1、Designation: D1238 10D1238 13Standard Test Method forMelt Flow Rates of Thermoplastics by ExtrusionPlastometer1This standard is issued under the fixed designation D1238; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the rate of extrusion of molten thermoplastic resins using an extrusionpl
3、astometer. After a specified preheating time, resin is extruded through a die with a specified length and orifice diameter underprescribed conditions of temperature, load, and piston position in the barrel. Four procedures are described. Comparable resultshave been obtained by these procedures in in
4、terlaboratory round-robin measurements of several materials and are described inSection 15.1.2 Procedure A is used to determine the melt flow rate (MFR) of a thermoplastic material. The units of measure are grams ofmaterial/10 minutes (g/10 min). It is based on the measurement of the mass of materia
5、l that extrudes from the die over a givenperiod of time. It is generally used for materials having melt flow rates that fall between 0.15 and 50 g/10 min (see Note 1).1.3 Procedure B is an automatically timed measurement used to determine the melt flow rate (MFR) as well as the melt volumerate (MVR)
6、 of thermoplastic materials. MFR measurements made with Procedure B are reported in g/10 minutes. MVRmeasurements are reported in cubic centimetres/ten minutes (cm3/10 min). Procedure B measurements are based on thedetermination of the volume of material extruded from the die over a given period of
7、time. The volume is converted to a massmeasurement by multiplying the result by the melt density value for the material (see Note 2). Procedure B is generally used withmaterials having melt flow rates from 0.50 to 1500 g/10 min.1.4 Procedure C is an automatically timed measurement used to determine
8、the melt flow rate (MFR) of polyolefin materials.It is generally used as an alternative to Procedure B on samples having melt flow rates greater than 75 g/10 min. Procedure Cinvolves the use of a modified die, commonly referred to as a “half-die,” which has half the height and half the internal diam
9、eterof the standard die specified for use in Procedures A and B thus maintaining the same length to diameter ratio. The test procedureis similar to Procedure B, but the results obtained with Procedure C shall not be assumed to be half of those results produced withProcedure B.1.5 Procedure D is a mu
10、lti-weight test commonly referred to as a “Flow Rate Ratio” (FRR) test. Procedure D is designed toallow MFR determinations to be made using two or three different test loads (either increasing or decreasing the load during thetest) on one charge of material. The FRR is a dimensionless number derived
11、 by dividing the MFR at the higher test load by theMFR at the lower test load. Results generated from multi-weight tests shall not be directly compared with results derived fromProcedure A or Procedure B.NOTE 1Polymers having melt flow rates less than 0.15 or greater than 900 g/10 min may be tested
12、by the procedures in this test method; however,precision data have not been developed.NOTE 2Melt density is the density of the material in it molten state. It is not to be confused with the standard density value of the material. See Table3.NOTE 3This test method and ISO 1133 address the same subjec
13、t matter, but differ in technical content.1.6 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of theuser of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limita
14、tionsprior to use.1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.30 on Thermal Properties (SectionD20.30.08).Current edition approved Feb. 1, 2010Aug. 1, 2013. Published March 2010August 2013. Originally approved in
15、 1965. Last previous edition approved in 20042010 asD1238 - 04c.D1238 - 10. DOI: 10.1520/D1238-10.10.1520/D1238-13.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may no
16、t be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the en
17、d of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD3364 Test Method for Flow Rates for
18、Poly(Vinyl Chloride) with Molecular Structural ImplicationsD4000 Classification System for Specifying Plastic MaterialsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM
19、Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.D1238 1322.2 ANSI Standard:B46.1 on Surface Texture32.3 ISO Standard:ISO 1133 Determination of the Melt-Mass Flow Rate (MFR) and the Melt Volume-
