GB/T 1633-2000 English PDF (GBT1633-2000)

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GB/T 1633-2000: Plastics - Thermoplastic materials - Determination of vicat softening temperature (VST)
GB/T 1633-2000
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.080.20
G 31
idt ISO 306:1994
Replacing GB/T 1633-1979 (1989)
Plastics - Thermoplastic materials - Determination of Vicat
softening temperature (VST)
ISSUED ON: JULY 31, 2000
IMPLEMENTED ON: MARCH 01, 2001
Issued by: State Bureau of Quality Technical Supervision
Table of Contents
Foreword ... 3
ISO Foreword ... 5
1 Scope ... 6
2 Normative references ... 6
3 Principle ... 7
4 Instruments ... 7
5 Specimens ... 9
6 State conditioning ... 10
7 Operating steps ... 10
8 Test report ... 11
Plastics - Thermoplastic materials - Determination of Vicat
softening temperature (VST)
1 Scope
This standard specifies four test methods for determining the Vicat softening
temperature (VST) of thermoplastics.
A50 method -- Using a force of 10 N, the heating rate is 50 °C/h
B50 method -- Using a force of 50 N, the heating rate is 50 °C/h
A120 method -- Using a force of 10 N, the heating rate is 120 °C/h
B120 method -- Using a force of 50 N, the heating rate is 120 °C/h
The four methods specified in this standard are only applicable to thermoplastics. The
temperature measured is the temperature at which thermoplastics begin to soften rapidly.
2 Normative references
The provisions contained in the following standards constitute the provisions of this
standard through reference in this standard. When this standard is published, the
versions shown are valid. All standards will be revised, and parties using this standard
shall explore the possibility of using the latest version of the following standards.
GB/T 2918-1998 Plastics - Standard atmospheres for conditioning and testing (idt
ISO 291:1997)
GB/T 9352-1988 Plastic - Compression moulding of test specimens of
thermoplastic materials (neq ISO 293:1986)
GB/T 11997-1989 Plastic - Multipurpose test specimens (eqv ISO 3167:1983)
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)
ISO 2818:1994 Plastics - Preparation of test specimens by machining
nickel-iron alloy or borosilicate glass), blank tests are performed for each instrument
including the temperature range in which it is used. A correction term is determined for
each temperature. If the correction term is 0.02 mm or greater, it shall note its algebraic
sign, which is added to the apparent penetration by algebraic methods. This correction
term is applied to each test. It is recommended to use instruments made of low
expansion alloys.
4.2 The indenter, preferably a cylinder made of hardened steel with a length of 3 mm
and a cross-sectional area of 1.000 mm2 ± 0.015 mm2. Fixed to the bottom of the load
rod, the lower surface of the indenter shall be flat, perpendicular to the axis of the load
rod, free of burrs.
4.3 A calibrated micrometer (or other suitable measuring instrument) capable of
measuring the penetration of the indenter into the specimen by 1 mm ± 0.01 mm and
recording the thrust of the micrometer as part of the thrust of the specimen.
Note:
1. In this type of instrument, the micrometer spring force is upward and shall be subtracted
from the load; if this force is downward, it shall be added to the load.
2. During the entire stroke, since the force applied to the micrometer spring changes
significantly, this force shall be measured throughout the stroke.
4.4 Load plate is mounted on the load rod, which has a suitable weight in the center, so
that the total thrust applied to the specimen reaches 10 N ± 0.2 N for A50 and A120, or
50 N ± 1 N for B50 and B120. The downward thrust of the load rod, indenter, load plate
micrometer spring combination shall not exceed 1 N.
4.5 Heating equipment uses a heating bath, which is filled with liquid, OR a forced blast
nitrogen circulation oven. The heating equipment shall be equipped with a controller,
that can heat up at a uniform rate of 50 °C/h ± 5 °C/h or 120 °C/h ± 10 °C/h as required.
During the test, if the temperature change every 6 minutes is 5 °C ± 0.5 °C or 12 °C ±
1 °C, respectively, the heating rate shall be considered to meet the requirements.
Adjust the instrument so that when the specified indentation is reached, the heater is
automatically cut off and an alarm sounds.
4.5.1 Heating bath contains the liquid in which the specimen is immersed and is
equipped with an efficient stirrer; the specimen is immersed to a depth of at least 35
mm. Make sure that the selected liquid is stable at the use temperature and has no effect
on the test material, such as expansion or cracking.
When a heating bath is used, the temperature of the liquid near the specimen is
measured as the Vicat softening temperature (VST) (see 7.5).
Liquid paraffin, transformer oil, glycerine, silicone oil are all suitable heat transfer
5.3 For sheet materials, the specimen thickness shall be equal to the original sheet
thickness, except as follows:
a) If the specimen thickness exceeds 6.5 mm, it shall be reduced to 3 ~ 6.5 mm by
mechanical processing on one side in accordance with ISO 2818, leaving the other
surface intact. The test surface shall be the original surface.
b) If the sheet thickness is less than 3 mm, up to three specimens shall be directly
superimposed together, so that the total thickness is between 3 ~ 6.5 mm, with the
thickness of the upper sheet being at least 1.5 mm. Superimposing sheets of
smaller thickness may not necessarily give the same test results.
5.4 The test results obtained may be related to the molding conditions used to prepare
the specimens, although such dependence is uncommon. When the test results depend
on the molding conditions, special annealing or pretreatment steps may be used before
testing after agreement between the parties concerned.
6 State conditioning
Unless there are provisions or requirements for the materials under test, the specimen
shall be conditioned according to GB/T 2918.
7 Operating steps
7.1 Place the specimen horizontally under the unloaded indenter. The indenter shall be
no less than 3 mm from the edge of the specimen; the specimen surface in contact with
the instrument base shall be flat.
7.2 Place the assembly in the heating device and start the agitator. At the beginning of
each test, the temperature of the heating device shall be 20 ~ 23 °C. When using a
heating bath, the mercury ball of the thermometer or the sensing part of the temperature
measuring instrument shall be at the same level as the specimen and as close to the
specimen as possible. If the preliminary test shows that starting the test at other
temperatures will not cause errors for the test material, other starting temperatures can
be used.
7.3 After 5 min, with the indenter in a stationary position, add sufficient weight to the
load plate, so that the total thrust on the specimen is 10 N ± 0.2 N for A50 and A120 and
50 N ± 1 N for B50 and B120. Then, take the reading of the dial gauge (or other
indentation measuring instrument) or zero the instrument.
7.4 Raise the temperature of the heating device at a rate of 50 °C/h ± 5 °C/h or 120 °C/h
± 10 °C/h; when using a heating bath, stir the liquid thoroughly during the test; for
arbitration tests, use a heating rate of 50 °C/h.