1、Designation: D 3364 99 (Reapproved 2004)Standard Test Method forFlow Rates for Poly(Vinyl Chloride) with MolecularStructural Implications1This standard is issued under the fixed designation D 3364; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is an extension of Test Method D 1238specific to the measurement of flow
3、rates of poly(vinylchloride) (PVC) compounds while detecting and controllingvarious polymer instabilities associated with the flow rate.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to es
4、tablish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1238 Test Method for Flow Rates of Thermopl
5、astics byExtrusion PlastometerD 3835 Test Method for Rheological Properties of Thermo-plastics with a Capillary RheometerE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Termi
6、nology3.1 DefinitionsFor definitions related to plastics, see Ter-minology D 883.3.2 Definitions of Terms Specific to This Standard:3.2.1 See Test Method D 3835, Sections 5.1, 5.2, and 5.3.3.2.2 Flow is the reciprocal of the viscosity; therefore, theflow is defined as the volumetric displacement thr
7、ough acontrolled orifice and is expressed as shear rate over shearstress.NOTE 2Since PVC obeys the power law function, the above relation-ship can be expressed as follows:(Viscosity) (Shear Rate)1N= (shear stress) in which the shear rate isexpressed as 4Q/pR3and depends on the power law exponent N.S
8、ince Q is the volumetric flow rate in terms of cubic millimetres/secondand R is the radius of the die, it follows that the flow rate varies muchfaster than the viscosity as a result of N. This means that the flow is muchmore sensitive to change than the viscosity. For PVC, N varies from 0.1to 0.33.3
9、.2.3 Flow rate by this test method is the rate in milligrams/minute at which polymer flows through a specific die (see Fig.1) with a total load on the ram of 20 kg at a temperature of175C.4. Summary of Test Method4.1 Conditions:4.1.1 In order to test a wide variation of flow rates coveringsemirigid
10、as well as nonrigid PVC compounds, the followingstandard conditions are used:Temperature 175C 347FTotal load on piston 20 000 gApproximate pressure 2758 kPa 400 psiCharge 2.15 6 0.05 gPlugged orifice with 120 entrance angle4.2 Basis Principles:4.2.1 The lower temperature (relative to 190C) is chosen
11、 tominimize thermal decomposition, maximize sensitivity of theflow rate to structural changes in the PVC compound, and toallow a wide latitude of useful conditions associated with theload on the piston.4.2.2 Modern extrusion plastometers have been redesignedto accommodate much higher loads. Current
12、research formulti-weight testing has reached levels of 50 kg and these areparticularly good for rigid PVC. Previously, flow rates for rigidPVC were limited to 190C. Recent research has shown thatrigid PVC can be run at 150C and 50 kg loads. This weight iseffective for all semirigid PVC and even some
13、 nonrigidcompounds. For flow rates in excess of 10 g/10 min (1000mg/min), lower weights are used, for example, color concen-trates used in PVC extrusion may have flow rates in excess of100 g/10 min (10 000 mg/min) and will require a 5-kg load onthe piston.1This test method is under the jurisdiction
14、ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 on Thermal Properties(Section D20.30.08).Current edition approved November 1, 2004. Published January 2005. Originallyapproved in 1974. Last previous edition approved in 1999 as D 3364 - 99.2For referenced ASTM s
15、tandards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocke
16、n, PA 19428-2959, United States.4.2.3 When the flow rates become very small as in the caseof the stiffest semirigid containing 25 parts of plasticizer (flowrates below 15 mg/min), it may be desirable to use the die (flatentry 8 mm 0.315 in. long) in Test Method D 1238. The flowis so slow that little
17、 rheological instability exists. By changingthe die, approximately a tenfold increase in flow is achieved.4.2.4 The charge size is important. Many PVC compoundsare elastic in nature, causing a severe loss in pressure from thebottom of the piston through the material to the orifice of thedie. Evidenc
