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ICS 83. 080. 01
National Standard of the People's Republic of China
GB/T 9341—2000
idtIS0178:1993
Test method for flexural properties of plastics
Plastics----Determination of flexural propertiesIssued on October 27, 2000
Implementation from May 1, 2001
Issued by the State Administration of Quality and Technical Supervision
GB/T9341—2000
This standard is equivalent to the international standard IS0178:1993 "Plastics-Determination of flexural properties". Except for some editorial changes, the technical content is completely consistent with ISO178:1993. There are the following differences in editing: the reference standards of this standard are less than those specified in ISO178:1993, but the contents not included in this standard do not affect the implementation of this standard; a small number of editorial changes have been made according to relevant regulations of my country. The previous version of this standard is the national standard GB/T9341-1988 "Test method for bending properties of plastics". Compared with the previous version, the main technical differences are as follows: - the scope of application of the standard has been expanded; - reference standards have been added; - the specimen size and its deviation are different; - related terms and their definitions have been added; - the calculation method of modulus is different; - the indication accuracy of measuring instruments has been improved; and the content of test report records has been added. This standard will replace GB/T9341-1988 from the date of implementation. This standard is proposed by the State Administration of Petroleum and Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Plastic Resin Products Branch of the National Technical Committee for Plastic Standardization (TC15/SC4). The main drafting units of this standard are: Shanghai Plastics Research Institute, Shanghai Commodity Inspection Bureau. The participating drafting units of this standard are: Chenguang Chemical Research Institute, Beijing Yanshan Petrochemical Resin Institute, Jilin University Science and Education Instrument Factory, Chengde Material Testing Machine Factory, Beijing Chemical Research Institute, Changchun Testing Machine Institute, Shanghai Material Institute, Dalian Plastics Research Institute, Daqing Petrochemical General Plant, Shanghai Petrochemical Plastics Factory, Shanghai Gaoqiao Chemical Plant, Liaohua No. 3 Plant, Shanghai Shengde Plastics Factory. The main drafters of this standard are: Shu Xingdao, Luo Taiwei, Li Jianghai, Shen Hong, Jiang Junning, Tai Yuxing, Zhao Lingyun. This standard was first issued in 1979 (GB/T1042-1979), and was revised for the first time in 1988 (GB/T9341-1988). This is the second revision.
GB/T9341-2000
ISO Foreword
The International Organization for Standardization (ISO) is a worldwide federation of national standardization bodies (ISO member bodies). The work of formulating international standards is generally carried out through ISO technical committees. Any member body interested in a project established by a technical committee has the right to send representatives to participate in the technical committee. Governmental or non-governmental international organizations can also participate in this work by contacting ISO. ISO and the International Electrotechnical Commission (IEC) work closely on all topics of electrotechnical standardization. The draft international standard adopted by the technical committee shall be submitted to the member bodies for voting before being accepted as an international standard. Only when at least 75% of the member bodies express their approval can it be published as a formal international standard. International standard ISO178 was formulated by ISO/TC61 Plastics Technical Committee, SC2 Mechanical Properties Technical Committee. This third edition replaces the second edition (ISO 178: 1975) and incorporates the following amendments: - Standard references have been added, in particular the preparation of test specimens and the use of multi-purpose test specimens in accordance with ISO 3167; - A definition of modulus has been given;
Only one strain rate has been recommended;
- The parameter nomenclature has been harmonized with other international standards for testing plastics in accordance with ISO 31. 1 Scope
National Standard of the People's Republic of China
Test method for flexural properties of plastics
Plastics--Determination of flexural propertiesGB/T 9341-2000
idt ISO 178: 1993
Replaces GB/T 9341--1988
1.1 This standard specifies a method for determining the flexural properties of plastics under specified conditions, specifies standard test specimens, and also provides dimensional parameters and test speed ranges for alternative test specimens suitable for use. 1.2 This method is used to study the bending properties of specimens under specified conditions and to determine the bending strength, bending modulus, and bending stress-strain relationship. This method is applicable to tests with free support at both ends and central loading (three-point loading test). 1.3 This method is applicable to the following materials:
-Thermoplastic molding and extrusion materials, including filled and reinforced unfilled materials and rigid thermoplastic sheets; thermosetting molding materials, including filled and reinforced materials, thermosetting sheets, including laminates; fiber-reinforced thermosetting and thermoplastic composites, which contain unidirectional or non-unidirectional reinforcement materials such as felt, textile fibers, textile rovings, chopped strands, combined or hybrid reinforcement materials, rovings and milled fibers; sheets made of prepreg materials; thermotropic liquid crystal polymers.
