1、Designation: D2578 09D2578 17Standard Test Method forWetting Tension of Polyethylene and Polypropylene Films1This standard is issued under the fixed designation D2578; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t 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 measurement of the wetting tension of a polyethylene or polypropylene film surface in contac
3、twith drops of specific test solutions in the presence of air.1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversionsto inch-pound units that are provided for information only and are not considered standard.NOTE 1This test metho
4、d and the specified reagents were specifically developed for polyethylene and polypropylene films. It is possible to utilize thistest method and the specified reagents for films composed of other polymers, but this can affect the surface energies of the gas-liquid and solid-liquidinterfaces, which w
5、ill affect the contact angle and wetting tension. The applicability and significance for use of non-polyolefin materials must beestablished by the user.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of th
6、is 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 2This test method is equivalent to ISO 8296.1.4 This international standard was
7、 developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced D
8、ocuments2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method2.2 ISO Standard:ISO 8296 PlasticsFilm and SheetingDetermination of Wetting Tension33. Summary of Test Method3.1 In this tes
9、t method drops of a series of mixtures of formamide and ethyl Cellosolve4 of gradually increasing surface tensionare applied to the surface of the polyethylene or polypropylene film until a mixture is found that just wets the film surface. Thewetting tension of the polyethylene or polypropylene film
10、 surface will be approximated by the surface tension of this particularmixture.4. Significance and Use4.1 When a drop of liquid rests on the surface of a solid, and a gas is in contact with both, the forces acting at the interfacesmust balance. These forces can be represented by surface energies act
11、ing in the direction of the surfaces and it follows that:GLcos5GS2SL (1)1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.19 on Film, Sheeting, and MoldedProducts.Current edition approved Sept. 1, 2009Dec. 15, 2017. Pu
12、blished September 2009January 2018. Originally approved in 1967. Last previous edition approved in 20082009as D2578 - 08.D2578 - 09. DOI: 10.1520/D2578-09.10.1520/D2578-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Ann
13、ual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.4 Registered trademark of Union Carbide Corp. for ethylene g
14、lycol monoethyl ether.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 not be technically possible to adequately depict all changes accurately, ASTM recommends that u
15、sers 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 end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
16、hohocken, PA 19428-2959. United States1where: = angle of contact of the edge of the drop with the solid surface,GL = surface energy of the gas - liquid interface,GS = surface energy of the gas - solid interface, andSL = surface energy of the solid - liquid interface. = angle of contact of the edge o
17、f the drop with the solid surface,GL = surface energy of the gas - liquid interface,GS = surface energy of the gas - solid interface, andSL = surface energy of the solid - liquid interface.4.1.1 The right side of the above equation (the difference between the surface energies of the gas - solid and
18、solid - liquidinterfaces) is defined as the wetting tension of the solid surface. It is not a fundamental property of the surface but depends oninteraction between the solid and a particular environment.4.1.2 When the gas is air saturated with vapors of the liquid, GL will be the surface tension of
19、the liquid. If the angle of contactis 0 the liquid is said to just wet the surface of the solid, and in this particular case (since cos = 1) the wetting tension of thesolid will be equal to the surface tension of the liquid.4.2 The ability of polyethylene and polypropylene films to retain inks, coat
20、ings, adhesives, etc., is primarily dependent uponthe character of their surfaces, and can be improved by one of several surface-treating techniques. These same treating techniqueshave been found to increase the wetting tension of a polyethylene or a polypropylene film surface in contact with mixtur
