1、Designation: E2408 04 (Reapproved 2009)Standard Test Method forRelative Extensional Viscosity of Agricultural Spray TankMixes1This standard is issued under the fixed designation E2408; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, 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 covers the determination of the relativeextensional viscosity or Screen Factor (SF) of
3、dilute agricul-tural spray mixes.1.2 The test can be used for tank mixes containing dis-solved, emulsified or dispersed materials, or mixtures.1.3 Results may be affected by the quality of the water used.Make-up water quality should therefore be specified in thepresentation of results.1.4 Proper saf
4、ety and hygiene precautions must be takenwhen working with pesticide formulations to prevent skin oreye contact, vapor inhalation, and environmental contamina-tion. Read and follow all handling instructions for the specificformulation and conduct the test in accordance with goodlaboratory practice.N
5、OTE 1References to the development of extensional viscosity fromdissolved polymers, extensional viscosity effects on the droplet sizedistribution of sprays, and measurements of screen factor on recirculatedspray mixes containing polymers are available.2,31.5 The values stated in SI units are to be r
6、egarded asstandard. No other units of measurement are included in thisstandard.1.6 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 dete
7、rmine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4D1193 Specification for Reagent WaterE609 Terminology Relating to PesticidesE1116 Test Method for Emulsification Characteristics ofPesticide Emulsifiable Concentrates2.2 CIPAC Documents:CIPAC M
8、onograph 1 (Instructions for the preparation ofhard water)CIPAC Method MT 18.1.1 to 18.1.7 (Instructions for thepreparation of standard waters)3. Terminology3.1 Definitions:3.1.1 screen factor, (SF)the ratio of the flow time of a testfluid (tp) to the flow time of water (tw) through the screenviscom
9、eter apparatus.3.1.2 extensional viscosity, (E)a measure of the resistanceof a fluid to distortion by a stretching force.4. Significance and Use4.1 Extensional viscosity is a measure of the resistance of aliquid to stretching forces, such as those occurring during thedisruption of liquid films and t
10、he formation of sprays used inagriculture and other purposes including painting operations ormetal working. This method for measurement of a ScreenFactor, gives a relative value for extensional viscosity, whichmay be used:4.1.1 To compare the potential for drift control of differentpolymers.4.1.2 To
11、 compare the relative extensional viscosity compo-nent of different spray tank mixtures.4.1.3 To determine the extent of breakdown of polymersolutions used as drift control additives during the recirculationof the solutions through pumps and screens.4.1.4 To use as a parameter in the Spray Drift Tas
12、k ForceModels for droplet size prediction.1This test method is under the jurisdiction of ASTM Committee E35 onPesticides and Alternative Control Agents and is the direct responsibility ofSubcommittee E35.22 on Pesticide Formulations and Delivery Systems.Current edition approved Oct. 1, 2009. Publish
13、ed November 2009. Originallyapproved in 2004. Last previous edition approved in 2004 as E2408 04. DOI:10.1520/E2408-04R09.2Dexter, R. W., “Measurements of Extensional Viscosity of Polymer Solutionsand its Effect on Atomization from a Spray Nozzle,” Atomization and Sprays,Vol6, 1996, pp. 1671913Zhu,
14、H., Dexter, R. W., Fox, R. D., Reichard, D. L., Brazee, R. D., and Okzan,H. E.,“Droplet Size and Viscosity Effects in Recirculated Polymer Spray Solutions,”J. Agric. Engr. Res., Vol 67, 1997, pp. 35454For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
15、e 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 19428-2959, United States.4.2 It should also be noted that many drift co
16、ntrol polymersare irreversibly destroyed during the recirculation of spraymixes by pumping with high shear pumps such as gear orcentrifugal pumps. It is advisable to subject the test mixture tosimilar pumping regimes to simulate practical conditionsbefore carrying out the extensional viscosity test.