This method is generally not applicable to rigid microporous materials and sandwich structures containing microporous materials. Note 1: For some textile fiber reinforced plastics, it is best to use a four-point bending test. 1.4 The test specimens used in this method may be molded specimens of selected dimensions, specimens machined from the center of a standard multipurpose specimen, or specimens machined from finished or semi-finished products such as molded parts, laminates, extruded or cast sheets. 1.5 This method specifies the optimum specimen dimensions. Tests using specimens of different dimensions or prepared under different conditions will not give comparable results. Other factors, such as test speed and specimen conditioning, may also affect the test results. Therefore, these factors must be carefully controlled and recorded when data comparisons are required.
1.6 Only materials with linear stress-strain characteristics can be used as a basis for engineering design, and the bending properties of nonlinear materials are only nominal values. For brittle materials, that is, materials that are difficult to test in tension, the bending test is preferred. 2 Referenced Standards\)
The following standards contain provisions that, by reference in this standard, constitute provisions of this standard. The versions shown are valid at the time of publication. All standards are subject to revision, and parties using this standard should investigate the possibility of using the most recent versions of the following standards. GB/T2918-1998 Standard environment for conditioning and testing of plastic specimens (idtISO291:1997) GB/T3360-1982 Statistical processing and interpretation of data - Estimation and confidence interval of the mean (neqISO2602:1980) GB/T9352-1988 Preparation of compression specimens of thermoplastics (neqISO293:1986) GB/T17037.1--1997 Preparation of injection molding specimens of thermoplastic materials - Part 1: General principles and preparation of multi-purpose specimens and long strip specimens (idtISO294.1:1996) ISO 295:1991
Plastics - Compression molding specimens of thermosetting materials 1) The translation of the international standards cited in this standard shall be based on the version of the National Technical Committee for Plastics Standardization. Approved by the State Administration of Quality and Technical Supervision on October 27, 2000 and implemented on May 1, 2001
GB/T9341-2000
ISO1209-1:1990 Rigid microcellular plastics--Flexure test--Part 1: Flexure test ISO 1209-2:1990
Rigid microcellular plastics--Flexure test--Part 2: Determination of flexural properties Plastics--Preparation of glass-fibre reinforced, resin-bonded low-pressure laminated sheets or strips for testing ISO 1268:1974
ISO2557-1:1989 Plastics--Amorphous thermoplastics--Preparation of test specimens with a specified maximum recovery--Part 1: Strips
ISO 2557-2:1986
Plastics — Amorphous thermoplastics — Preparation of test specimens with specified maximum recovery — Part 2: Plates
ISO 2818:1994
Plastics — Preparation of test specimens by mechanical processingISO 3167:1993
Plastics — Multipurpose test specimens
3 Definitions
The following definitions apply to this standard.
3.1 Speed of testing, u The rate of relative movement between the support and the indenter, in mm/min. 3.2 Flexural stress dt The normal stress on the outer surface of the center of the span of the specimen, calculated according to formula (3) of 9.1, in MPa. 3.3 Flexural stress at break, oB Flexural stress at break of the specimen (see curves a and b in Figure 1), in MPa. 3.4 Flexural strength, om Maximum flexural stress to which the specimen is subjected during bending (see curves a and b in Figure 1), in MPa. 3.5 Flexural stress at conventional deflection, dfe Flexural stress when the deflection s specified in 3.7 is reached (see curve C in Figure 1), in MPa. 3.6 Deflection, s
The distance that the top or bottom surface of the specimen's span center deviates from its original position during bending, in mm. 3.7 Conventional deflection, s The specified deflection is 1.5 times the specimen thickness h, in mm. When the span L = 16h, the specified deflection is equivalent to a bending strain of 3.5% (see 3.8).
