1、Designation: D 3795 00a (Reapproved 2006)Standard Test Method forThermal Flow, Cure, and Behavior Properties of PourableThermosetting Materials by Torque Rheometer1This standard is issued under the fixed designation D 3795; the number immediately following the designation indicates the year oforigin
2、al adoption or, in the case 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. Scope*1.1 This test method covers the apparatus, and a specific testmetho
3、d, including the evaluation of results required for thedetermination of the thermal flow and cure behavior propertiesof pourable thermosetting materials.1.2 This test method can be used:1.2.1 As a control for the development and production ofpourable thermosetting materials and to measure the differ
4、entproperties (for example, melting behavior, cure behavior, etc.)as well as the influence of various additives and fillers in anygiven formulations, and1.2.2 Verify the uniformity of different production batchesof the same formulation.1.3 The values are stated in SI units.1.4 This standard does not
5、 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 regulatory limitations prior to use. Specific precau-tions are given in Secti
6、on 7.NOTE 1There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 1898 Practice for Sampling of Plastics3E 691 Practice for Co
7、nducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions of Terms Specific to This StandardFor thepurpose of this test method, the following definitions apply,(see Fig. 1):3.1.1 flow and cure behaviorthe flow behavior is repre-sented by the recorded t
8、orque curve from the loading peak(Point t1), to the torque minimum (Point t5). The cure behavioris represented by the recorded torque curve from the torqueminimum (Point t5) to the torque maximum (Point t4). The rateof curing is represented by the slope of the torque curve.3.1.2 timethe residence ti
9、me at torque t53 X, where X isa factor (preferably 1.3) is tv(s). To determine tv, draw a lineat t53 X parallel with the time axis. The intersection of thisline with the left branch of the curve is t2. The intersection ofthis line with the right branch of the curve is t3:tv5 t32 t2units are seconds
10、s! (1)3.1.2.1 DiscussionDepending on the manufacturer of theequipment, the software analysis program for the designatedvalues in this test method may differ (t1, t2, etc).3.1.2.2 DiscussionUpon agreement between interestedparties, the value of X may be changed and be listed in anyreport.3.1.3 reside
11、nce time or duration of plastic life (t2 t3)theresidence time is represented by a section of the recordedtorque curve in which the molten material causes the lowesttorque, s.3.1.4 total cure time (t4 t0)time from when the materialis loaded into the mixer chamber up to complete cure, s.3.1.5 torque:1
12、This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 on Thermal Properties(Section D20.30.08).Current edition approved March 15, 2006. Published April 2006. Originallyapproved in 1979. Last previous edition approved in 200
13、0 as D 3795 00a.2For referenced ASTM standards, 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.3Withdrawn.1*A Summary of Changes section app
14、ears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.5.1 initial torque (t1)the initial high torque peak oncematerial is loaded into the mixer chamber. Sometimes referredto as the loading peak, Nm (Newt
15、on-meters).3.1.5.2 minimum torque (t5)the lowest point on the torquecurve representing maximum fluxing of material, Nm.3.1.5.3 final torque or cure peak (t4)the final maximumtorque value representing the final cure of material, Nm.4. Summary of Test Method4.1 A sample of thermosetting material is ch
16、arged into thetemperature controlled mixer/measuring head in which thematerial is compacted, melted, cross-linked, hardened, andcrushed under constant shear.5. Significance and Use5.1 The continuous recording of torque and temperaturewhile going through these various stages can be used to predictthe
17、 behavior of the material during processing.5.2 The torque rheometer test has two important functions.First, it is a means to predict flow/viscosity and cure charac-teristics of pourable thermosetting compounds. For example,the test provides useful data to predict the processibility of amaterial in
18、a particular molding method. This information isalso useful to optimize process conditions for a particularmaterial such as the minimum pressure to fill a mold and thetime to cure a part.Asecond capability of the test is to providea graphic record of the batch-to-batch uniformity of themolding compo
19、und.6. Apparatus6.1 Torque Rheometer, with a mixing bowl.6.1.1 The torque rheometer shall be equipped with a drivemotor with a load-independent speed stability of 60.5 % of thetop rotor speed.6.1.2 The recording device selected shall be capable ofrecording the measurable variables of torque, stock t
