ASTM D3364-99
(Test Method)Standard Test Method for Flow Rates for Poly(Vinyl Chloride) with Molecular Structural Implications
Standard Test Method for Flow Rates for Poly(Vinyl Chloride) with Molecular Structural Implications
SCOPE
1.1 This test method is an extension of Test Method D1238 specific to the measurement of flow rates of poly(vinyl chloride) (PVC) compounds while detecting and controlling various polymer instabilities associated with the flow rate.
1.2 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 no similar or equivalent ISO standard.
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Designation:D3364–99
Standard Test Method for
Flow Rates for Poly(Vinyl Chloride) with Molecular
Structural Implications
This standard is issued under the fixed designation D3364; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
ship can be expressed as follows:
1. Scope
1−N
(Viscosity) (Shear Rate) =(shear stress) in which the shear rate is
1.1 This test method is an extension ofTest Method D1238
expressed as 4Q/pR and depends on the power law exponent N.
specific to the measurement of flow rates of poly(vinyl
Since Qisthevolumetricflowrateintermsofcubicmillimetres/second
chloride) (PVC) compounds while detecting and controlling
and R is the radius of the die, it follows that the flow rate varies much
various polymer instabilities associated with the flow rate. faster than the viscosity as a result of N.This means that the flow is much
more sensitive to change than the viscosity. For PVC, N varies from 0.1
1.2 This standard does not purport to address all of the
to 0.33.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.2.3 Flow rate by this test method is the rate in milligrams/
priate safety and health practices and determine the applica- minute at which polymer flows through a specific die (see Fig.
bility of regulatory limitations prior to use.
1) with a total load on the ram of 20 kg at a temperature of
175°C.
NOTE 1—There is no similar or equivalent ISO standard.
4. Summary of Test Method
2. Referenced Documents
4.1 Conditions:
2.1 ASTM Standards:
2 4.1.1 In order to test a wide variation of flow rates covering
D883 Terminology Relating to Plastics
semirigid as well as nonrigid PVC compounds, the following
D1238 Test Method for Flow Rates of Thermoplastics by
2 standard conditions are used:
Extrusion Plastometer
Temperature 175°C (347°F)
D3835 Test Method for Rheological Properties ofThermo-
Total load on piston 20 000 g
plastics with a Capillary Rheometer
Approximate pressure 2758 kPa (400 psi)
E177 Practice for Use of the Terms Precision and Bias in Charge 2.15 6 0.05 g
4 Plugged orifice with 120° entrance angle
ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to
4.2 Basis Principles:
Determine the Precision of a Test Method
4.2.1 Thelowertemperature(relativeto190°C)ischosento
minimize thermal decomposition, maximize sensitivity of the
3. Terminology
flow rate to structural changes in the PVC compound, and to
3.1 Definitions—For definitions related to plastics, see Ter-
allow a wide latitude of useful conditions associated with the
minology D883.
load on the piston.
3.2 Definitions of Terms Specific to This Standard:
4.2.2 Modern extrusion plastometers have been redesigned
3.2.1 See Test Method D3835, Sections 5.1, 5.2, and 5.3.
to accomodate much higher loads. Current research for multi-
3.2.2 Flow is the reciprocal of the viscosity; therefore, the
weight testing has reached levels of 50 kg and these are
flow is defined as the volumetric displacement through a
particularlygoodforrigidPVC.Previously,flowratesforrigid
controlled orifice and is expressed as shear rate over shear
PVC were limited to 190°C. Recent research has shown that
stress.
rigid PVC can be run at 150°C and 50 kg loads.This weight is
effective for all semirigid PVC and even some nonrigid
NOTE 2—Since PVC obeys the power law function, the above relation-
compounds. For flow rates in excess of 10 g/10 min (1000
mg/min), lower weights are used, for example, color concen-
ThistestmethodisunderthejurisdictionofASTMCommitteeD-20onPlastics
trates used in PVC extrusion may have flow rates in excess of
and is the direct responsibility of Subcommittee D20.30 on Thermal Properties
100g/10min(10 000mg/min)andwillrequirea5-kgloadon
(Section D20.30.08).
the piston.
Current edition approved March 10, 1999. Published June 1999. Originally
published as D3364–74. Last previous edition D3364–94.
4.2.3 When the flow rates become very small as in the case
Annual Book of ASTM Standards, Vol 08.01.
of the stiffest semirigid containing 25 parts of plasticizer (flow
Annual Book of ASTM Standards, Vol 08.02.