3.8Flexural strain, EtThe slight change in unit length on the outer surface of the specimen at the center of the span, expressed as a dimensionless ratio or percentage (%). Calculated according to equation (4) in 9.2.
3.9Flexural strain at break, EBThe bending strain at the time of specimen fracture (see curves a and b in Figure 1). Expressed as a dimensionless ratio or percentage (%). 3.10Flexural strain at flexural strength, EmThe bending strain at maximum bending stress (see curves a and b in Figure 1). Expressed as a dimensionless ratio or percentage (%). 3.11Modulus of elasticity in flexure; flexure tmodulus, E, the ratio of the stress difference at2-0f to the corresponding strain difference [(ef2=0.0025)-(ef=0.0005) [see equation (5) in 9.2, unit: MPa. Note 2: The bending modulus is only an approximation of the Young's modulus of elasticity. Note 3: The modulus E can be determined by computer using two different stress/strain points, that is, the curve between these two points is expressed after linear regression. 2
GB/T9341-2000
Curve a - the specimen breaks before yielding;
Curve b - the specimen breaks after showing the maximum value before the specified deflection $.; Curve ℃ - the specimen neither yields nor breaks before the specified deflection $. Typical curve of bending stress as a function of bending strain and deflection s Figure 1
The specimen is supported as a beam and bent at a constant speed at the center of the span until the specimen breaks or the deformation reaches a predetermined value, and the pressure applied to the specimen during this process is measured.
5 Equipment
5.1 Testing machine
5.1.1 Overview
The testing machine shall comply with the requirements of 5.1.2 to 5.1.4. 5.1.2 Test speed
The testing machine shall have the test speed specified in Table 1. Table 1
Speed, mm/min
Recommended test speed
1) For specimens with a thickness between 1 mm and 3.5 mm, use the lowest speed 5.1.3 Supports and indenters
GB/T 9341—2000
The positions of the two supports and the center indenter are shown in Figure 2. The parallelism between the supports and the indenter shall be within ±0.02 mm. The dimensions of the indenter radius R, and the support radius Rz are as follows: R,=5.0mm±0.1mm
R,=2.0mm±0.2mm, specimen thickness ≤3mmRz=5.0mm±0.2mm, specimen thickness>3mmThe span L shall be adjustable.
Applied force F
Figure 2 Position of specimen at the start of the test
5.1.4 Load and deflection indicators
The error of the indication of force shall not exceed 1%, and the error of the indication of deflection shall not exceed 1% of the full scale. 5.2 Micrometer and gauge
5.2.1 Micrometer, or equivalent measuring tool, with an accuracy of at least 0.01 mm (for measuring the specimen thickness h and width 6, see Figure 3). 5.2.2 A vernier caliper, or equivalent measuring tool, with an accuracy of within ±0.1% of the distance L, shall be used to measure the span (see 8.2 and Figure 2). Product
Length direction
Product width direction
Test specimen position
Product direction
Direction of applied force
Figure 3 Test specimen position relative to product direction and direction of applied force 6 Test specimen
6.1 Shape and size
6.1.1 Overview
GB/T 9341—2000
The test specimen size shall comply with the relevant material standards and, if applicable, shall comply with the requirements of 6.1.2 or 6.1.3. Otherwise, the type of test specimen must be negotiated with the relevant parties.