20、Flow Rate (MVR) of Thermoplastics33. Terminology3.1 General:3.1.1 Definitions are in accordance with Terminology D883 unless otherwise specified.4. Significance and Use4.1 This test method is particularly useful for quality control tests on thermoplastics.4.2 The data produced by this test method se
21、rves to indicate the uniformity of the flow rate of the polymer as made by anindividual process. It is not to be used as an indication of uniformity of other properties without valid correlation with data fromother tests.4.3 The flow rate obtained with the extrusion plastometer is not a fundamental
22、polymer property. It is an empirically definedparameter critically influenced by the physical properties and molecular structure of the polymer and the conditions ofmeasurement. The rheological characteristics of polymer melts depend on a number of variables. It is possible that the values ofthese v
23、ariables occurring in this test will differ substantially from those in large-scale processes, which would result in data thatdoes not correlate directly with processing behavior.4.4 Measure the flow rate of a material using any of the conditions listed for the material in 8.2X4.1. For many material
24、s, thereare specifications that require the use of this test method, but with some procedural modifications that take precedence whenadhering to the specification. Therefore, it is advisable to refer to that material specification before using this test method. Table1 in Classification D4000 lists t
25、he ASTM materials standards that currently exist. An alternative test method for poly (vinylchloride) (PVC) compounds is found in Test Method D3364.4.5 Additional characterization of a material can be obtained if more than one condition is used. In the case that two or moreconditions are employed, a
26、 Flow Rate Ratio (FRR) is obtained by dividing the flow rate at one condition by the flow rate at anothercondition. Procedure D provides one method to measure more than one condition in a single charge.4.6 Frequently, variations in test technique, apparatus geometry, or test conditions, which defy a
27、ll but the most careful scrutiny,exist, causing discrepancies in flow rate determinations. A troubleshooting guide is found in Appendix X2 and it is a resource tobe used to identify sources of test error.5. Apparatus5.1 Extrusion Plastometer (Alternative NamesMelt Indexer, Melt Flow Indexer):NOTE 4O
28、lder plastometers that were manufactured in accordance with “design specifications” detailed in previous revisions of this test method (preD1238 - 04c) are deemed to be acceptable, as long as they meet the dimensional and performance specifications stated in this section.NOTE 5Relatively minor chang
29、es in the design and arrangement of the component parts have been shown to cause differences in results amonglaboratories. For the best interlaboratory agreement, it is important that the design adhere closely to the description herein; otherwise, it should bedetermined that modifications do not inf
30、luence the results. Refer to Fig. 1.5.1.1 The apparatus shall be a dead-weight piston plastometer consisting of a thermostatically controlled heated steel cylinderwith a bore that contains a die at the lower end, and a weighted piston operating within the cylinder. The essential features of theplast
31、ometer, illustrated in Figs. 1 and 2, are described in 5.2-5.12. The bore of the extrusion plastometer shall be properly alignedin the vertical direction (see Appendix X1). All dimensional measurements shall be made when the article being measured is at23 6 5C.5.2 CylinderThe cylinder shall be 50 mm
32、 6 10 mm in diameter, 115 to 180 mm in length with a smooth, straight bore9.5504 6 0.0076 mm in diameter. The cylinder bore shall be manufactured in a way that produces a finish approximately 12 rmsor better in accordance with ANSI B46.1. Means shall be provided to monitor the temperature inside the
33、 bore.5.3 Die (Orifice):5.3.1 Standard DieThe outside diameter of the die shall be such that it will fall freely to the bottom of the hole in the cylinder.The orifice of the die shall have a smooth straight bore 2.095 6 0.005 mm in diameter and shall be 8.000 6 0.025 mm in length(see Fig. 2). The bo
34、re of the orifice and its finish are critical. It shall have no visible drill or other tool marks and no detectableeccentricity. The bore of the orifice shall be manufactured by techniques known to produce finishes approximately 12 rms or betterin accordance with ANSI B46.1.3 Available from American
35、 National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.D1238 1335.3.2 “Half” DieUsed for Procedure C. When testing polyolefins with a MFR of 75 or greater (using the standard die), analternate die has shown to improve the reproducibility of results by