20、empera-ture, and rotation per minute (RPM) as a function of time. Therheometer should also be equipped with a real time RPMindicator.6.1.3 For the measurement, a surface hardened laboratoryinternal mixer is used, specified by a bowl volume of 25, 30 or60 cm3, that can be attached to the above mentio
21、ned torquerheometer. Either a set of triangular or roller blades shall beused counter-rotating with a speed ratio of 3:2 (left to right).(The mixer bowl may be heated with a circulated liquidtemperature controlled by a thermostat or electrically with atleast two heating zones (see Note 2).NOTE 2Only
22、 the results obtained with identical measuring systemscan be compared with one another. In this context, the mixer type, type ofheating/cooling and loading weight used are of decisive importance.6.1.4 Liquid heated mixers shall be equipped with a circu-lation pump that has a capacity of at least 24
23、L/min at a backpressure of approximately 500 mbars. The heat transfer me-dium shall be stabilized silicone oil, with a maximum viscosityof 20 mm2/s at 25C. The oil temperature shall be monitoredby a device which has a resolution of 0.2C or better.6.1.5 Electrically heated mixer bowls shall have a mi
24、nimumof one independent electric controller and a maximum of twoindependent electric controllers that utilize modern controltechniques and algorithms. These controllers shall provide bothheating and cooling cycles. The temperature control ensemblesthat include the sensor, controller and actuators sh
25、all beaccurate to within 2.0C throughout their working range.Reported values shall have a precision of 0.2C or better.6.1.6 The torque recording ensemble shall be accurate to0.25 % of the reading.6.1.7 For feeding flowable or granular sample materials aloading device shall be used. For feeding other
26、 coarse materi-als, a pressure ram actuated manually or pneumatically shall beused. The loading chute has to be mounted onto the mixer, witha ram and eithera5or2kgweight or with an adjustablepneumatic cylinder (see Note 2).6.1.8 For recording of the stock temperature during themeasuring process, the
27、 temperature measuring device ismounted from below into the bottom of the measuring mixer insuch a way that it penetrates 1.5 mm into the mixer bowl. Thestock temperature versus time, is recorded simultaneouslytogether with the torque curve.6.1.9 Soft Brass Spatula or Stiff Brass Bristle Cleaning To
28、ol.7. Hazards7.1 Do not exceed the rated power of the instrument asdamage to the mixer or to the torque rheometer may result.7.2 Do not attempt to clean or insert objects into the mixerwhile it is running.7.3 Use adequate exhausts and safety devices necessary tomeet applicable safety codes.7.4 Use i
29、nsulated gloves to protect operator from hot mixersurface.7.5 Refer to manufacturers operating instructions.NOTE 1Top curve associated with temperature axis; bottom curveassociated with torque axis.FIG. 1 Torque Rheometer CurveD 3795 00a (2006)28. Sampling8.1 A batch of compound shall be considered
30、as a unit ofmanufacture as prepared for shipment and may consist of amanufacturers blend of one or more production runs ofmaterial.8.2 Suitable methods of sampling shall follow PracticeD 1898. A 400-g sample will be sufficient for tests required.8.3 Crush any compound in a preform state to a particl
31、e sizethat would pass through the loading chute.9. Sample Selection, Handling and Use for RheometerStandardization9.1 SelectionThe selection of the sample should be deter-mined by the use for which it is intended. If it is to be anintralaboratory standardization sample, (for example in amaterial com
32、pounders laboratory), the sample should bechosen to closely approximate the materials expected to betested. (For compounders having a wide range of productplasticities it is recommended that one sample for eachmaximum torque range be available.) For interlaboratorystandardization, the sample should
33、be of the product type beingmolded.9.1.1 Handling:9.1.1.1 Once the selection of the sample has been agreedupon among the interested parties it shall be gathered insufficient quantity that the supply of sample for each laboratorycan be expected to outlast the need to change the mixing heador blades b
34、y about 50 % of the life of the head or blades. Thisis to avoid running out of standardization standard at the sametime as an equipment change takes place on the rheometer (seeNote 3).NOTE 3The determination for wear of the measuring mixer andblades shall be measured volumetrically. The equipment ma