6.1.2 Recommended test specimens
The recommended test specimen dimensions are (in mm): length l = 80 ± 2
width 6 = 10.0 ± 0.2
thickness h = 4.0 ± 0.2
For any test specimen, the thickness of each point within the length of the middle 1/3 shall not deviate from the average thickness by more than 2%, and the corresponding width shall not deviate by more than 3%. The test specimen cross section shall be rectangular and without chamfers. NOTE 4: The recommended test specimen may be machined from the middle of a multi-purpose test specimen prepared in accordance with ISO 3167. 6.1.3 Other test specimens
When it is not possible or desirable to use the recommended test specimens, the following requirements shall be met. The ratio of the test specimen length to thickness shall be the same as that of the recommended test specimen, as given by formula (1): l/h = 20 ± 1
Test specimens provided in accordance with 8.2a), 8.2b) or 8.2c) are not subject to this restriction. (1
Note 5: When some product specifications require that specimens be made from plates with a thickness greater than the specified upper limit, machining methods can be used to machine only one side to the standard thickness. At this time, the unmachined surface of the specimen is usually in contact with two supports, and the center pressure head applies force to the machined surface of the specimen. The specimen width should use the specified values given in Table 2. Table 2 Width values related to thickness 6
Nominal thickness hWww.bzxZ.net
32 of formula (5), unit MPa. Note 2: The bending modulus is only an approximation of the Young's modulus of elasticity. Note 3: The modulus E can be determined by computer using two different stress/strain points, that is, the curve between these two points is processed by linear regression and then expressed. 2
GB/T9341-2000
Curve a - the specimen breaks before yielding;
Curve b - the specimen breaks after showing the maximum value before the specified deflection $.; Curve ℃ - the specimen neither yields nor breaks before the specified deflection $. Typical curve of bending stress changing with bending strain and deflection s Figure 1
The specimen is supported as a beam and bent at a constant speed at the center of the span until the specimen breaks or the deformation reaches a predetermined value, and the pressure applied to the specimen during the process is measured.
5 Equipment
5.1 Testing machine
5.1.1 Overview
The testing machine shall comply with the requirements of 5.1.2 to 5.1.4. 5.1.2 Test speed
The testing machine shall have the test speed specified in Table 1. Table 1
Speed, mm/min
Recommended test speed
1) For specimens with a thickness between 1 mm and 3.5 mm, use the lowest speed 5.1.3 Supports and indenters
GB/T 9341—2000
The positions of the two supports and the center indenter are shown in Figure 2. The parallelism between the supports and the indenter shall be within ±0.02 mm. The dimensions of the indenter radius R, and the support radius Rz are as follows: R,=5.0mm±0.1mm
R,=2.0mm±0.2mm, specimen thickness ≤3mmRz=5.0mm±0.2mm, specimen thickness>3mmThe span L shall be adjustable.
Applied force F
Figure 2 Position of specimen at the start of the test
5.1.4 Load and deflection indicators
The error of the indication of force shall not exceed 1%, and the error of the indication of deflection shall not exceed 1% of the full scale. 5.2 Micrometer and gauge
5.2.1 Micrometer, or equivalent measuring tool, with an accuracy of at least 0.01 mm (for measuring the specimen thickness h and width 6, see Figure 3). 5.2.2 A vernier caliper, or equivalent measuring tool, with an accuracy of within ±0.1% of the distance L, shall be used to measure the span (see 8.2 and Figure 2). Product
Length direction
Product width direction
Test specimen position
Product direction
Direction of applied force
Figure 3 Test specimen position relative to product direction and direction of applied force 6 Test specimen
6.1 Shape and size
6.1.1 Overview
GB/T 9341—2000
The test specimen size shall comply with the relevant material standards and, if applicable, shall comply with the requirements of 6.1.2 or 6.1.3. Otherwise, the type of test specimen must be negotiated with the relevant parties.
6.1.2 Recommended test specimens
The recommended test specimen dimensions are (in mm): length l = 80 ± 2
width 6 = 10.0 ± 0.2
thickness h = 4.0 ± 0.2
For any test specimen, the thickness of each point within the length of the middle 1/3 shall not deviate from the average thickness by more than 2%, and the corresponding width shall not deviate by more than 3%. The test specimen cross section shall be rectangular and without chamfers. NOTE 4: The recommended test specimen may be machined from the middle of a multi-purpose test specimen prepared in accordance with ISO 3167. 6.1.3 Other test specimens
When it is not possible or desirable to use the recommended test specimens, the following requirements shall be met. The ratio of the test specimen length to thickness shall be the same as that of the recommended test specimen, as given by formula (1): l/h = 20 ± 1
Test specimens provided in accordance with 8.2a), 8.2b) or 8.2c) are not subject to this restriction. (1
Note 5: When some product specifications require that specimens be made from plates with a thickness greater than the specified upper limit, machining methods can be used to machine only one side to the standard thickness. At this time, the unmachined surface of the specimen is usually in contact with two supports, and the center pressure head applies force to the machined surface of the specimen. The specimen width should use the specified values given in Table 2. Table 2 Width values related to thickness 6
Nominal thickness h
32 of formula (5), unit MPa. Note 2: The bending modulus is only an approximation of the Young's modulus of elasticity. Note 3: The modulus E can be determined by computer using two different stress/strain points, that is, the curve between these two points is processed by linear regression and then expressed. 2
GB/T9341-2000
Curve a - the specimen breaks before yielding;
Curve b - the specimen breaks after showing the maximum value before the specified deflection $.; Curve ℃ - the specimen neither yields nor breaks before the specified deflection $. Typical curve of bending stress changing with bending strain and deflection s Figure 1
The specimen is supported as a beam and bent at a constant speed at the center of the span until the specimen breaks or the deformation reaches a predetermined value, and the pressure applied to the specimen during the process is measured.
