GB/T 9341-2008 English PDF (GBT9341-2008)

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GB/T 9341-2008: Plastics -- Determination of flexural properties
GB/T 9341-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.080.01
G 31
GB/T 9341-2008 / ISO 178.2001
Replacing GB/T 9341-2000
Plastics - Determination of flexural properties
(ISO 178.2001, IDT)
ISSUED ON. AUGUST 4, 2008
IMPLEMENTED ON. APRIL 1, 2009
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration Committee.
Table of Contents
Foreword ... 3 
ISO Foreword ... 5 
1 Scope ... 6 
2 Normative references ... 7 
3 Terms and definitions ... 8 
4 Principle... 10 
5 Test machine ... 10 
6 Test specimens ... 12 
7 Conditioning ... 16 
8 Procedure ... 16 
9 Calculation and expression of results ... 18 
10 Precision ... 21 
11 Test report ... 21 
Annex A ... 22 
Annex B ... 24 
Bibliography ... 26 
Foreword
This Standard is identical with ISO 178.2001 Plastics - Determination of flexural
properties. This Standard has incorporated, the content of No. 1 Amendment of
ISO/TC 61/SC issued in 2004, into the text.
Compared with GB/T 9341-2000, the main changes are as follows.
- Deleted the fiber-reinforced thermosetting and thermoplastic composites,
thermotropic liquid crystal polymer in Scope;
- Added the definition of “rigid plastic”;
- Revised the requirements for balance between supports and loading
edge;
- Deleted the requirements for some measuring instruments;
- Revised the requirements for non-recommended sample size;
- Added the number of injection sample;
- Stipulated the preferred conditions for state regulation;
- Revised the provisions on corresponding excluding sample;
- Added the requirements for initial stress in test;
- Added the calculation method for flexural strain;
- Added Annex A “Compliance correction”;
- Added Annex B “Precision statement”.
Annex A of this Standard is normative; Annex B is informative.
This Part was proposed by China Petroleum and Chemical Industry Federation.
This Part shall be under the jurisdiction of National Technical Committee on
Plastics of Standardization Administration of China (SAC/TC 15).
Main drafting organization of this Standard. Sinopec National Test Center of
Polymer and Building Materials.
The drafting organizations of this Standard. Guangzhou Institute of Synthetic
Materials Limited, National Quality Supervision and Inspection Center of
Synthetic Resin, Beijing Yanshan Petrochemical Resin Institute, National
Plastics - Determination of flexural properties
1 Scope
1.1 This Standard specifies a method for determining the flexural properties
of rigid and semi-rigid plastics under defined conditions. A standard test
specimen is defined, but parameters are included for alternative specimen sizes
for use where appropriate. A range of test speeds is included.
1.2 The method is used to investigate the flexural behavior[1] of the test
specimens and for determining the flexural strength, flexural modulus and other
aspects of the flexural stress/strain relationship under the conditions defined. It
applies to a freely supported beam, loaded at midspan (three-point loading test).
1.3 The Standard is suitable for use with the following range of materials.
- thermoplastics moulding and extrusion materials, including filled and
reinforced compounds in addition to unfilled types; rigid thermoplastics
sheets;
- thermosetting moulding materials, including filled and reinforced
compounds; thermosetting sheets.
In agreement with GB/T 19467.1-2004[2] and GB/T 19467.2-2004[3], this
Standard applies to fiber-reinforced compounds with fiber lengths ≤7.5 mm prior
to processing. For long-fiber-reinforced materials (laminates) with fiber lengths >
7.5 mm, see reference[4] in the bibliography.
The method is not normally suitable for use with rigid cellular materials and
sandwich structures containing cellular material [5, 6].
NOTE. For certain types of textile-fiber-reinforced plastics, a four-point bending test is
preferred. It is described in reference[4].
1.4 The method is performed using specimens which may be moulded to the
specified dimensions, machined from the central portion of a standard
multipurpose test specimen (see GB/T 11997-2008) or machined from finished
or semi-finished products such as mouldings, or extruded or cast sheet.
1.5 The method specifies preferred dimensions for the test specimen. Tests
which are carried out on specimens of different dimensions, or on specimens
which are prepared under different conditions, may produce results which are
not comparable. Other factors, such as the test speed and the conditioning of
the specimens, can also influence the results. Especially for semi-crystalline
polymers, the thickness of the oriented skin layer, which is dependent on
moulding conditions and thickness, affects the flexural properties.
Consequently, when comparable data are required, these factors must be
carefully controlled and recorded.
1.6 Flexural properties can only be used for engineering design purposes for
materials with linear stress/strain behavior. For non-linear behavior, the flexural
properties are only nominal. The bending test should preferentially be used with
brittle materials, for which tensile tests are difficult.
2 Normative references
The following standards contain the provisions which, through reference in this
Standard, constitute the provisions of this Standard. For dated references,
subsequent amendments (excluding corrections) or revisions do not apply to
this Standard. However, the parties who enter into agreement based on this
Standard are encouraged to investigate whether the latest versions of these
documents are applicable. For undated reference documents, the latest
versions apply to this Standard.
GB/T 2918-1998 Plastics - Standard atmospheres for conditioning and
testing (idt ISO 291.1997)
GB/T 5471-2008 Plastics - Compression moulding of test specimens of
thermosetting materials (ISO 295.2004, IDT)
GB/T 9352-2008 Plastic - Compression moulding of test specimens of
thermoplastic materials (ISO 293.2004, IDT)
GB/T 11997-2008 Plastic - Multipurpose test specimens (ISO 37.2002, IDT)
GB/T 17037.1-1997 Injection moulding of test specimens of thermoplastic
materials - Part 1. General principles and moulding of multipurpose and bar
test specimens (idt ISO 294-1.1996)
GB/T 17200-1997 Technical specification for tensile compression and
flexural testing machines for rubber and plastics (idt ISO 5893.1993)
ISO 2602.1980 Statistical interpretation of test results - Estimation of the
mean - Confidence interval
ISO 2818.1994 Plastics - Preparation of test specimens by machining
ISO 10724-1.1998 Plastics - Injection moulding of test specimens of
thermosetting powder moulding compounds (PMCs) - Part 1. General
Bibliography
[1] GB/T 1040.1-2006 Plastics - Determination of tensile properties - Part 1.
General principles (ISO 527-1.1993, IDT)
[2] GB/T 19467.1-2004 Plastics - Acquisition and presentation of
comparable single-point data - Part 1.Moulding materials (ISO 10350-
1.1998, MOD)
[3] GB/T 19467.2-2004 Plastics - Acquisition and presentation of
comparable single-point data - Part 2.Long-fiber-reinforced plastics (ISO
10350-2.2001, IDT)
[4] GB/T 1449-2005 Fiber-reinforced Plastic Composites - Determination of
Flexural Properties (ISO 14125.1998, NEQ)
[5] GB/T 8812.1-2007 Rigid cellular plastics - Determination of flexural
properties - Part 1. Basic bending test (ISO 1209-1.2004, IDT)
[6] GB/T 8812.2-2007 Rigid cellular plastics - Determination of flexural
properties - Part 2.Determination of flexural strength and apparent flexural
modulus of elasticity (ISO 1209-2.2004, IDT)
[7] GB/T 2035-2008 Terms and definitions for plastics (ISO 472.1999, IDT)