1、Designation: D2538 02 (Reapproved 2010)D2538 18Standard Practice forFusion of Poly(Vinyl Chloride) (PVC) Compounds Using aTorque Rheometer1This standard is issued under the fixed designation D2538; 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the relative fusion characteristics of poly(vinyl chloride) compounds.
3、1.2 The test procedures appear in the following order:SectionFusion Test 9Thermal Stability Test 10Color-Hold Stability Test 11Shear Stability Test 121.3 The values stated in SI units are to be regarded as the standard.1.4 This standard does not purport to address all of the safety concerns, if any,
4、 associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use. Specific hazards statements are given in Section 8.NOTE 1There are n
5、o ISO standards covering the primary subject matter of this ASTM standard.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Reco
6、mmendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1600 Terminology for Abbreviated Terms Relating to PlasticsE691 Practice for Conducting an Interlaboratory Study to Determine
7、 the Precision of a Test Method3. Terminology3.1 DefinitionsDefinitions are in accordance with Terminologies D883 and D1600 unless otherwise indicated.4. Summary of Practice4.1 A sample of powder-mix compound is added to the heated roller mixer chamber and is transformed into a fused mass.4.2 The re
8、sulting torque curve can be used to determine the relative fusion time and fusion characteristics.5. Significance and Use5.1 When PVC compounds are mixed under appropriate conditions of heat and shear, a fused mass is produced. This mass hascertain melt characteristics which can be defined with a to
9、rque rheometer operated under fixed conditions of shear and temperature.The fusion characteristics of a PVC compound are manifest as fusion time, fusion torque, melt torque, melt viscosity, and heat andcolor stability.1 This practice is under the jurisdiction of ASTM Committee D20 on Plastics and is
10、 the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.Current edition approved Nov. 1, 2010Nov. 1, 2018. Published March 2011December 2018. Originally approved in 1969. Last previous edition approved in 20022010 asD2538 02.D2538 02 DOI:10.1520/D2538-02R10.(2010). DOI:10.1520/D
11、2538-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended
12、 only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current v
13、ersionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 A control lot is to be used as a standard against which other test results are to be compared. Te
14、st data are to be evaluatedrelative to the control lot.6. Apparatus6.1 Microprocessor Torque Rheometer,3equipped with a high-shear mixer with roller-style blades, bowl-jacket thermocouple,stock thermocouple, and temperature recorder.NOTE 2A torque rheometer without microprocessor capability can be u
15、sed to perform the fusion, thermal stability, and color hold tests.6.1.1 For flexible and rigid compounds, use a Type 6 roller head with a rotor ratio of 3 Drive: 2 Driven.NOTE 3A Type 5 roller head can also be used, but the data generated cannot be compared with the Type 6 data.6.2 Quick-Loading Po
16、wder Chute or equivalent.6.3 Brass Knife.6.4 Brass Wool or Brush.6.5 Insulated Gloves.6.6 Balance, 500-g minimum capacity, with a 0.1-g sensitivity.6.7 Beaker, stainless steel, 400 mL.6.8 Oven.6.9 Aluminum Foil.6.10 Timer.6.11 Long-Nose Pliers.6.12 Hand-Press Mold.7. Materials7.1 Poly(Vinyl Chloride
17、) Resin.7.2 Filter.7.3 Lubricants.7.4 Plasticizer.7.5 Process-Aid.7.6 Impact Modifier.7.7 Stabilizer.7.8 Pigments.8. Hazards8.1 Do not exceed the power capacity of the instrument, as damage to the mixer or to the torque rheometer may result.8.2 Do not attempt to clean or poke objects into the mixer
18、while it is running.8.3 Gloves with sufficient insulation to enable the operator to handle the hot equipment should be worn when conducting thesetests.9. Fusion Test Method9.1 Compound Preparation:9.1.1 The compound may be beaker-mixed, blended in an intensive mixer or a ribbon blender, or blended a
19、nd pelletized. If thecompound is beaker-mixed, the total weight of the compound should equal the amount charged to the roller-head bowl.9.2 Equipment Preparation:9.2.1 Mount the roller head on the torque rheometer.9.2.2 Select a temperature/rotor speed combination that will permit the test to be com
20、pleted within a reasonable time constraint.Suggested combinations for several types of PVC compound are found in Appendix X2.9.2.3 With the mixer empty and running, zero the recording pen on the chart.3 Suitable equipment may be obtained from C. W. Brabender, 50 E. Wesley St., South Hackensack, NJ 0