5 Equipment
5.1 Testing machine
5.1.1 Overview
The testing machine shall comply with the requirements of 5.1.2 to 5.1.4. 5.1.2 Test speed
The testing machine shall have the test speed specified in Table 1. Table 1
Speed, mm/min
Recommended test speed
1) For specimens with a thickness between 1 mm and 3.5 mm, use the lowest speed 5.1.3 Supports and indenters
GB/T 9341—2000
The positions of the two supports and the center indenter are shown in Figure 2. The parallelism between the supports and the indenter shall be within ±0.02 mm. The dimensions of the indenter radius R, and the support radius Rz are as follows: R,=5.0mm±0.1mm
R,=2.0mm±0.2mm, specimen thickness ≤3mmRz=5.0mm±0.2mm, specimen thickness>3mmThe span L shall be adjustable.
Applied force F
Figure 2 Position of specimen at the start of the test
5.1.4 Load and deflection indicators
The error of the indication of force shall not exceed 1%, and the error of the indication of deflection shall not exceed 1% of the full scale. 5.2 Micrometer and gauge
5.2.1 Micrometer, or equivalent measuring tool, with an accuracy of at least 0.01 mm (for measuring the specimen thickness h and width 6, see Figure 3). 5.2.2 A vernier caliper, or equivalent measuring tool, with an accuracy of within ±0.1% of the distance L, shall be used to measure the span (see 8.2 and Figure 2). Product
Length direction
Product width direction
Test specimen position
Product direction
Direction of applied force
Figure 3 Test specimen position relative to product direction and direction of applied force 6 Test specimen
6.1 Shape and size
6.1.1 Overview
GB/T 9341—2000
The test specimen size shall comply with the relevant material standards and, if applicable, shall comply with the requirements of 6.1.2 or 6.1.3. Otherwise, the type of test specimen must be negotiated with the relevant parties.
6.1.2 Recommended test specimens
The recommended test specimen dimensions are (in mm): length l = 80 ± 2
width 6 = 10.0 ± 0.2
thickness h = 4.0 ± 0.2
For any test specimen, the thickness of each point within the length of the middle 1/3 shall not deviate from the average thickness by more than 2%, and the corresponding width shall not deviate by more than 3%. The test specimen cross section shall be rectangular and without chamfers. NOTE 4: The recommended test specimen may be machined from the middle of a multi-purpose test specimen prepared in accordance with ISO 3167. 6.1.3 Other test specimens
When it is not possible or desirable to use the recommended test specimens, the following requirements shall be met. The ratio of the test specimen length to thickness shall be the same as that of the recommended test specimen, as given by formula (1): l/h = 20 ± 1
Test specimens provided in accordance with 8.2a), 8.2b) or 8.2c) are not subject to this restriction. (1
Note 5: When some product specifications require that specimens be made from plates with a thickness greater than the specified upper limit, machining methods can be used to machine only one side to the standard thickness. At this time, the unmachined surface of the specimen is usually in contact with two supports, and the center pressure head applies force to the machined surface of the specimen. The specimen width should use the specified values given in Table 2. Table 2 Width values related to thickness 6
Nominal thickness h
3
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