18、e indicates that the force to extrude may bereduced by as much as 67 % using a 9-g charge and 4.14 MPa600 psi on the piston.4.2.5 The plugged orifice should be used in all PVCcompound work since the amount of charge is limited andsince the plugging for various times has been observed to givesignific
19、ant variations in the flow rate.5. Significance and Use5.1 This test method is useful for quality-control tests onPVC compounds having a wide range of melt viscosities.Measurements are made at shear rates close to 1 s1.5.2 In addition to the properties mentioned in Test MethodD 1238, this technique
20、is sensitive to plasticizer content,polymer molecular weight, polymer stability (both thermallyand rheologically), shear instability, and general composition.The sensitivity of the material to temperature necessitatesslightly tighter controls than those stated in Test MethodD 1238.5.3 The sensitivit
21、y of this test method makes it useful forcorrelating with processing conditions and as an aid in predict-ing changes in processing. However, as a one-point measure offlow relative to shear rate, its one drawback is that the samePVC melt flow values can be obtained for materials havingdifferent proce
22、ssibility; the chance of this happening is mini-mized, however, if the compounds are similar in composition.5.4 Correlations with a wide range of processing conditionshave supported the conclusions that little or no change incomposition occurs during the test. Thus, this test is able todetect and fo
23、llow profound changes which occur duringextrusion, injection molding, milling, or mixing. Thesechanges are due to three types of measured instability inpolymers: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
24、due to nonuniform distribu-tions of widely different viscosity or molecular weight ele-ments.5.4.4 Thus, implications with respect to PVC molecularstructural changes can be detected and predicted.6. Apparatus6.1 PlastometerThe apparatus is identical to that used inTest Method D 1238 except for the d
25、ie. An alternative ther-moregulator is suggested for improved temperature control.6.2 Die:6.2.1 The die is approximately three times as long as the oneused in Test Method D 1238, a major factor in controlling anyrheological instability in the polymer. If instability still occurs,particularly at high
26、 flow rates, dies 2 in. or longer can be usedto improve the L/D ratio. The dimensions of the regular die areshown in Fig. 1.6.3 ThermoregulatorAlthough a thermoregulator identi-cal to that used in Test Method D 1238 may be used (providedit regulates to 175 6 0.1C), a unit3coupled with a 90 anglether
27、mometer, divided into 0.1C is suggested for improvedreproducibility. Most regulators designed for Test MethodD 1238 cannot control better than 60.2C. The sensitivity ofthis test method is illustrated by the fact that a 19 % change inflow rate is observed on a typical PVC compound with a 1Cchange in
28、temperatures.6.4 Thermometer, measuring the standard temperature,should rest on the top of the orifice to conform with conditionsin accordance with Test Method D 1238 (12 in. above theshorter orifice).3The “Thermo Watch” unit, manufactured by Instruments for Research andIndustry, 103 Franklin Ave.,
29、Cheltenham, PA 19012, has been found satisfactory forthis purpose.NOTESpecify material when ordering.FIG. 1 Die Used for Test Method D 3364D 3364 99 (2004)27. Procedure7.1 Check that the temperature is controlled to 60.1C inthe range from 174.9 to 175.1C.7.2 The apparatus must be clean.7.3 With the
30、die in place, plug the orifice (a sharpened wooddowel is a satisfactory plug).7.4 Allow the die and plug to heat at least 3 min.7.5 Start the stopwatch and charge 2.15 6 0.05 g of thePVC compound into the bore. When charging is complete,pack down the PVC with the phenolic-coated charging tool byrepe
31、ated thrusts.7.6 Place the piston in the bore and add sufficient weights tomake the total mass including the piston equal to 20 kg 6 10g. The entire time of charging and positioning of weightsshould take no longer than 1 min and preferably less than12min. If charging time is greater than 1 min, clea
32、n out theinstrument and repeat the procedure.7.7 When the stopwatch reads exactly 360 s (6 min), pull theplug from the orifice.7.8 At this time (6 min) and without stopping the stopwatch,cut off the extruded portion very cleanly with the spatulaexactly when the second hand of the watch reaches zero.