36、 reducing the flow rate of these materials. The outside diameterof the die shall be such that it will fall freely to the bottom of the hole in the cylinder. The orifice shall have a smooth straightbore 1.048 6 0.005 mm in diameter and shall be 4.000 6 0.025 mm in length (see Fig. 2A). The bore of th
37、e orifice and its finishare critical. It shall have no visible drill or other tool marks and no detectable eccentricity. The bore of the orifice shall bemanufactured by techniques known to produce finishes approximately 12 rms or better in accordance withANSI B46.1 (Note Note6). No spacer shall be u
38、sed with this die.NOTE 6Recommended die material is tungsten carbide. Also satisfactory are steel, synthetic sapphire, and cobalt-chromium-tungsten alloy. Whensofter materials are used, it will be necessary to conduct critical dimensional checks and visual inspections on the die more often.5.4 Pisto
39、n:5.4.1 The piston shall be made of steel. There shall be insulation at the top as a barrier to heat transfer from the piston to theweight. The piston shall be prevented from rubbing on the bore. Most commercially available instruments use a loose fitting metalguide sleeve, but other methods are acc
40、eptable. The weight of the sleeve shall not be considered as part of the test load. The land(foot) of the piston shall be 9.4742 6 0.0076 mm in diameter and 6.35 6 0.10 mm in length. Above the land, the piston shall beFIG. 1 General Arrangement of Extrusion Plastometer (See Sec-tion 5.)FIG. 2 Detail
41、s of Extrusion PlastometerD1238 134relieved to 9.0 mm in diameter (see Fig. 2). The piston land shall be manufactured by techniques known to produce finishesapproximately 12 rms in accordance with ANSI B46.1. If corrosion is a problem, the piston or piston land, if removable, shall bemade of corrosi
42、on resistant material.5.4.2 For procedure A, the piston shall be scribed with two reference marks 4 mm apart in such fashion that when the lowermark coincides with the top of the cylinder, guide sleeve or other suitable reference point, the bottom of the piston is 48 mm abovethe top of the die (see
43、Fig. 1) and the timed test run shall start within these two reference marks. The targeted starting point shallbe 46 6 2mm above the upper face of the die. (see Fig. 1).5.4.3 The combined weight of piston and load shall be within a tolerance of 60.5 % of the selected load.5.5 Temperature Control Syst
44、em:5.5.1 The equipment shall have the capability of heating and maintaining the temperature inside the bore of the cylinder inaccordance with the requirements specified in Table 1 throughout the duration of the test.5.5.2 The preferred method for calibrating the temperature is to use a temperature s
45、ensor assembly having a sensor with at leastan accuracy of 60.08C at 200C and a 20 6 0.5-mm long brass tip press fit on the end of the sensor. The diameter of the brasstip shall closely match the diameter of the die and the length of the active measuring length of the temperature sensor (seeAppendix
46、 X3).5.5.3 Temperatures shall be verified with the bottom of the temperature sensor at 10 and 75 6 1 mm above the upper face ofthe die and at each test temperature, without touching the die. Allow at least four minutes for equilibrium of temperature to bereached for each position. Temperature variat
47、ion shall be determined over a minimum of 15 minutes. When using the “half” die,the temperature indicating device shall be calibrated as stated in Table 1 except temperatures are measured at 79 6 1 mm and 146 1 mm above the upper surface of the die.5.5.4 An alternative method is to insert the temper
48、ature sensor without a brass tip into the melt from the top of the cylinder sothat it is 10 and 75 6 1 mm above the upper face of the die.5.5.5 The temperature sensor and readout equipment used for calibration of the extrusion plastometer shall be traceable to anational standard (for example, NIST).
49、5.6 Timing Device/SystemFor ProcedureA, a timing device with an accuracy of 0.1 s shall be used. For Procedures B, C, andD, an automatic timing system shall measure and time piston movement within the specified travel range. The requirements of theautomatic timing system shall be as follows:5.6.1 Sense and indicate the piston travel time within 60.01 s.5.6.2 Measure piston travel within 60.4 % of the nominal selected value (see 10.7) for use in the flow rate calculations.5.6.3 Operate within a fixed portion of the cylinder. This is defined as the portion of the
