ASTM D5422-03
(Test Method)Standard Test Method for Measurement of Properties of Thermoplastic Materials by Screw-Extrusion Capillary Rheometer
Standard Test Method for Measurement of Properties of Thermoplastic Materials by Screw-Extrusion Capillary Rheometer
SIGNIFICANCE AND USE
This test method is useful for the characterization of thermoplastics and thermoplastic compounds, in terms of viscosity, or resistance to flow.
The data produced by this test method has been found useful in both quality-control testing and compound development. However, direct correlation with factory conditions is not implied.
Flow-performance data permits quality control of incoming thermoplastics and thermoplastic compounds because the flow parameters are sensitive to molecular weight and molecular-weight distribution. Therefore, this test method may distinguish differences between lots.
The shear viscosity or flow viscosity of thermoplastics and thermoplastic compounds will not only be sensitive to the raw-polymer molecular properties, but will also be affected by the type and amount of filler, additive, plasticizer, or stabilizer, by the type of copolymer blend, and by the addition of other compounding materials. This test method can serve as a quality-control tool for either incoming materials or for in-house quality-assurance checks on production mixing. This test method is useful to the research and development of new products in that the rheological behavior of a yet uncharacterized thermoplastic or thermoplastic compound can be measured and considered for comparative analysis.
SCOPE
1.1 This test method covers the use of a screw-extrusion-type capillary rheometer for the measurement of flow properties of thermoplastics and thermoplastic compounds. The measured flow properties, which are obtained through laboratory investigation, may help to describe the material behavior that occurs in factory processing.
1.2 Since a screw-type capillary rheometer imparts shear energy to the material during testing, the measurements will usually differ from those obtained with a piston-type capillary rheometer (see Test Method D3835).
1.3 Capillary rheometer measurements for thermoplastics and thermoplastic compounds are described in Test Method D3835.
1.4 The values stated in SI units are to be regarded as standard.
1.5 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.
Note 1--There is currently no equivalent ISO standard.
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Designation:D5422–03
Standard Test Method for
Measurement of Properties of Thermoplastic Materials by
1
Screw-Extrusion Capillary Rheometer
This standard is issued under the fixed designation D5422; 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.
INTRODUCTION
This test method uses capillary rheometry to measure the rheological properties of thermoplastics
and thermoplastic compounds. This test method utilizes a screw-extrusion-type capillary rheometer.
1. Scope* E691 Practice for Conducting an Interlaboratory Study to
4
Determine the Precision of a Test Method
1.1 This test method covers the use of a screw-extrusion-
type capillary rheometer for the measurement of flow proper-
3. Terminology
ties of thermoplastics and thermoplastic compounds. The
3.1 Definitions (See Terminology D 883) :
measured flow properties, which are obtained through labora-
3.1.1 apparent shear rate (g˙ )—shear strain rate (or veloc-
a
tory investigation, may help to describe the material behavior
ity gradient) of the thermoplastic or thermoplastic compound
that occurs in factory processing.
extrudate as it passes through the capillary die.
1.2 Since a screw-type capillary rheometer imparts shear
3.1.1.1 Discussion—This velocity gradient is not uniform
energy to the material during testing, the measurements will
through the cross-section of the capillary die. The shear rate is
usually differ from those obtained with a piston-type capillary
calculated for the region of highest shear, which is at the wall
rheometer (see Test Method D3835).
of the capillary. By selecting a die diameter and controlling the
1.3 Capillary rheometer measurements for thermoplastics
volume flow per unit time through the die, a specific level of
and thermoplastic compounds are described in Test Method
apparent shear rate may be achieved. Alternately, the shear
D3835.
stress (entrance pressure) may be controlled, and the apparent
1.4 The values stated in SI units are to be regarded as
shear rate measured.
standard.
3.1.1.2 Discussion—Mathematically, the apparent shear
1.5 This standard does not purport to address all of the
rate at the wall of the capillary for a Newtonian fluid at the
safety concerns, if any, associated with its use. It is the
capillary wall is given by the following:
responsibility of the user of this standard to establish appro-
32· Q
priate safety and health practices and determine the applica-
g˙ 5 (1)
a 3
bility of regulatory limitations prior to use.
p· D
NOTE 1—There is currently no equivalent ISO standard.
where:
−1
g˙ = apparent shear rate, s ,
a
2. Referenced Documents
3
Q = quantity of fluid extruded per time, mm /s,
2.1 ASTM Standards:
p = 3.142, and
2
D618 Practice for Conditioning Plastics for Testing
D = diameter of the measuring capillary, mm.
2
D883 Terminology Relating to Plastics
3.1.2 apparent shear stress (t )—themeasuredresistanceto
a
D1238 Test Method for Flow Rates of Thermoplastics by
the flow through a capillary die. It may be determined by
2
Extrusion Plastometer
measuring the die entrance pressure for a specific die, then
D3835 Test Method for Determination of Properties of
applying appropriate geometric factors.
3
Polymeric Materials by Means of a Capillary Rheometer
3.1.2.1 Discussion—Mathematically, apparent shear stress
is given by the following:
P
1
t 5 (2)
This test method is under the jurisdiction ofASTM Committee D20 on Plastics a
4· L/D!
~
and is the direct responsibility of Subcommittee D20.30 on Thermal Properties.
Current edition approved April 10, 2003. Published June 2003. Originally
approved in 1993. Last previous edition approved in 2000 as D5422–00.
2
Annual Book of ASTM Standards, Vol 08.01.
3 4
Annual Book of ASTM Standards, Vol 08.02. Annual Book of ASTM Standards, Vol 14.02.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D5422–03
using two or more dies of different length, but of the same
where:
diameter (and thus the same apparent shear rate, as calculated
t = apparent shear stress, Pa,
a
in3.1.4.2).Ifthedatafromtheseadditionaldiesarecompared,
P = pressure at the entrance of the measuring capillary,
Pa, either graphically or mathematically, a linear relationship of
L = length of the measuring capillary, mm, and extrusion pressure with die geometry is usually obtained in the
D = diameter of the measuring capillary, mm.
following form:
3.1.3 apparent viscosity (h )—ratio of apparent shear stress
a
L
P 5
...
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