GB/T 1634.1-2019 PDF English
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Plastics -- Determination of temperature of deflection under load -- Part 1: General test method
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| GB/T 1634.1-2004 | English | 85 |
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Plastics -- Determination of temperature of deflection under load -- Part 1: General test method
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Test method of heat deflection temperature under bending load for plastics
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GB/T 1634.1-2019: PDF in English (GBT 1634.1-2019) GB/T 1634.1-2019
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.080.01
G 31
Replacing GB/T 1634.1-2004
Plastics - Determination of temperature of deflection
under load - Part 1: General test method
(ISO 75-1:2013, MOD)
ISSUED ON: MAY 10, 2019
IMPLEMENTED ON: APRIL 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 7
4 Principle ... 8
5 Apparatus ... 8
6 Test specimens ... 12
7 Conditioning ... 13
8 Procedure ... 13
9 Expression of results ... 16
10 Precision ... 16
11 Test report ... 16
Bibliography ... 18
Foreword
GB/T 1634 "Plastics - Determination of temperature of deflection under load" is
divided into 3 parts:
- Part 1: General test method;
- Part 2: Plastics and ebonite;
- Part 3: High-strength thermosetting laminates.
This Part is Part 1 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 1634.1-2004 "Plastics - Determination of temperature
of deflection under load - Part 1: General test method". Compared with GB/T
1634.1-2004, in addition to editorial modifications, the main technical changes
are as follows:
- Delete the edgewise test position;
- As for heating equipment, add fluidized bed and air oven;
- Modify the calculation formula for the mass of weights.
This Part uses redraft law to modify and adopt ISO 75-1:2013 "Plastics -
Determination of temperature of deflection under load - Part 1: General test
method".
The technical differences between this Part and ISO 75-1:2013 and their
reasons are as follows:
- As for the normative references, this Part has adjusted the technical
differences, to adapt to the technical conditions of China. The adjustments
are mainly reflected in Clause 2 “Normative references”. The specific
adjustments are as follows:
Replace ISO 75-2 with GB/T 1634.2 which modifies and adopts the
international standard;
Replace ISO 75-3 with GB/T 1634.3 which modifies and adopts the
international standard;
Replace ISO 291 with GB/T 2918 which modifies and adopts the
international standard;
Plastics - Determination of temperature of deflection
under load - Part 1: General test method
1 Scope
This Part of GB/T 1634 gives a test method for the determination of the
temperature of deflection under load (flexural stress under three-point loading)
of plastics. Different types of test specimen and different constant loads are
defined to suit different types of material.
GB/T 1634.2 gives specific requirements for plastics (including filled plastics
and fibre-reinforced plastics in which the fibre length is up to 7.5 mm) and
ebonite, while GB/T 1634.3 gives specific requirements for high-strength
thermosetting laminates.
This Part is suitable for assessing the relative behaviour of different types of
material at elevated temperature under load at a specified rate of temperature
increase. The results obtained do not necessarily represent maximum
applicable temperatures because in practice essential factors, such as time,
loading conditions and nominal surface stress, can differ from the test
conditions. True comparability of data can only be achieved for materials having
the same room-temperature flexural modulus.
This Part specifies preferred dimensions for the test specimens used. This Part
is commonly known as the HDT test (heat deflection test or heat distortion test),
although there is no official document using this designation.
2 Normative references
The following documents are indispensable for the application of this document.
For the dated references, only the editions with the dates indicated are
applicable to this document. For the undated references, the latest edition
(including all the amendments) are applicable to this document.
GB/T 1634.2 Plastics - Determination of temperature of deflection under load
- Part 2: Plastics and ebonite (GB/T 1634.2-2019, ISO 75-2:2013, MOD)
GB/T 1634.3 Plastics - Determination of temperature of deflection under load
- Part 3: High-strength thermosetting laminates (GB/T 1634.3-2004, ISO 75-
3:2003, IDT)
Force, applied to the test specimen at midspan, which results in a defined
flexural stress.
Note: It is expressed in newtons (N) [see 8.1, Formulae (1) to (3)].
3.7 Temperature of deflection under load; Tf
Temperature at which the deflection of the test specimen reaches the standard
deflection as the temperature is increased.
Note: It is expressed in degrees Celsius (°C).
4 Principle
A standard test specimen is subjected to three-point bending under a constant
load in the flatwise position to produce one of the flexural stresses given in the
relevant part of GB/T 1634. The temperature is raised at a uniform rate, and the
temperature at which the standard deflection, corresponding to the specified
increase in flexural strain, occurs is measured.
5 Apparatus
5.1 Means of producing a flexural stress
The apparatus shall be constructed essentially as shown in Figure 1. It consists
of a rigid metal frame in which a rod can move freely in the vertical direction.
The rod is fitted with a weight-carrying plate and a loading edge. The base of
the frame is fitted with test-specimen supports; these and the vertical members
of the frame are made of an alloy having the same coefficient of linear
expansion as the rod.
The test-specimen supports consist of two metal pieces that are cylindrical in
the contact area and with their lines of contact with the specimen in a horizontal
plane. The size of the span, i.e. of the distance between the contact lines, is
given in GB/T 1634.2 or GB/T 1634.3. The supports are fitted to the base of the
frame in such a way that the vertical force applied to the test specimen by the
loading edge is midway (±1 mm) between them. The contact edges of the
supports are parallel to the loading edge and at right angles to the length
direction of the test specimen placed symmetrically across them. The contact
edges of the supports and loading edge have a radius of (3.0 ± 0.2) mm and
shall be longer than the width of the test specimen.
Unless vertical parts of the apparatus have the same coefficient of linear
thermal expansion, the difference in change of length of these parts introduces
range of the instrument, it shall be measured in that part of the range in which
the instrument is to be used.
5.6 Micrometers and gauges
These are used to measure the width and thickness of the test specimens. They
shall be accurate to 0.01 mm.
6 Test specimens
6.1 General
All test specimens shall be free of warpage caused by thickness asymmetry.
Due to differences in the cooling conditions for moulded specimens or any
asymmetry in structure, for instance, the test specimens can warp during
heating, i.e. bend without a load. This shall be checked by loading the test
specimens on two opposite surfaces.
6.2 Shape and dimensions
Each test specimen shall be a bar of rectangular cross-section (length l > width
b > thickness h). The dimensions of the test specimens shall be as specified in
GB/T 1634.2 or GB/T 1634.3.
In each test specimen, the thickness and width over the central one third of the
length shall nowhere deviate by more than 2 % from the mean value.
Test specimens shall be produced as described in GB/T 1634.2 or GB/T 1634.3.
6.3 Specimen inspection
Specimens shall be free of twist and shall have mutually perpendicular adjacent
surfaces. All surfaces and edges shall be free from scratches, pits, sink marks
and flash.
Ensure that all cut surfaces are as smooth as possible, and that any
unavoidable machining marks are in the lengthwise direction.
The specimens shall be checked for conformity with these requirements by
visual observation against straight edges, squares and flat plates, and by
measuring with micrometer calipers.
Specimens showing measurable or observable departure from one or more of
these requirements shall be rejected or machined to proper size and shape
before testing.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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