21、es offormamide and ethyl Cellosolve in the presence of air. It is therefore possible to relate the wetting tension of a polyethylene ora polypropylene film surface to its ability to accept and retain inks, coatings, adhesives, etc. The measured wetting tension of aspecific film surface can only be r
22、elated to acceptable ink, coating, or adhesive retention through experience. Wetting tension initself is not a completely acceptable measure of ink, coating, or adhesive adhesion.NOTE 3A wetting tension of 35 dynes/cm or higher has been generally found to reveal a degree of treatment normally regard
23、ed as acceptable fortubular film made from Type 1 polyethylene and intended for commercial flexographic printing. It is, however, possible that some other level of wettingtension may be required to indicate the acceptability of polyethylene films made by other processes, or from other types of polye
24、thylene, or intended forother uses.At the present date, insufficient experience has been gained to state a generally acceptable level of wetting tension for polypropylene films forcommercial flexographic printing.5. Interferences5.1 Since the wetting tension of a polyethylene or polypropylene film i
25、n contact with a drop of liquid in the presence of air isa function of the surface energies of both the air - film and film - liquid interfaces, any trace of surface-active impurities in theliquid reagents or on the film may affect the results. It is, therefore, important that the portion of the fil
26、m surface to be tested notbe touched or rubbed, that all equipment be scrupulously clean, and that reagent purity be carefully guarded. Glass apparatus inparticular is likely to be contaminated with detergents having very strong surface tension reducing ability unless specificprecautions are taken t
27、o ensure their absence such as cleaning with chromic-sulfuric acid and rinsing with distilled water.6. Apparatus6.1 Cotton-Tipped Wooden Applicators, approximately 150 mm (6 in.) in length.6.2 Burets, two, 50-mL.6.3 Bottles, 100-mL, with caps and labels.7. Reagents and Materials7.1 Prepare mixtures
28、of reagent grade formamide (HCONH2) and reagent grade ethyl Cellosolve (CH3CH2OCH2CH2OH) in theproportions shown in Table 1 for the integral values of wetting tension in the range over which measurements are to be made. Forextremely precise work, mixtures for determining fractional values of wetting
29、 tension may be made up by interpolating betweenthe concentrations shown in Table 1.NOTE 4Although the mixtures of ethyl Cellosolve and formamide used in this test method are relatively stable, exposure to extremes of temperatureor humidity should be avoided.D2578 1727.2 If desired, add to each of t
30、he formamide ethyl Cellosolve mixtures a very small amount of dye of high tinctorial value. Thedye used should be of such color as to make drops or thin films of the solutions clearly visible on the surface of polyethylene orpolypropylene film and must be of such chemical composition that it will no
31、t measurably affect the wetting tension of the solutionsin the concentration used.57.3 Fully prepared mixtures of these reagents in varying concentrations are available from a number of commercial sources.Pens containing these mixtures are also commercially available. However, correlations between t
32、hese options and freshly preparedsolutions have not been established.NOTE 5Care must be taken when handling pens. Prolonged exposure to the atmosphere, temperature or humidity extremes, exposure to contaminants,or use beyond the stated expiration date will change their characteristics creating a pot
33、ential for erroneous results.8. Hazards8.1 Formamide may cause skin irritation and is particularly dangerous in direct contact with the eyes. Safety goggles shouldbe worn when making up new test mixtures.8.2 Ethyl Cellosolve is a highly flammable solvent.8.3 Both ethyl Cellosolve and formamide are t
34、oxic and pose exposure risks. Consult the applicable MSDS Safety Data Sheets(SDS) before use and ensure that the appropriate Personal Protective Equipment (PPE) is used, especially when preparing newsolutions.8.4 All tests should be performed with adequate ventilation.9. Sampling9.1 The minimum amou
35、nt of film required for this test depends upon the skill of the operator. This usually amounts to onesample across the entire width of a roll in order to obtain a representative value.9.2 Extreme care must be taken to prevent the surface of the film sample from being touched or handled in the areas
