ASTM D2538-95

Standard Practice for Fusion of Poly(Vinyl Chloride) (PVC) Compounds Using a Torque Rheometer

SCOPE
1.1 This practice covers the relative fusion characteristics of poly(vinyl chloride) compounds.
1.2 The test procedures appear in the following order: SectionFusion Test9 Thermal Stability Test10Color-Hold Stability Test11Shear Stability Test12
1.3 The values stated in SI units are to be regarded as the standard.
1.4  This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in Section 8 .
Note 1—There are no ISO standards covering the primary subject matter of this ASTM standard.

General Information

• Status: Historical
• Publication Date: 14-Jun-1995
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.15 - Thermoplastic Materials

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 2538 – 95 An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practice for
Fusion of Poly(Vinyl Chloride) (PVC) Compounds Using a
Torque Rheometer
This standard is issued under the fixed designation D 2538; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 5. Significance and Use
1.1 This practice covers the relative fusion characteristics of 5.1 When PVC compounds are mixed under appropriate
poly(vinyl chloride) compounds. conditions of heat and shear, a fused mass is produced. This
1.2 The test procedures appear in the following order: mass has certain melt characteristics which can be defined with
a torque rheometer operated under fixed conditions of shear
Section
and temperature. The fusion characteristics of a PVC com-
Fusion Test 9
pound are manifest as fusion time, fusion torque, melt torque,
Thermal Stability Test 10
Color-Hold Stability Test 11 melt viscosity, and heat and color stability.
Shear Stability Test 12
5.2 A control lot is to be used as a standard against which
other test results are to be compared. Test data are to be
1.3 The values stated in SI units are to be regarded as the
evaluated relative to the control lot.
standard.
1.4 This standard does not purport to address all of the
6. Apparatus
safety concerns, if any, associated with its use. It is the
6.1 Microprocessor Torque Rheometer, equipped with a
responsibility of the user of this standard to establish appro-
high-shear mixer with roller-style blades, bowl-jacket thermo-
priate safety and health practices and determine the applica-
couple, stock thermocouple, and temperature recorder.
bility of regulatory limitations prior to use. Specific hazards
statements are given in Section 8.
NOTE 2—A torque rheometer without microprocessor capability can be
used to perform the fusion, thermal stability, and color hold tests.
NOTE 1—There are no ISO standards covering the primary subject
matter of this ASTM standard.
6.1.1 For flexible and rigid compounds, use a Type 6 roller
head with a rotor ratio of 3 Drive:2 Driven.
2. Referenced Documents
NOTE 3—A Type 5 roller head can also be used, but the data generated
2.1 ASTM Standards:
cannot be compared with the Type 6 data.
D 883 Terminology Relating to Plastics
6.2 Quick-Loading Powder Chute or equivalent.
D 1600 Terminology for Abbreviated Terms Relating to
6.3 Brass Knife.
Plastics
6.4 Brass Wool or Brush.
3. Terminology
6.5 Insulated Gloves.
6.6 Balance, 500-g minimum capacity, with a 0.1-g sensi-
3.1 Definitions—Definitions are in accordance with Termi-
tivity.
nologies D 883 and D 1600 unless otherwise indicated.
6.7 Beaker, stainless steel, 400 mL.
4. Summary of Practice
6.8 Oven.
6.9 Aluminum Foil.
4.1 A sample of powder-mix compound is added to the
6.10 Timer.
heated roller mixer chamber and is transformed into a fused
6.11 Long-Nose Pliers.
mass.
6.12 Hand-Press Mold.
4.2 The resulting torque curve can be used to determine the
relative fusion time and fusion characteristics.
7. Materials
7.1 Poly(Vinyl Chloride) Resin.
This practice is under the jurisdiction of ASTM Committee D-20 on Plastics
7.2 Filter.
and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materi-
7.3 Lubricants.
als.
Current edition approved June 15, 1995. Published August 1995. Originally
published as D 2538 – 69. Last previous edition D 2538 – 94.
