ASTM D3364-1999(2011) Standard Test Method for Flow Rates for Poly(Vinyl Chloride) with Molecular Structural Implications《测定受分子结构影响的聚乙烯(氯乙烯)流率的标准试验方法》.pdf

《ASTM D3364-1999(2011) Standard Test Method for Flow Rates for Poly(Vinyl Chloride) with Molecular Structural Implications《测定受分子结构影响的聚乙烯(氯乙烯)流率的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM D3364-1999(2011) Standard Test Method for Flow Rates for Poly(Vinyl Chloride) with Molecular Structural Implications《测定受分子结构影响的聚乙烯(氯乙烯)流率的标准试验方法》.pdf（4页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D3364 99 (Reapproved 2011)Standard Test Method forFlow Rates for Poly(Vinyl Chloride) with MolecularStructural Implications1This standard is issued under the fixed designation D3364; the number immediately following the designation indicates the year oforiginal adoption or, in the case

2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is an extension of Test Method D1238specific to the measurement of flow rate

3、s of poly(vinylchloride) (PVC) compounds while detecting and controllingvarious polymer instabilities associated with the flow rate.1.2 The values stated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for i

4、nforma-tion only and are not considered standard.1.3 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 establish appro-priate safety and health practices and determine the applica-bility of re

5、gulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1238 Test Method for Melt Flow Rates of Thermoplasticsby Extrusion PlastometerD3835 Test Method for Determination of Properties o

6、fPolymeric Materials by Means of a Capillary RheometerE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsFor definitions related to plastics, see Ter-min

7、ology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 See Test Method D3835, 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 through acontrolled orifice and is expressed as shear rate over shearstres

8、s.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.Since Q is the volumetric flow rate in terms of cubic millimetres/second

9、and 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 0.33.3.2.3 Flow rate by this test method is the rate in milligrams/minute at

10、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 as well as nonrigid PVC compounds, the followingstandard conditions are

11、 used:Temperature 175C (347F)Total load on piston 20 000 gApproximate pressure 2758 kPa (400 psi)Charge 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 tominimize thermal decomposition, maximize sensitivity of theflow

12、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 research formulti-weight testing has reached levels of 50 kg and th

13、ese 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 nonrigid1This test method is under the jurisdiction ofASTM Committ

14、ee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 on Thermal Properties.Current edition approved Sept. 1, 2011. Published October 2011. Originallyapproved in 1974. Last previous edition approved in 2004 as D3364 - 99 (2004).DOI: 10.1520/D3364-99R11.2For referenced ASTM standa

15、rds, 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 Conshohocken, PA

16、 19428-2959, United Spounds. 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.4.2.3 When the flow rates become ve

17、ry 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 D1238. The flowis so slow that little rheological instability exists. By changingthe die, approximately

18、 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. Evidence indicates that the force to extrude may bereduced by as much as

19、67 % using a 9-g charge and 4.14 MPa(600 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 givesignificant variations in the flow rate.5. Significance and Use5.1 This

20、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 MethodD1238, this technique is sensitive to plasticizer content,polymer molecular weight, pol

21、ymer stability (both thermallyand rheologically), shear instability, and general composition.The sensitivity of the material to temperature necessitatesslightly tighter controls than those stated in Test MethodD1238.5.3 The sensitivity of this test method makes it useful forcorrelating with processi

22、ng 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 processibility; the chance of this happening is mini-mized, however, if

23、 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 follow profound changes which occur duringextrusion, injection moldi

24、ng, 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 due to nonuniform distribu-tions of widely different viscosity or

25、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 D1238 except for the die. An alternative thermo-regulator is suggested for improved tempe

26、rature control.6.2 Die:6.2.1 The die is approximately three times as long as the oneused in Test Method D1238, a major factor in controlling anyrheological instability in the polymer. If instability still occurs,particularly at high flow rates, dies 2 in. or longer can be usedto improve the L/D rati

27、o. The dimensions of the regular die areshown in Fig. 1.6.3 ThermoregulatorAlthough a thermoregulator identi-cal to that used in Test Method D1238 may be used (providedit regulates to 175 6 0.1C), a unit3coupled with a 90 anglethermometer, divided into 0.1C is suggested for improvedreproducibility.

28、Most regulators designed for Test MethodD1238 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 temperatures.3The “Thermo Watch” unit, manufactured by Instruments for

29、 Research andIndustry, 103 FranklinAve., Cheltenham, PA19012, has been found satisfactory forthis purpose.NOTESpecify material when ordering.FIG. 1 Die Used for Test Method D3364D3364 99 (2011)26.4 Thermometer, measuring the standard temperature,should rest on the top of the orifice to conform with

30、conditionsin accordance with Test Method D1238 (12 in. above theshorter orifice).7. 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 die in place, plug the orifice (a sharpened wooddowel is a satisfactory plu

31、g).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 byrepeated thrusts.7.6 Place the piston in the bore and add sufficient weights to

32、make 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, clean out theinstrument and repeat the procedure.7.7 When the stopwatch reads e

33、xactly 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. Passthe tip of the spatula upward along one side of the beveledhole, light

34、ly 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 necessaryto reshape the end of the cutoff tool to obtain the best results.

35、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 specimens up to and including 42 minor until flow stops, whichever is sooner.7.1

36、2 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 or last twovalues since these are normally unstable values.NOTE 3Occasionall

37、y, 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 values and the last two. The cause ofthis unstable condition should be stu

38、died 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 down repeatedly during a run can indicatenonuniform mixing or a bad charging t

39、echnique.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 a wide range of PVCcompounds), report the total difference as PVC swellin

40、ginstability. 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 the top of the cylinder with thepush-out tool. Push out any molten PVC in

41、 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 a day check the orifice with the “go-no-go” gage.7.17 Clean up the cylin

42、der, 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 value is thenobtained by adjusting the value to milligrams per minute (seeT

43、able 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 9th specimen8.3 Calculate the simple average and the instability value asfo

44、llows:instability 5250 mg/15 s (1)average 5 225 mg/15 s2502255222.2 %where:instability =FR42 FR9average FR3 100 ,TABLE 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 5

45、00 30 s nonrigid400 to 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) 6.00D3364 99 (2011)3FR4= flow rate of 4th specimen

46、, andFR9= flow rate of 9th specimen.NOTE 4A positive instability probably indicates that crosslinking isoccurring. A negative instability indicates either a degradation of thepolymer or a change in the lubricant function at the metal surface of thedie.9. Report9.1 Report the following information:9.

47、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 time at whichit occurred.10. Precision and Bias10.1 Precision:10.1.1 Table

48、 3 is based on a round robin4conducted in 1991in accordance with Practice E691, involving three materialstested by seven laboratories. For each material, all the sampleswere prepared at one source, but the individual specimens wereprepared at the laboratories which tested them. Each test resultwas t

49、he 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 ofconsidering 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