35、nufacturershall provide the procedure and values for the individual measuringmixers.9.1.1.2 It is recommended that the sample be broken up intopreweighed charges, the charge weight being based on thespecific gravity of the sample and the size of the mixing headin use on the respective rheometers. Th
36、ese should be heat-sealed in individual polyethylene pouches. If the samples are ofany compound which has a defined shelf-life, they should bestored at, or near freezing in order to protect their plasticityproperties from changing. If the samples have indefiniteshelf-life, they should be stored belo
37、w the temperature atwhich volatile material could be driven off due to excessivevapor pressure.9.1.1.3 Samples stored in this manner should be allowed afull 24-h to reach equilibrium temperature with standardlaboratory conditions of 23 6 2C before removing fromstorage pouches for standardization tes
38、ting.9.1.2 Samples should be used to test the standardization ofthe respective rheometers at agreed upon intervals of operation.It is recommended that the standardization be tested at leastevery 120 h of operation. Operating time is defined not as thetotal testing time; but rather as the total elaps
39、ed time that therheometer is powered up. This would be once per week for afull time, five day per week laboratory operation. The samplesshould be used two at a time, where the first sample tested willbe used to condition the instrument mixing head and blades,and the second sample will be used as act
40、ual standardizationdata.9.1.2.1 It is recommended that sample pouches be drawnfrom storage five at a time for conditioning to ambientconditions. The first will be used for rheometer conditioning,the second for standardization testing, and the remaining beused for additional standardization testing i
41、n the event that theinstrument needs to be adjusted, or restandardized. If the extrathree samples are not needed they may be safely returned tostorage if they have not been opened.9.2 CalibrationTo ensure reliability of this test method, itis essential that the torque rheometer be calibrated periodi
42、callyusing a reference material.Acontrol chart indicating the resultsof these calibrations should be kept. Entire equipment calibra-tions shall be done when data from a reference materialcalibration versus the control chart, causes the instrumentationto be suspect.9.2.1 Equipment CalibrationThe torq
43、ue, temperaturecontrol, and RPM systems shall be calibrated using national orinternational regulatory body traceable standards and proce-dures.9.2.2 Record all “as found” measured values versus ac-cepted values before making any attempts at corrective action.All“ as left” measured values should be r
44、ecorded upon com-pleting any adjustments.9.2.3 Upon completion of the calibration, provide a Certifi-cate of Calibration. This document shall include the datavalues, traceability of each standard used, and a statisticalestimation of the uncertainties associated with each procedureand standard versus
45、 national or international regulatory bodystandards.10. Procedure10.1 Select a mixer temperature that corresponds to themean processing temperature of the material to be tested:Material Type (granular) Suggested Temperature, CAlkyd 150Crosslineable polyethylene 145, 175DAP 150Epoxy 150, 175Phenolic
46、125, 150Polyester 150Silicone 140Silicone-epoxy 14010.2 Adjust the required mixer temperature at the bath andthe circulation thermostat or at the temperature controller forthe electrically heated mixer. Condition the measuring mixer atthis temperature until the mixer has reached equilibrium.10.3 Sta
47、rt the torque rheometer before starting the first testand obtain a uniform temperature in the system. Make sure thatthe mixing blades are rotating during this time.10.4 Weigh the test charge with a precision of 60.1 g and toan accuracy of 0.5 % of the total sample mass for eachmeasurement. Depending
48、 on the density of the material, theoptimum charge for the measuring mixer may vary. Eq 2 is areference for determining a good load charge:G 5 0.7 3 V 3 p (2)D 3795 00a (2006)3where:G = the sample mass, in kilograms,V = the free mixer volume, in liters,P = the density of sample material, in kilogram
49、s per liter,and (density in accordance with Test Method D 792).The density of the sample material shall be given with anaccuracy of6 0.03 kg/L.10.5 Start the drive of the torque rheometer and adjust therotor speed to 40 RPM. Charge the running mixer with thesample quickly and as uniformly as possible using the loadingchute and the pressure ram, respectively. Loading shall becompleted within 20 s. As soon as all material has been loadedinto the mixer, place the 5 or 2 kg weight onto the ram of theloading chute in order to close the mixer. If a pneumaticl
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