33、 Passthe tip of the spatula upward along one side of the beveledhole, lightly across the bottom of the orifice, and downwardalong the opposite side. Make the cut quickly and neatly forbest precision.Aclean sharp cut is desirable so that succeedingportions will extrude straight, not curled. It may be
34、 necessaryto reshape the end of the cutoff tool to obtain the best results.7.9 The time for cutting the specimen shall be in accordancewith Table 1. As a guide, each specimen should be about 20 to30 mm long.7.10 Place the cut specimen in the slotted tray in the ordertaken.7.11 Continue to take speci
35、mens up to and including 42 minor until flow stops, whichever is sooner.7.12 Weigh and record the results to the closest 1 mg.Average the five successive most stable values near the end ofthe run and express as milligrams per minute. This averagevalue is the PVC flow rate. Do not use the first two o
36、r last twovalues since these are normally unstable values.NOTE 3Occasionally, the values change throughout the run. This maybe due to variable lubricant conditions at the metal surfaces or chemicalchanges in the PVC compound. Under these conditions, average thevalues after discarding the first three
37、 values and the last two. The cause ofthis unstable condition should be studied and understood.7.13 Of the five stable specimens, subtract the weight of thefifth from that of the first. Divide the difference by the averageand multiply by 100. Report as percent PVC instability.Fluctuations up and dow
38、n repeatedly during a run can indicatenonuniform mixing or a bad charging technique.7.14 Determine the diameter of the extrudate for the firstand fifth stable specimens with a micrometer. If the differencebetween the two specimens is greater than 0.15 mm 0.006 in.(the normal PVC swell, observed for
39、a wide range of PVCcompounds), report the total difference as PVC swellinginstability. Be careful not to squeeze the specimen; the speci-men should fit the micrometer setting easily, but not quite fallfree.7.15 Remove the weights and piston, and clean the pistonwith a cloth.7.16 Push the die out of
40、the top of the cylinder with thepush-out tool. Push out any molten PVC in the orifice with theorifice broach. Put the die (hot) into methyl ethyl ketone inorder to break the PVC skin away from the orifice. Dry off thecooled die with a cloth and inspect to see that the orifice isclean. At least twice
41、 a day check the orifice with the “go-no-go” gage.7.17 Clean up the cylinder, replace the die, and insert theplug. The instrument is now ready for the next test. Return to7.4.8. Calculation8.1 The simple average of the five values is first posted asthe milligrams per time scale. The PVC melt flow va
42、lue is thenobtained by adjusting the value to milligrams per minute (seeTable 2).8.2 The instability is measured by subtracting the weight ofthe fifth or last specimen from the first specimen. The value forthe instability will then be positive or negative. Thus,200 mg/15 s 4th specimen250 mg/15 s 9t
43、h specimen8.3 Calculate the simple average and the instability value asfollows:instability 5250 mg/15 s (1)average 5 225 mg/15 s2502255222.2 %where:instability =FR42 FR9average FR3 100 ,FR4= flow rate of 4th specimen, andFR9= flow rate of 9th specimen.NOTE 4A positive instability probably indicates
44、that crosslinking isoccurring. A negative instability indicates either a degradation of theTABLE 1 Time Requirements for Cutting SpecimensFlow RateRange,mg/minTime IntervalBetween Cuts Typical Type15 to 30 4 min semirigid30 to 50 2 min semirigid50 to 100 1 min semirigid100 to 500 30 s nonrigid400 to
45、 1500 15 s nonrigid1000 to 2000 10 s softTABLE 2 Measurement Conversion to Milligrams per MinuteTime Interval, minFactor for Obtaining Flow Ratein mg/min Multiply By4 0.252 0.501 1.000.50 (30 s) 2.000.25 (15 s) 4.000.167 (10 s) 6.00D 3364 99 (2004)3polymer or a change in the lubricant function at th
46、e metal surface of thedie.9. Report9.1 Report the following information:9.1.1 PVC flow rate, stating the date, any process informa-tion, sample identification, weight on the piston, and die,9.1.2 Percent PVC instability,9.1.3 PVC swelling instability, and9.1.4 Any change in color, referenced to the
47、time at whichit occurred.10. Precision and Bias10.1 Precision:10.1.1 Table 3 is based on a round robin4conducted in 1991in accordance with Practice E 691, involving three materialstested by seven laboratories. For each material, all the sampleswere prepared at one source, but the individual specimen
48、s wereprepared at the laboratories which tested them. Each test resultwas the average of five individual determinations. Each labo-ratory obtained three test results for each material.(WarningThe following explanations of r and R (10.1.2-10.1.2.3) are intended only to present a meaningful way ofcons
49、idering the approximate precision of this test method. Thedata in Table 3 should not be rigorously applied to acceptanceor rejection of material, as those data are specific to the roundrobin and may not be representative of other lots, conditions,materials, or laboratories. Users of this test method shouldapply the principles outlined in Practice E 691 to generate dataspecific to their laboratory and materials, or between specificlaboratories. The principles of 10.1.2-10.1.2.3 would then bevalid for such data.)10.1.2 Concept of r and RIf Srand SR