4 rates below 15 mg/min), it may be desirable to use the die (flat
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3364
NOTE—Specify material when ordering.
FIG. 1 Die Used for Test Method D3364
entry 8 mm (0.315 in.) long) inTest Method D1238.The flow 5.4.2 Shear instability due to breaking of polymer bonds.
is so slow that little rheological instability exists. By changing 5.4.3 Rheological instability due to nonuniform distribu-
the die, approximately a tenfold increase in flow is achieved. tions of widely different viscosity or molecular weight ele-
4.2.4 The charge size is important. Many PVC compounds ments.
are elastic in nature, causing a severe loss in pressure from the 5.4.4 Thus, implications with respect to PVC molecular
bottom of the piston through the material to the orifice of the structural changes can be detected and predicted.
die. Evidence indicates that the force to extrude may be
6. Apparatus
reduced by as much as 67% using a 9-g charge and 4.14 MPa
(600 psi) on the piston.
6.1 Plastometer—The apparatus is identical to that used in
4.2.5 The plugged orifice should be used in all PVC
Test Method D1238 except for the die. An alternative ther-
compound work since the amount of charge is limited and
moregulator is suggested for improved temperature control.
since the plugging for various times has been observed to give
6.2 Die:
significant variations in the flow rate.
6.2.1 Thedieisapproximatelythreetimesaslongastheone
used in Test Method D1238, a major factor in controlling any
5. Significance and Use
rheological instability in the polymer. If instability still occurs,
5.1 This test method is useful for quality-control tests on particularly at high flow rates, dies 2 in. or longer can be used
PVC compounds having a wide range of melt viscosities. to improve the L/D ratio.The dimensions of the regular die are
−1
shown in Fig. 1.
Measurements are made at shear rates close to 1 s .
5.2 In addition to the properties mentioned in Test Method 6.3 Thermoregulator—Although a thermoregulator identi-
cal to that used in Test Method D1238 may be used (provided
D1238, this technique is sensitive to plasticizer content,
polymer molecular weight, polymer stability (both thermally it regulates to 175 6 0.1°C), a unit coupled with a 90° angle
and rheologically), shear instability, and general composition. thermometer, divided into 0.1°C is suggested for improved
The sensitivity of the material to temperature necessitates reproducibility. Most regulators designed for Test Method
slightly tighter controls than those stated in Test Method D1238 cannot control better than 60.2°C. The sensitivity of
D1238. this test method is illustrated by the fact that a 19% change in
5.3 The sensitivity of this test method makes it useful for flow rate is observed on a typical PVC compound with a 1°C
correlating with processing conditions and as an aid in predict- change in temperatures.
ingchangesinprocessing.However,asaone-pointmeasureof 6.4 Thermometer, measuring the standard temperature,
flow relative to shear rate, its one drawback is that the same should rest on the top of the orifice to conform with conditions
PVC melt flow values can be obtained for materials having in accordance with Test Method D1238 ( ⁄2 in. above the
different processibility; the chance of this happening is mini- shorter orifice).
mized, however, if the compounds are similar in composition.
7. Procedure
5.4 Correlations with a wide range of processing conditions
have supported the conclusions that little or no change in
7.1 Check that the temperature is controlled to 60.1°C in
composition occurs during the test. Thus, this test is able to
the range from 174.9 to 175.1°C.
detect and follow profound changes which occur during
extrusion, injection molding, milling, or mixing. These
changes are due to three types of measured instability in
The “Thermo Watch” unit, manufactured by Instruments for Research and
polymers:
Industry, 103 FranklinAve., Cheltenham, PA19012, has been found satisfactory for
5.4.1 Thermal instability due to temperature effect. this purpose.
D3364
7.2 The apparatus must be clean. 7.14 Determine the diameter of the extrudate for the first
7.3 Withthedieinplace,plugtheorifice(asharpenedwood and fifth stable specimens with a micrometer. If the difference
dowel is a satisfactory plug). between the two specimens is greater than 0.15 mm (0.006 in.)
7.4 Allow the die and plug to heat at least 3 min. (the normal PVC swell, observed for a wide range of PVC
compounds), report the total difference as PVC swelling
7.5 Start the stopwatch and charge 2.15 6 0.05 g of the
PVC compound
...
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