This edition contains changes in Section 9 and the addition of Appendix X2, in Suitable equipment may be obtained from C. W. Brabender, 50 E. Wesley St.,
order to transfer nonmandatory suggested conditions for operation to the appendix. South Hackensack, NJ 07606, and Haake Buchler Instruments, 244 Saddle River
Annual Book of ASTM Standards, Vol 08.01. Rd., Saddle Brook, NJ 07662.
D 2538
7.4 Plasticizer. 9.4 Interpretation of Torque Rheometer Curve (Fig. 1):
7.5 Process-Aid. 9.4.1 Fusion Torque—The point of maximum torque.
7.6 Impact Modifier. 9.4.2 Fusion Time—The time from the point of loading to
7.7 Stabilizer. the point of maximum torque.
7.8 Pigments. 9.4.3 Melt Torque—The fusion where the torque curve is
relatively flat.
8. Hazards
9.5 Report—Report the following information:
8.1 Do not exceed the power capacity of the instrument, as
9.5.1 The fusion torque to the nearest 100 m·g.
damage to the mixer or to the torque rheometer may result.
9.5.1.1 Report to the nearest 25 m·g when usinga0to 1000
8.2 Do not attempt to clean or poke objects into the mixer
scale.
while it is running.
9.5.2 The fusion time to the nearest ⁄2 min.
8.3 Gloves with sufficient insulation to enable the operator
9.5.3 The melt torque to the nearest 100 m·g.
to handle the hot equipment should be worn when conducting
9.5.3.1 Report to the nearest 25 m·g when usinga0to 1000
these tests.
scale.
9. Fusion Test Method
NOTE 6—If the melt torque is not steady, approximate the value and
9.1 Compound Preparation:
note whether the torque is increasing or decreasing.
9.1.1 The compound may be beaker-mixed, blended in an
9.5.4 Temperature of test, rotor revolutions per minute, and
intensive mixer or a ribbon blender, or blended and pelletized.
sample size used.
If the compound is beaker-mixed, the total weight of the
10. Thermal Stability Test Method
compound should equal the amount charged to the roller-head
bowl. 10.1 Prepare the test compound in accordance with 9.1.
9.2 Equipment Preparation:
10.2 Prepare the test equipment in accordance with 9.2.
9.2.1 Mount the roller head on the torque rheometer.
10.3 Procedure:
9.2.2 Select a temperature/rotor speed combination that will
10.3.1 Weigh a sample of the test compound in accordance
permit the test to be completed within a reasonable time
with 9.3.1. With the mixer running, position the quick-loading
constraint. Suggested combinations for several types of PVC
chute on the roller-head mixer and pour in the sample com-
compound are found in Appendix X2.
pound. Place the ram into the chute and add the weight. When
9.2.3 With the mixer empty and running, zero the recording
the torque curve indicates fusion, remove the loading chute and
pen on the chart.
weight.
9.3 Procedure:
9.3.1 Determine the sample size to be added to the mixer,
using the following formula:
sample size 5 @~V 2 D! 3 65 %# 3 specific gravity (1)
where:
V 5 volume of mixer bowl without rotors, and
D 5 volume displacement or rotors.
NOTE 4—The correct sample size for the mixer is when the fusion curve
will duplicate itself. As the mixer wears, it will be necessary to increase
the sample size to reproduce a fusion curve equivalent to previous curves.
9.3.2 Weigh a sample of the test compound in accordance
with 9.3.1. With the mixer running, position the quick-loading
chute on the roller-head mixer and pour in the sample com-
pound. Place the ram into the chute and add the weight. When
the torque curve indicates maximum torque has been reached,
remove the loading chute and weight.
9.3.3 Continue mixing until the melt torque achieves a
steady state.
9.3.4 Stop the mixer and open the bowl. Clean the com-
pound from the bowl and blades using the brass knife or wool,
or both.
9.3.5 Reassemble the mixing bowl and repeat 9.3.2-9.3.4
for additional tests. Since some cooling takes place when
cleaning the bowl, allow sufficient time to confirm that the
mixing bowl has reached equilibrium at the test temperature
before using again.
NOTE 5—The quick-loading chute should be at the same temperature at
the start of each test. Heat or cool as required. FIG. 1 Torque Rheometer Curve
D 2538
10.3.2 Continue running until there is a sudden rise in the 11.5.2 Usi
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