21、7606, and Haake Buchler Instruments, 244 Saddle River Rd.,Saddle Brook, NJ 07662.D2538 1829.3 Procedure:9.3.1 Determine the sample size to be added to the mixer, using the following formula:sample size5V 2D! 365%#3specific gravity (1)where:V = volume of mixer bowl without rotors, andD = volume displ
22、acement or rotors.NOTE 4The correct sample size for the mixer is when the fusion curve will duplicate itself. As the mixer wears, it will be necessary to increase thesample size to reproduce a fusion curve equivalent to previous curves.9.3.2 Weigh a sample of the test compound in accordance with 9.3
23、.1. With the mixer running, position the quick-loading chuteon the roller-head mixer and pour in the sample compound. Place the ram into the chute and add the weight. When the torque curveindicates maximum torque has been reached, remove the loading chute and weight.9.3.3 Continue mixing until the m
24、elt torque achieves a steady state.9.3.4 Stop the mixer and open the bowl. Clean the compound from the bowl and blades using the brass knife or wool, or both.9.3.5 Reassemble the mixing bowl and repeat 9.3.2 9.3.4 for additional tests. Since some cooling takes place when cleaningthe bowl, allow suff
25、icient time to confirm that the mixing bowl has reached equilibrium at the test temperature before using again.NOTE 5The quick-loading chute should be at the same temperature at the start of each test. Heat or cool as required.9.4 Interpretation of Torque Rheometer Fusion Test Curve (Fig. 1):9.4.1 F
26、usion TorqueALoading PeakThe point of maximum torque.torque of the unfused, cold raw material.9.4.2 Fusion TimeBMinimumThe time from the point of loading to the point of maximumminimum torque.9.4.3 FSInflection PointThe change in the slope of the curve after the minimum. It will help to characterize
27、 the speed ofthe particle rearrangement (see fusion speed).9.4.4 XMaximumFusion TorqueThe point where the fused material has its maximum torque.9.4.5 EEnd PointUser-defined endpoint where the torque curve is stable and steady.9.4.6 Melt TorqueThe fusion where the torque curve is relatively flat.flat
28、 (not displayed in the graph).A: Loading Peak t: A.X = Fusion TimeB: Minimum v: FS 20 % = Fusion SpeedFS: Inflection PointX: MaximumE: EndFIG. 1 Torque Rheometer Fusion Test CurveD2538 1839.4.7 A.XFusion TimeTime between the loading peak A and the Maximum (fusion Torque) X.9.4.8 FS 620 %Fusion Speed
29、The speed of the progressing fusion of the particles.9.5 ReportReport the following information:9.5.1 The fusion torque to the nearest 100 mg.9.5.1.1 Report to the nearest 25 mg when using a 0 to 1000 scale.9.5.2 The fusion time to the nearest 12 min.9.5.3 The melt torque to the nearest 100 mg.9.5.3
30、.1 Report to the nearest 25 mg when using a 0 to 1000 scale.NOTE 6If the melt torque is not steady, approximate the value and note whether the torque is increasing or decreasing.9.5.4 Temperature of test, rotor revolutions per minute, and sample size used.10. Thermal Stability Test Method10.1 Prepar
31、e the test compound in accordance with 9.1.10.2 Prepare the test equipment in accordance with 9.2.10.3 Procedure:10.3.1 Weigh a sample of the test compound in accordance with 9.3.1. With the mixer running, position the quick-loading chuteon the roller-head mixer and pour in the sample compound. Plac
32、e the ram into the chute and add the weight. When the torque curveindicates fusion, remove the loading chute and weight.10.3.2 Continue running until there is a sudden rise in the torque curve, indicating decomposition of the PVC compound.10.3.3 Stop the mixer and open the bowl. Clean the compound f
33、rom the bowl and blades using the brass knife or wool, or both.10.3.4 Reassemble the mixing bowl and repeat 10.3.1 10.3.3 for additional tests. Confirm that the bowl has reached the testtemperature before starting.10.4 Interpretation of Torque Rheometer Curve (Fig. 1):10.4.1 Compound Heat StabilityT
34、he time from the point of maximum torque (fusion torque) to the point of sudden torqueincrease.10.5 ReportReport the following information:10.5.1 The compound heat stability to the nearest 12 min, and10.5.2 The temperature of test, rotor revolutions per minute, and the sample size used.11. Color-Hol
35、d Stability Test Method11.1 Prepare the test compound in accordance with 9.1.11.2 Prepare the test equipment in accordance with 9.2.11.3 Procedure:11.3.1 Weigh a sample of the test compound in accordance with 9.3.1. With the mixer running, position the quick-loading chuteon the roller-head mixer and