17、 Measure-ments of extensional viscosity are the only presently knownmethod of determining the extent of this breakdown propertiesof dilute polymer solutions.4.3 This method is intended to produce a relative value forextensional viscosity. The purpose of the method is to comparethe extensional viscos
18、ity produced by different polymer typesor concentrations of polymer in spray tank mixes.5. Apparatus5.1 List of Materials for Construction of Screen Viscometer:5.1.1 Item 1Fluorinated plastic14 in. (0.635 cm) straightunion, reference SKU-II4, P#D1O77019. Norton PerformancePlastics, 150 Dey Road, Way
19、ne, New Jersey, 07470, USA.5.1.2 Item 2Cut five (5)14 in. diameter discs (see 5.2)from 100 mesh (150 m aperture) USAStandard Testing Sieve,ASTM E11 specification, stainless steel plain weave screen, soas to fit tightly into the14 in. plastic union.5.1.3 Item 3Glass 25 mL pipette, VWR catalog #7102(1
20、999) or equivalent. External diameter of the tube below thebulb of the pipette = 0.82 cm. Cut off the lower part of thepipette at a point 2.5 cm below the bulb. Round off the sharpedges of the tube with a flame.5.1.4 Item 4Silicone rubber tubing, flexible, for use as asleeve to join a glass tube (It
21、em 5) to the lower end of thepipette (Item 3).5.1.5 Item 5Glass tube, cut froma2mLpipette, Kimax#37000, or equivalent (American Scientific catalog #P4140-2).Dimensions of tube are: length = 3 cm; outside diameter = 0.62cm. Round off the sharp ends of the tube in a flame.NOTE 2Appropriate safety prec
22、autions should be taken when using anopen flame for rounding the ends of the glass tubes.5.2 Assembly of Screen ViscometerRefer to Fig. 1, whichshows the arrangement of the separate items of equipment, andFig. 2, which shows the placement of the screen pack in theplastic union.5.2.1 Push the five st
23、ainless screen discs, one at a time, intothe14 in. (0.635 cm) plastic union. Push each screen down tothe central lug in the union, using a piece of14 in. glass tubing.Ensure that the last of the 5 screens fits tightly into the plastictube to keep the pack of screens well compacted and fixed inplace.
24、5.2.2 Push the silicone rubber sleeve (Item 4) on to thelower end of the pipette tube (Item 3). Leave approximately 0.8cm of the silicone tube projecting beyond the glass.5.2.3 Push the short glass tube (Item 5) into the plastic unionfirmly and press down on the pack of screens. Screw on the endcap
25、of the union to retain the position of the screen pack.Ensure that the Teflon cone supplied with the union is fittedproperly, to provide a leak tight seal. About 0.6 cm of the glasstube should protrude from the end cap of the union.5.2.4 Push together the glass tube protruding from the endcap, into
26、the silicone rubber sleeve attached to the pipette.Check the alignment of the pipette and screen pack forstraightness.5.3 Other Accessories Required:5.3.1 Two 500 mL beakers.5.3.2 A stand and clamp to hold the pipette firmly in avertical position.5.3.3 A stopwatch, reading to 0.01 s.5.3.4 A 200 mesh
27、 USA Standard Testing (75 m aperture)stainless steel sieve, 4 in. diameter.5.3.5 A pipette bulb, or preferably, a low vacuum suctiondevice (see 7.2.2).FIG. 1 Diagram of ApparatusE2408 04 (2009)26. Test Materials6.1 Deionized Water, filtered through a 200 mesh (75 maperture) stainless steel screen, f
28、or use in rinsing the apparatusand as a standard fluid for calibrating the screen pack.6.2 Test Fluid(s), as required to be tested.7. Procedure7.1 Preparation of Test Fluids for use in Screen Viscometer:7.1.1 Dilute the formulation in the appropriate standardwater to the desired spray concentration.
