) samples tested using a Shore rebound resibometer, an Instron compression tester and a scanning probe microscope (SPM). (From Huson, M.G. and Maxweb, J.M.,... 

An instrument for measuring the resilience of rubber by dropping a flattened steel cone vertically on the test piece and measuring the rebound. 

ASTM D1054 Standard test method for rubber property-resilience using a Goodyear-Healey rebound pendulum... 

ASTM D2632 (tailing weight) Standard test method for rubber property Resilience by vertical rebound... 

Compression set is commonly used as a measure of the dimensional recovery of a rubber compound after compression at a defined level, usually 25%, at a specified time and temperature, usually 24 h at 70°C. High compression set values are associated with rubber that takes a set or loses its ability to spring back after compression. Low compression set is important for rubber closures and syringe plungers that are heat sterilized while under compression and remain under compression for long periods of time before use but must remain elastic and resilient to maintain seal integrity. Compression Set is measured on dimensionally defined test specimens. 

ASTM D 1054-87 Standard Test Method for Rubber Property — Resilience Using a Rebound Pendulum, 6 pp (DOD Adopted) (FSC 9320) (MR) (Comm D-11)... 

The Yerzley Oscillograph (ASTM D945) has been used for rubber testing by monitoring the decay of the sample subjected to a dynamic oscillation by a cantilever. Terms such as Yerzley hysteresis and resilience seem peculiar to this apparatus, and since large deformations were necessary, the nonlinearity suggests that only an average modulus could be obtained. 

Standard Test Method for Rubber Property-Resilience by Vertical Rebound. 

Resilience ri- zil-yan(t)s n (1824) (1) The degree to which a hody can quickly resume its original shape after removal of a deforming stress. When the body is a standard test specimen, the resilience, expressed as the percentage recovery from a stated maximum strain, may be attributed to the material from which R the specimen was made. ASTM Tests D 926 and D 945 (section 09.01) describes compression and shear tests for resilience of rubber and foam rubber. 

The addition of a thermoplastic rubber at 10-30 %w produces a truly thermoplastic product with elasticity, resilience, and high adhesive strength. Such mixtures can form the basis for a variety of sealants as discussed in the section on permanent crosslinking. Although the selection of the asphalt and its modifications with aromatic or paraffinic oils is not simple, a balance between resistance to phase separation at 300 F and the formation of a coherent network at ambient temperatures can be obtained by empirical tests. 

Elastomers are polymers with rubberlike properties. The word elastic refers to the ability of a material to return to its original dimensions when unloaded, and the term mer refers to the polymeric molecular make up in the word elastomer. Vulcanized rubber materials typically have more than 200% elongation in a tensile test and are capable of returning rapidly and forcibly to their original dimensions when load is removed. This elastic response is due to the three-dimensional cross-linked network molecular structure they have. An elastomer, on the other hand, typically has elongation rates of 100% or more and a significant amount of resilience. Resilience is represented by the area under the elastic portion of the stress-strain curve, and therefore, refers to a material s ability to undergo elastic deformations. 

Creep and creep recovery (resiliency) of RAC s are directly dependent upon the rubber content. These tests may be the most effective method for assessing the rubber/asphalt interactions. 

European standards " describe measurement of dynamic coeificient of friction on dry floor surfaces and determination of slip resistance by pendulum tester on natural stone.Measurement of dynamic coefficient of friction is done on a surface of resilient laminate and textile floor covering. Sliders are loaded with weights of 2 to 7 kg. They are pulled on a floor covering. The force required to pull slider is recorded and it is divided by the load to obtain dynamic coefficient of friction. " Stones intended to be used for flooring in buildings are tested by shd-ing of the standard rubber attached to the end of the pendulum. The frictional force is measured by deflection of pendulum. The slip resistance value is read from a scale.Pendulum tester is also used to determined slipperiness of floor according to Japanese standard. Slipperiness of floor panels is tested by separate method. ... 

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