36、 pour in the sample compound. Place the ram into the chute and add the weight. When the torque curveindicates fusion, remove the loading chute and the weight.11.3.2 Using the point of maximum torque (fusion torque) as zero time, remove a sample of the compound at regular timeintervals of 2, 3, or 5
37、min. Stop the rotors and use a pair of long-nose pliers to remove a sample from the bowl. Restart the rotors.Place the compound into a hand press to shape the sample. Trim the sample and return the excess to the mixing bowl.11.3.3 Mount the samples in a sequential time order.11.3.4 Continue sampling
38、 until the desired color change has been observed.NOTE 7Depleting the sample from the bowl can affect the amount of working the compound receives. Select a time sequence that does not removemore than half the sample.11.3.5 Stop the mixer and open the bowl. Clean the compound from the bowl and blades
39、, using the brass knife or wool, or both.11.3.6 Reassemble the mixing bowl and repeat 11.3.1 11.3.5 for additional tests. Confirm that the bowl has reached the testtemperature before starting.11.4 ReportReport the following information:11.4.1 The time to equivalent color change and11.4.2 The tempera
40、ture of test, rotor revolutions per minute, and the sample size used.11.5 Alternative Procedure:11.5.1 Weigh a sample of the test compound in accordance with 9.3.1. With the mixer running, position the quick-loading chuteon the roller-head mixer and pour in the sample compound. Place the ram into th
41、e chute and add the weight. When the torque curveindicates fusion, remove the loading chute and the weight.D2538 18411.5.2 Using the point of maximum torque (fusion torque) as zero time, run the mixer until the compound starts to discolor. Stopthe mixer, remove the contents, and press into a plaque.
42、11.5.3 Clean the bowl and blades and reassemble the mixer.11.5.4 Run additional tests, stopping at the same point in time as 11.5.2.11.5.5 Measure the color of the plaque in a Hunter Colorimeter (or equivalent).11.6 ReportReport the following information:11.6.1 The color number measured on the press
43、ed plaque and11.6.2 The temperature of the test, rotor revolutions per minute, the sample size, and the time as determined in 11.5.2.12. Shear Stability Test Method12.1 Prepare the test compound in accordance with 9.1.12.2 Prepare the test equipment in accordance with 9.2.NOTE 8Use the microprocesso
44、r torque rheometer for this test.12.3 Procedure:12.3.1 Set the microprocessor for the desired temperature and program the revolutions per minute as follows:12.3.1.1 Run at preselected revolutions per minute for ten min.12.3.1.2 Return to 0 r/min.12.3.1.3 Program the speed control to run from 0 to 10
45、0 r/min in 1 min and stop.12.3.2 When the bowl temperature has stabilized, weigh out a sample of the test compound. Position the quick-loading chuteon the roller-head mixer, turn on the torque rheometer, and pour in the sample compound. Place the ram into the chute and addthe weight. When the ram bo
46、ttoms, remove the loading chute.12.3.3 When the sample run is finished, use the microprocessor to plot the torque versus revolutions per minute. Use the plottedcurve for analysis.12.3.4 When the mixer has stopped, open the bowl. Clean the compound from the bowl and blades, using the brass knife orwo
47、ol, or both.12.3.5 Reassemble the mixing bowl and repeat 12.3.1 12.3.5 for additional tests.13. Interpretation of Torque Rheometer Results13.1 Visual Analysis:13.1.1 The first 10 min of the graph represents a standard fusion curve which can be used to determine the fusion time, fusiontorque and melt
48、, or stabilized torque.13.1.2 The torque versus revolutions per minute plot can be used as a relative comparison of shear sensitivity.13.1.3 Bearing in mind that a straight inclined line would denote a Newtonian material, the shear sensitivity can be estimatedby the degree of arc.Alarge arc or loop
49、denotes more shear-sensitive material than does a smaller arc or loop.Avisual observationcan be made to determine the relative shear sensitivity between sample materials.13.2 Technical Analysis:13.2.1 The torque versus revolutions per minute plotted graph can be used in conjunction with the microprocessor software toprovide a shear-sensitivity index number. The software is programmed to give such a number. A higher index number denotes amore shear-sensitive material.13.2.2 The calculation programmed into the software is shown
