Designation standards: ASTM D7121-05(2018) Publication date standards: 1.6.2018 SKU: NS-856441 The number of pages: 4 Approximate weight : 12 g (0.03 lbs) Country: American technical standard Category:Technical standards ASTM
4.1 The Schob Type rebound pendulum is
designed to measure the percentage resilience of a rubber compound
as an indication of hysteretic energy loss that can also be defined
by the relationship between storage modulus and loss modulus. The
percent rebound measured is inversely proportional to the
hysteretic loss.
4.1.1 Percentage resilience or rebound
resilience are commonly used in quality control testing of polymers
and compounding chemicals.
4.1.2 Rebound resilience is determined by
a freely falling pendulum hammer that is dropped from a given
height that impacts a test specimen and imparts to it a certain
amount of energy. A portion of that energy is returned by the
specimen to the pendulum and may be measured by the extent to which
the pendulum rebounds, whereby the restoring force is determined by
gravity.
4.1.2.1 Since the energy of the pendulum
is proportional to the vertical component of the displacement of
the pendulum, it may be expressed as 1 – cos (of the angle of
displacement) and percentage rebound resilience. RB, commonly called percentage rebound,
is determined from the equation:
4.1.2.2 The rebound resilience may be
calculated as:
4.1.2.3 The rebound resilience may also
be determined by the measurement of the angle of rebound α. From
the rebound angle α, the rebound resilience in percent is obtained
according to the following formula:
1. Scope
1.1 This test method covers a means of
determining the resilience of rubber, within a range of impact
strain and strain rate, by means of the impacting and measuring
apparatus conforming to the requirements described in this test
method.
1.2 This test method is applicable to
thermoset rubbers and thermoplastic elastomers, the hardness of
which, at the specified test temperatures, lies between 30 and 85
IRHD (see Test Method D1415)
or A/30 and A/85 (see Test Method D2240). It may also be applicable to some
polyester, polyether foam, and plastic foam materials.
1.3 All materials, instruments, or
equipment used for the determination of mass, force, or dimension
shall have traceability to the National Institute for Standards and
Technology, or other internationally recognized organization
parallel in nature.
1.4 The values stated in SI units are to
be regarded as standard. The values given in parentheses are for
information only.
1.5This standard does not purport to
address all of the safety concerns, if any, associated with its
use. It is the responsibility of the user of this standard to
establish appropriate safety, health, and environmental practices
and determine the applicability of regulatory limitations prior to
use.
1.6This international standard was
developed in accordance with internationally recognized principles
on standardization established in the Decision on Principles for
the Development of International Standards, Guides and
Recommendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
Standard Practice for Rubber—Materials,
Equipment, and Procedures for Mixing Standard Compounds and
Preparing Standard Vulcanized Sheets (Includes all amendments and
changes 11/12/2021).
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