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GB/T 1634 Plastics - Determination of temperature of deflection under load consists of the following three parts:
—— Part 1: General test method;
—— Part 2: Plastics and ebonite;
—— Part3: High-strength thermosetting laminates.
This is Part 2 of GB/T 1634.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 1634.2-2004 Plastics - Determination of temperature of deflection under load - Part 2: Plastics, ebonite and long-fiber-reinforced composites. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 1634.2-2004:
—— testing in the edgewise position is deleted (see Annex A of Edition 2004);
—— precision is modified (see Annex A of this standard and Annex B of Edition 2004),
This part has been redrafted and modified in relation to ISO 75-2: 2013 Plastics - Determination of temperature of deflection under load - Part 2: Plastics and ebonite. The main technical differences with respect to ISO 75-2: 2013 are as follows:
—— The adjustments of technical differences are made for the normative references in this standard so as to adapt to the technical conditions of China. The adjustment is mainly reflected in clause 2 "Normative reference", with the specific adjustments as follows:
ISO 75-1 is replaced by GB/T 1634.1-2019 which is modified in relation to the international standard;
ISO 293 is replaced by GB/T 9352-2008 which is identical to the international standard;
ISO 294-1 is replaced by GB/T 17037.1-1997 which is identical to the international standard;
ISO 20753 is replaced by GB/T 37426-2019, which is modified in relation to the international standard;
Undated ISO 2818 is replaced by dated ISO 2818: 1994;
Undated ISO 10724-1 is replaced by dated ISO 10724-1: 1998.
The following editorial changes have been made in this part:
—— the Introduction is modified;
—— Annex A is modified, and precision data tested in Chinese laboratories is added.
This part was proposed by China Petroleum and Chemical Industry Association.
This part was prepared by SAC/TC 15 National Technical Committee on Plastic of Standardization Administration of China.
The previous edition replaced by this part is as follows:
——— GB/T 1634.2-2004.
Introduction
The first edition of GB/T 1634.1 and this part of GB/T 1634 described three methods (A, B and C) using different test loads and two specimen positions, edgewise and flatwise. For testing in the flatwise position, test specimens with dimensions 80 mm x 10 mm x 4 mm were required. These can be moulded directly or machined from the central section of the multipurpose test specimen (see ISO 20753).
The previous (i.e. second) edition of GB/T 1634.1 and this part of GB/T 1634 specified the flatwise test position as preferred, while still allowing testing in the edgewise position with test conditions. With this revision, the edgewise test position will be removed.
Technical development of testing instruments made instruments based on a fluidized bed or air ovens available. These are especially advantageous for use at temperatures at which the common silicone oil-based heat transfer fluids reach their limit of thermal stability. The fluidized bed and air oven methods of heat transfer are introduced in GB/T 1634.1.
Plastics - Determination of temperature of deflection under load -
Part 2: Plastics and ebonite
1 Scope
This part of GB/T 1634 specifies three methods, using different values of constant flexural stress, which can be used for the determination of the temperature of deflection under load of plastics (including filled plastics and fiber-reinforced plastics in which the fiber length, prior to processing, is up to 7.5 mm) and ebonite.
—— method A, using a flexural stress of 1.80 MPa;
—— method B, using a flexural stress of 0.45 MPa;
—— method C, using a flexural stress of 8.00 MPa.
The standard deflection, Δs, used to determine the temperature of deflection under load corresponds to a flexural-strain increase, Δεf, defined in this part. The initial flexural strain due to the loading of the specimen at room temperature is neither specified nor measured in this part. The ratio of this flexural-strain increase to the initial flexural strain depends on the modulus of elasticity, at room temperature, of the material under test. This method is, therefore, only suitable for comparing the temperatures of deflection of materials with similar room-temperature elastic properties.
Note 1: The methods give better reproducibility with amorphous plastics than with semi-crystalline ones. With some materials, it can be necessary to anneal the test specimens to obtain reliable results. Annealing procedures, if used, generally result in an increase in the temperature of deflection under load (see 6.6).
Note 2: For additional information, see GB/T 1634.1-2019, clause 1.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 1634.1-2019 Plastics - Determination of temperature of deflection under load - Part 1: General test method (ISO 75-1: 2013, MOD)
GB/T 9352-2008 Plastics - Compression moulding of test specimens of thermoplastic materials (ISO 293: 2004, IDT)
GB/T 17037.1-1997 Plastics - Injection moulding of test specimens of thermoplastic materials - Part 1: General principles and moulding of multipurpose and bar test specimens (ISO 294-1: 1996, IDT)
GB/T 37426-2019 Plastics - Test specimens (ISO 20753: 2008, MOD)
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 principles and moulding of multipurpose test specimens.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 1634.1-2019 apply.
Note: Depending on the selected value of the flexural stress (see clause 1), the temperature of deflection under load (see definition 3.7 in GB/T 1634.1-2019) is designated as Tf 0.45, Tf 1.8 or Tf 8.0.
4 Principle
The principle is specified in GB/T 1634.1-2019, clause 4.
5 Apparatus
5.1 Means of producing a flexural stress
This is specified in GB/T 1634.1-2019, 5.1.
The span (distance between the lines of contact between specimen and supports) shall be (64 ± 1) mm for testing.
5.2 Heating equipment
This is specified in GB/T 1634.1-2019, 5.2.
5.3 Weights
This is specified in GB/T 1634.1-2019, 5.3.
5.4 Temperature-measuring instrument
This is specified in GB/T 1634.1-2019, 5.4.
5.5 Deflection-measuring instrument
This is specified in GB/T 1634.1-2019, 5.5.
6 Test specimens
6.1 General
This is specified in GB/T 1634.1-2019, 6.1.
6.2 Shape and dimensions
This is specified in GB/T 1634.1-2019, 6.2. The preferred test-specimen dimensions are: length l: (80 ± 2.0) mm; width b: (10 ± 0.2) mm; thickness h: (4 ± 0.2) mm.
6.3 Specimen inspection
This is specified in GB/T 1634.1-2019, 6.3.
6.4 Number of test specimens
This is specified in GB/T 1634.1-2019, 6.4.
6.5 Test-specimen preparation
Test specimens shall be produced in accordance with GB/T 9352-2008 (or ISO 2818: 1994, if applicable), or in accordance with GB/T 17037.1-1997 or ISO 10724-1: 1998, or as agreed by the interested parties. The test results obtained on moulded test specimens depend on the moulding conditions used in their preparation. The moulding conditions shall be in accordance with the standard for the material concerned, or as agreed by the interested parties.
In the case of compression-moulded specimens, the thickness shall be in the direction of the moulding force. For materials in sheet form, the thickness of the test specimens (this dimension is usually the thickness of the sheet) shall be in the range 3 mm to 13 mm, preferably between 4 mm to 6 mm.
The specimen may be taken from the narrow central part of the multipurpose test specimen specified in GB/T 37426-2019 (specimen type A1).
6.6 Annealing
Discrepancies in test results due to variations in moulding conditions may be minimized by annealing the test specimens before testing them. Since different materials require different annealing conditions, annealing procedures shall be employed only if required by the materials standard or if agreed upon by the interested parties.
Foreword i
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Test specimens
7 Conditioning
8 Procedure
9 Expression of results
10 Precision
11 Test report
Annex A (Informative) Precision
Bibliography
