ASTM D3364-99(2004)
(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
SIGNIFICANCE AND USE
This test method is useful for quality-control tests on PVC compounds having a wide range of melt viscosities. Measurements are made at shear rates close to 1 s−1.
In addition to the properties mentioned in Test Method D 1238, this technique is sensitive to plasticizer content, polymer molecular weight, polymer stability (both thermally and rheologically), shear instability, and general composition. The sensitivity of the material to temperature necessitates slightly tighter controls than those stated in Test Method D 1238.
The sensitivity of this test method makes it useful for correlating with processing conditions and as an aid in predicting changes in processing. However, as a one-point measure of flow relative to shear rate, its one drawback is that the same PVC melt flow values can be obtained for materials having different processibility; the chance of this happening is minimized, however, if the compounds are similar in composition.
Correlations with a wide range of processing conditions have supported the conclusions that little or no change in composition occurs during the test. Thus, this test is able to 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 polymers:
5.4.1 Thermal instability due to temperature effect.
5.4.2 Shear instability due to breaking of polymer bonds.
5.4.3 Rheological instability due to nonuniform distributions of widely different viscosity or molecular weight elements.
5.4.4 Thus, implications with respect to PVC molecular structural changes can be detected and predicted.
SCOPE
1.1 This test method is an extension of Test Method D 1238 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.
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.
There is no similar or equivalent ISO standard.
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Standards Content (Sample)
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Designation:D3364–99 (Reapproved 2004)
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 (´) indicates an editorial change since the last revision or reapproval.
NOTE 2—Since PVC obeys the power law function, the above relation-
1. Scope
ship can be expressed as follows:
1.1 This test method is an extension of Test Method D1238
1−N
(Viscosity) (Shear Rate) =(shear stress) in which the shear rate is
specific to the measurement of flow rates of poly(vinyl
expressed as 4Q/pR and depends on the power law exponent N.
chloride) (PVC) compounds while detecting and controlling
Since Qisthevolumetricflowrateintermsofcubicmillimetres/second
various polymer instabilities associated with the flow rate. and R is the radius of the die, it follows that the flow rate varies much
faster than the viscosity as a result of N.This means that the flow is much
1.2 This standard does not purport to address all of the
more sensitive to change than the viscosity. For PVC, N varies from 0.1
safety concerns, if any, associated with its use. It is the
to 0.33.
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
NOTE 1—There is no similar or equivalent ISO standard.
175°C.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 Conditions:
D883 Terminology Relating to Plastics
4.1.1 In order to test a wide variation of flow rates covering
D1238 Test Method for Melt Flow Rates of Thermoplastics
semirigid as well as nonrigid PVC compounds, the following
by Extrusion Plastometer
standard conditions are used:
D3835 Test Method for Determination of Properties of
Temperature 175°C [347°F]
Polymeric Materials by Means of a Capillary Rheometer
Total load on piston 20 000 g
E177 Practice for Use of the Terms Precision and Bias in
Approximate pressure 2758 kPa [400 psi]
Charge 2.15 6 0.05 g
ASTM Test Methods
Plugged orifice with 120° entrance angle
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method 4.2 Basis Principles:
4.2.1 Thelowertemperature(relativeto190°C)ischosento
3. Terminology
minimize thermal decomposition, maximize sensitivity of the
3.1 Definitions—For definitions related to plastics, see Ter- flow rate to structural changes in the PVC compound, and to
minology D883. allow a wide latitude of useful conditions associated with the
3.2 Definitions of Terms Specific to This Standard: load on the piston.
3.2.1 See Test Method D3835, Sections 5.1, 5.2, and 5.3. 4.2.2 Modern extrusion plastometers have been redesigned
3.2.2 Flow is the reciprocal of the viscosity; therefore, the to accommodate much higher loads. Current research for
flow is defined as the volumetric displacement through a multi-weight testing has reached levels of 50 kg and these are
controlled orifice and is expressed as shear rate over shear particularlygoodforrigidPVC.Previously,flowratesforrigid
stress. PVC were limited to 190°C. Recent research has shown that
rigid PVC can be run at 150°C and 50 kg loads.This weight is
effective for all semirigid PVC and even some nonrigid
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
and is the direct responsibility of Subcommittee D20.30 on Thermal Properties compounds. For flow rates in excess of 10 g/10 min (1000
(Section D20.30.08).
mg/min), lower weights are used, for example, color concen-
CurrenteditionapprovedNovember1,2004.PublishedJanuary2005.Originally
trates used in PVC extrusion may have flow rates in excess of
approved in 1974. Last previous edition approved in 1999 as D3364-99. DOI:
100g/10min(10 000mg/min)andwillrequirea5-kgloadon
10.1520/D3364-99R04.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
the piston.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3364–99 (2004)
NOTE—Specify material when ordering.
FIG. 1 Die Used for Test Method D3364
4.2.3 When the flow rates become very small as in the case extrusion, injection molding, milling, or mixing. These
of the stiffest semirigid containing 25 parts of plasticizer (flow changes are due to three types of measured instability in
rates below 15 mg/min), it may be desirable to use the die (flat polymers:
entry 8 mm [0.315 in.] long) in Test Method D1238. The flow 5.4.1 Thermal instability due to temperature effect.
is so slow that little rheological instability exists. By changing 5.4.2 Shear instability due to breaking of polymer bonds.
the die, approximately a tenfold increase in flow is achieved. 5.4.3 Rheological instability due to nonuniform distribu-
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
reduced by as much as 67% using a 9-g charge and 4.14 MPa
6. Apparatus
[600 psi] on the piston.
4.2.5 The plugged orifice should be used in all PVC 6.1 Plastometer—The apparatus is identical to that used in
compound work since the amount of charge is limited and Test Method D1238 except for the die. An alternative ther-
since the plugging for various times has been observed to give moregulator is suggested for improved temperature control.
significant variations in the flow rate. 6.2 Die:
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.
−1 to improve the L/D ratio.The dimensions of the regular die are
Measurements are made at shear rates close to 1 s .
shown in Fig. 1.
5.2 In addition to the properties mentioned in Test Method
6.3 Thermoregulator—Although a thermoregulator identi-
D1238, this technique is sensitive to plasticizer content,
cal to that used in Test Method D1238 may be used (provided
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.
5.4 Correlations with a wide range of processing conditions
have supported the conclusions that little or no change in
The “Thermo Watch” unit, manufactured by Instruments for Research and
composition occurs during the test. Thus, this test is able to
Industry, 103 FranklinAve., Cheltenham, PA19012, has been found satisfactory for
detect and follow profound changes which occur during this purpose.
D3364–99 (2004)
TABLE 1 Time Requirements for Cutting Specimens TABLE 2 Measurement Conversion to Milligrams per Minute
Flow Rate Factor for Obtaining Flow Rate
Time Interval Time Interval, min
Range, in mg/min Multiply By
Between Cuts Typical Type
mg/min
4 0.25
15 to 30 4 min semirigid 2 0.50
30 to 50 2 min semirigid 1 1.00
50 to 100 1 min semirigid 0.50 (30 s) 2.00
100 to 500 30 s nonrigid 0.25 (15 s) 4.00
400 to 1500 15 s nonrigid 0.167 (10 s) 6.00
1000 to 2000 10 s soft
Fluctuations up and down repeatedly during a run can indicate
7. Proce
...
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