36、upon whichthe test is to be made.9.3 Usually it will be adequate to make one determination at each location 14, 12, 34 of the way across the width of the film,to arrive at an average value for the sample or to determine when treatment is uneven.5 “DuPont Victoria Pure Blue BO” at a maximum concentra
37、tion of 0.03 % has been found satisfactory.TABLE 1 Concentration of Ethyl CellosolveFormamideMixtures Used in Measuring Wetting Tension ofPolyethylene and Polypropylene FilmsFormamide,Volume %Ethyl Cellosolve,A%Wetting Tension,Bdynes/cm0 100.0 302.5 97.5 3110.5 89.5 3219.0 81.0 3326.5 73.5 3435.0 65
38、.0 3542.5 57.5 3648.5 51.5 3754.0 46.0 3859.0 41.0 3963.5 36.5 4067.5 32.5 4171.5 28.5 4274.7 25.3 4378.0 22.0 4480.3 19.7 4583.0 17.0 4687.0 13.0 4890.7 9.3 5093.7 6.3 5296.5 3.5 5499.0 1.0 56A Cellosolve is the registered trademark of Union Carbide Corp. for ethylene glycolmonoethyl ether.B Measur
39、ed under conditions of 23 2C and 50 5 % relative humidity.D2578 17310. Conditioning10.1 ConditioningCondition the test specimens at 2362C (73.463.6F) and 50610 % relative humidity for not less than40 h prior to test in accordance with ProcedureAof Practice D618 unless otherwise specified by agreemen
40、t or the relevantASTMmaterial specification. In cases of disagreement, the tolerances shall be 61C (61.8F) and 65 % relative humidity.10.2 Test ConditionsConduct the tests at 2362C (73.463.6F) and 50610 % relative humidity unless otherwise specifiedby agreement or the relevant ASTM material specific
41、ation. In cases of disagreement, the tolerances shall be 61C (61.8F) and65 % relative humidity.NOTE 6In specific cases, such as control testing, where the conditioning requirements cannot be met and the data are of direct assistance to theoperation, other conditioning procedures can be used and reco
42、rded in the report.11. Procedure11.1 Wet the very tip of a cotton applicator with one of the mixtures. Use only a minimum amount of liquid as an excess ofreagent can affect the end point of the test.11.2 Spread the liquid lightly over an area of approximately 6.5 cm2 (1 in.2) of the test specimen. D
43、o not try to cover a largerarea lest there be insufficient liquid to give complete coverage.11.3 Note the time required for the continuous film of liquid formed in 11.2 to break up into droplets. If the continuous filmholds for 2 s or more, proceed to the next higher surface tension mixture, but if
44、the continuous film breaks into droplets in lessthan 2 s, proceed to the next lower surface mixture.Aclean, new cotton applicator must be used each time to avoid contaminationof the solutions (even for successive dips into the same solution).NOTE 7The solution is considered as wetting the test speci
45、men when it remains intact as a continuous film of liquid for at least 2 s. The “reading”of the liquid film behavior should be made in the center of the liquid film. Shrinking of the liquid film about its periphery does not indicate lack of wetting.Breaking of the liquid film into droplets within 2
46、s indicates lack of wetting. Severe peripheral shrinkage may be caused by too much liquid being placedupon the film surface. Experience with the test will give excellent insight into “reading” the liquid film behavior.11.4 Proceeding in the direction indicated by the results of 11.3, continue repeat
47、ing 11.1 through 11.3 until it is possible to selectthe ethyl Cellosolve-formamide mixture that comes nearest to wetting the film surface for exactly 2 s. The surface tension of thismixture in dynes per centimetre is called the wetting tension of the polyethylene or polypropylene film specimen.NOTE
48、8Since the surface tension of the formamide/ethyl cellosolve solutions can change, for example, through evaporation of one or bothcomponents, or through contamination, and is dependent upon temperature, the actual surface tension of the solution that wet the film for exactly 2 sshould be measured. T
49、his can be accomplished very simply with a surface tensiometer.611.5 Experience with this test has shown that on occasion erroneous wetting tension results can be obtained when the finalwetting tension is determined by working progressively to lower surface tension mixtures when practicing 11.1 11.4. It isrecommended that the test analyst should check the reported wetting tension of the film by working progressively to higher surfacetension mixtures.12. Report12.1 Report the average value of the wetting tension of each sample to the
