GB/T 12825-2003 PDF in English
GB/T 12825-2003 (GB/T12825-2003, GBT 12825-2003, GBT12825-2003)
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| GB/T 12825-2003 | English | 90 |
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polymeric materials, cellular flexible -- Determination of hardness by indentation technique
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| GB/T 12825-1991 | English | 199 |
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Polymeric materials, cellular flexible--Determination of hardness (indentation technique)
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Standards related to (historical): GB/T 12825-2003
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GB/T 12825-2003: PDF in English (GBT 12825-2003) GB/T 12825-2003
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.100
G 44
idt ISO 2439:1997
Polymeric materials, cellular flexible – Determination of
hardness by indentation technique
ISSUED ON: JANUARY 10, 2003
IMPLEMENTED ON: JULY 01, 2003
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the People’s Republic of China.
Table of Contents
Foreword ... 3
ISO Foreword ... 4
1 Scope ... 5
2 Normative references ... 5
3 Definition ... 6
4 Principle ... 6
5 Apparatus ... 6
6 Test pieces ... 7
7 Procedure ... 7
8 Repeat tests ... 9
9 Test report ... 9
Foreword
This Standard is identical to the revision of the National Standard GB/T 2825-1991,
Polymeric materials cellular flexible – Determination of hardness (indentation
technique) by adopting the International Standard ISO 2439:1997 Flexible cellular
polymeric materials – Determination of hardness (indentation technique).
Compared with GB/T 12825-1991, this Standard makes the following main technical
changes:
1) In 6.3 of this Standard, test pieces are permitted for testing at either 16 h or 48 h after
manufacture, provided that the mean result does not differ by more than +10%, while
in the original standard, tests are permitted only at 72 h after manufacture.
2) Delete three test conditions specified in sub-clause 6.3 “parking” of the original
standard.
This Standard replaces GB/T 12825-1991 since the date of implementation.
This Standard was proposed by the former State Petroleum and Chemical Industry
Bureau.
This Standard shall be under the jurisdiction of National Technical Committee on
Rubber and Rubber Products Standardization, Sub-Technical Committee on Latex
Products.
Drafting organization of this Standard: China Rubber Group Zhuzhou Rubber and
Plastics Industry Research and Design Institute.
Main drafters of this Standard: Zhao Ping, Song Yanfei.
This Standard was first published in 1991.
Polymeric materials, cellular flexible – Determination of
hardness by indentation technique
WARNING: Persons using this Standard shall be familiar with normal laboratory
practice. This Standard does not purport to address all of the safety problems, if
any, associated with its use. It is the responsibility of the user to establish
appropriate safety and health practices and to ensure compliance with any
national regulatory conditions.
1 Scope
This Standard specifies three methods for determining the indentation, hardness of
flexible cellular materials:
method A (indentation hardness index), which gives a single indentation measurement
for laboratory test purposes;
method B (indentation hardness characteristics), which provides information about the
shape of the hardness indentation curve;
method C (indentation hardness check), which is a quick procedure suitable for quality
control testing.
This Standard is applicable only to latex, urethane foam and PVC foam of the open cell
type.
Note: The indentation hardness of flexible cellular materials is a measure of their load-
bearing properties. The methods specified can be used for testing finished
articles and for the characterization of bulk material.
The results obtained by these methods relate only to the test conditions specified and
cannot, in general, be used directly for design purposes.
2 Normative references
The following standard contains provisions which, through reference in this text,
constitute provisions of this Standard. At the time of publication, the edition indicated
was valid. All standards are subject to revision, and parties to agreements based on this
Standard are encouraged to investigate the possibility of applying the most recent
edition of the standard indicated below.
deflection, release the load at the same rate. Repeat this loading and unloading twice
more, then proceed in accordance with 7.2, 7.3 or 7.4 as appropriate.
7.2 Method A - Determination of indentation hardness index
Note the corresponding force, in newtons, according to the test method in 7.1, and
release the force.
Only the result of a test conducted by method A, on the standard size test piece, without
plying, shall be known as the indentation hardness index.
7.3 Method B - Determination of indentation hardness characteristics
Immediately after the third unloading (see 7.1), the following steps shall be carried out:
Indent the test piece by 25% ± 1% of the thickness; maintain this indentation for a
period of 30 s ± 1 s; measure the force;
Increase the indentation to 40% ± 1%; maintain this indentation for a period of 30 s ±
1 s; measure the force;
Increase the indentation to 65% ± 1% of the thickness; maintain this indentation for a
period of 30 s ± 1 s; measure the force.
The results of a test conducted by method B on a standard test piece shall be known as
the standard indentation hardness characteristics of that material. If a product is tested,
the results shall be known as the product indentation hardness characteristics.
Note: Convenient means of expressing the results obtained by method B are indentation
factors, which are the ratios of the forces required to obtain the indentation of 25 %
and 65% divided by the force required to obtain the indentation of 40%.
7.4 Method C - Determination of indentation hardness check
Immediately after the third unloading (see 7.1) start the autographic recording, or bring
back the tell-tale needle of the force gauge, and indent the test piece to 40% ± 1% of
the thickness. Record the force, in newtons, using the tell-tale needle or the
instantaneous maximum of the autographic recorder. Release the force.
The results of a test conducted by method C shall be known as the indentation hardness
check.
Note: This is a faster, quality-control test for indentation hardness. The variability of
results obtained in this way will be higher. It shall also be noted that the results
obtained in this way may be related to results obtained with method A but will
usually be higher.
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Translated by: Field Test Asia Pte. Ltd. (Incorporated & taxed in Singapore. Tax ID: 201302277C)
Linkin: https://www.linkedin.com/in/waynezhengwenrui/
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Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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