29、 Pass approximately500 mL of the liquid so prepared through a 200 mesh USAStandard stainless steel sieve, to remove poorly dispersedaggregates or gels. The test can be run with as little as 200 mLof the test fluid. The temperature of the fluid should be kept atstandard temperature, preferably in a c
30、onstant temperatureroom.NOTE 3Dilute solutions of high molecular weight polymers oftenrequire prolonged dissolution to allow for complete swelling and disso-lution, especially if provided as solids. Note also that excessive stirring orshearing by pumping can cause degradation of the polymer molecule
31、sresulting in a decrease in molecular weight and viscosity. If the solution isdrawn up into the screen viscometer too rapidly, it may be degraded. It hasbeen found useful to use a vacuum device that provides a low andconsistent suction to the pipette.7.2 Calibration of Screen Viscometer:NOTE 4Water
32、is used as the calibration fluid.7.2.1 Place 400 mL of deionized water in a 500 mL beakerand adjust to the required temperature. (A temperature of 23 to25C has been used, but any temperature at which the screenfactor is required may be used. The calibrating fluid (water)and the test fluid must be ru
33、n at the same temperature).7.2.2 Lower the screen viscometer assembly into the water,clamp the pipette in a vertical position, and draw up water intothe pipette through the screen pack, by applying vacuum to thetop of the pipette. Draw the water up to a point about 2 in.above the upper timing mark.7
34、.2.3 Raise the pipette tip above the surface of the liquidabout 2 cm, and fix in position using the clamp, so that theliquid will fall freely from the pipette in air during draining.Then allow the water to run out of the pipette freely undergravity. Start the stopwatch as the meniscus passes the upp
35、ertiming mark, and stop the watch when the meniscus passes thetop edge of the silicone rubber sleeve. The efflux time is shortand practice may be needed to obtain consistent results. Recordthe efflux time.7.2.4 Repeat the measurement a total of 5 times, andaverage the efflux times. This is the efflu
36、x time for water (tw).Record the temperature of the room and fluid.7.3 Testing Spray Fluids:7.3.1 Completely drain the screen viscometer after calibra-tion with deionized water.7.3.2 Draw up the test fluid (as in 7.2.2) and record theefflux time for the fluid. Repeat the measurements a total of 5tim
37、es.7.3.3 Record the average time as the efflux time of the fluid(tp).7.3.4 If a second test fluid is to be run, then the screenviscometer should be thoroughly rinsed with filtered deionizedwater and drained between tests.NOTE 5If inconsistent results are obtained it is probably due totrapped air. Ai
38、r bubbles can be released by tapping the pipette bulb andscreen pack.8. Report8.1 Report the following information:8.1.1 Average efflux time for water, tw.8.1.2 Average efflux time for the test fluid, tp.FIG. 2 Diagram of ApparatusE2408 04 (2009)38.1.3 Calculate the average value of Screen Factor:Sc
39、reen Factor SF!5 (1)average efflux time of the test fluidaverage efflux time for water at specified temperature5tptw8.1.4 In all cases the water quality should be specified, inparticular the concentration and chemistry of the dissolvedsolids content of the liquid. Any unusual treatment of the sprayl
40、iquid, for example pretreatment by pumping, should bereported.9. Precision and Bias9.1 PrecisionThe reproducibility of this test method asdetermined by statistical analysis of results obtained fromseveral laboratories in a round robin was as follows, averagedover single operators:For water flow time
41、s (tw),Standard deviation of tw= 0.7 to 4 % for a single operatorFor polymer solution flow times (tp),Standard deviation of tp= 0.8 to 3 % for a single operatorFor Screen Factor values (SF),Standard deviation of SF = 1.5 to 6 % for a single operator9.1.1 Repeatability is expressed in terms of the st
42、andarddeviation from the mean in several tests. The existing data fromthe round robin indicate that the standard deviation of ScreenFactor for measurements of several different fluids conductedby all operators in aggregate is approximately 15 %.NOTE 6In the round robin procedure adopted, each operat
43、or wasrequired to construct his own apparatus, so that some differences in resultsfrom different operators would be expected, increasing the standarddeviation between operators.9.2 BiasThere exist other methods for the determinationof extensional viscosity. Extensional viscosity is dependentupon the
44、 strain rate for most polymer solutions, an differentmethods of measurement may give different extensional vis-cosity values, because of variations in the strain rate applied inthe equipment. This method may provide values for ScreenFactor that do not agree with the results of extensionalviscosity f
45、rom other methods. This method operates at rela-tively low extensional strain rates and may therefore be biasedtowards low extensional strains, so that the values of exten-sional viscosity may be relatively low, compared with, forexample, the Rheometrics RFX instrument. However, themethod gives good
46、 comparisons between fluids and is moresensitive than other methods, especially at low polymer con-centrations. Reports of the use of this method and its relevanceto spray droplet size control are available (see Section 2,Referenced Documents).ASTM International takes no position respecting the vali
47、dity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subj
48、ect to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquar
49、ters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832
