1、Designation: C581 15 An American National StandardStandard Practice forDetermining Chemical Resistance of Thermosetting ResinsUsed in Glass-Fiber-Reinforced Structures Intended forLiquid Service1This standard is issued under the fixed designation C581; the number immediately following the designatio
2、n indicates the year oforiginal adoption or, in the case 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.This standard has been approved for use by agenc
3、ies of the U.S. Department of Defense.1. Scope1.1 This practice is designed to evaluate, in an unstressedstate, the chemical resistance of thermosetting resins used inthe fabrication of reinforced thermosetting plastic (RTP) lami-nates. This practice provides for the determination of changesin the p
4、roperties, described as follows, of the test specimensand test reagent after exposure of the specimens to the reagent:hardness of specimens, weight change thickness, appearance ofspecimens, appearance of immersion media, and flexuralstrength and modulus.1.1.1 This practice is also useful to evaluate
5、 other factors,such as surfacing veils and the effect of resin additives, on thechemical resistance of the resin.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand
6、are not considered standard.NOTE 1There is no known ISO equivalent to this standard.1.3 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
7、 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-alsD883 Terminology Relating to PlasticsD2563 Practice for Classifying Vis
8、ual Defects in Glass-Reinforced Plastic Laminate PartsD2583 Test Method for Indentation Hardness of Rigid Plas-tics by Means of a Barcol ImpressorD2584 Test Method for Ignition Loss of Cured ReinforcedResins3. Terminology3.1 Definitions of Terms:3.1.1 For definitions of terms associated with plastic
9、materials, see Terminology D883.4. Significance and Use4.1 The results obtained by this practice shall serve as aguide in, but not as the sole basis for, selection of a thermo-setting resin used in an RTP structure. No attempt has beenmade to incorporate into the practice all the various factors tha
10、twill potentially affect the serviceability of an RTP structurewhen subjected to chemical environments. These factors willpotentially include stress, different resin-to-glass ratios, andmultiple veils.5. Apparatus5.1 Hardness Testing InstrumentThis shall be as describedin Test Method D2583.5.2 Flexu
11、ral Properties Testing Apparatus, in accordancewith Test Methods D790.5.3 Thickness MeasurementA micrometer suitable formeasurement to 0.001 in. (0.025 mm).5.4 Containers, of sufficient size, capacity, and inertness toallow total immersion of reinforced thermosetting plasticspecimens in the specific
12、 corrosives chosen for testing. Thesecontainers shall, when necessary, be capable of maintainingliquid levels of volatile solutions, that is, solvents. This can beaccomplished by the use of reflux condensers.5.5 Heating ApparatusA constant temperature oven, heat-ing mantle, or liquid bath capable of
13、 maintaining temperature1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.23 on Reinforced Plastic PipingSystems and Chemical Equipment.Current edition approved Dec. 1, 2015. Published January 2016. Originallyapproved in 196
14、5. Last previous edition approved in 2008 as C581 03(2008)1.DOI: 10.1520/C0581-15.2For 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 pag
15、e onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1within range of 64.0F (62.2C). Take proper precautions ifthe corrosives selected are flammable liquids.5.6 Analytical Balance, suitable for accurate weighing to0.001
16、 g.6. Reagents6.1 The test media shall consist of the reagents or solutionsto which the RTP laminates are to be exposed.7. Test Specimens7.1 Standard LaminatesPrepare standard fiber-reinforcedlaminates using identical reinforcement in all of the laminates.The laminates shall be constructed of the fo
17、llowing materials:7.1.1 Surfacing Mat (Veil)A thin mat of fine fibers usedprimarily to produce a smooth, resin-rich surface on a rein-forced plastic. The surfacing veil helps determine the thicknessof the resin-rich layer, reduces microcracking and provides anon-wicking chemicallyresistant layer. Th
18、e surfacing veilshall be compatible with the resin, and manufactured withuniform fiber distribution and non-bundled fibers. The dry veillayer(s) shall be a minimum 10 mils in thickness and producea 10 to 15 mil resin-saturated veil layer per 10 mils of dry veil.To eliminate the surfacing veil as a v
19、ariable in corrosion tests,prepare each laminate within a test group with the samesurfacing veil.7.1.2 Chopped Strand MatType E glass fiber with sizingand binder compatible with the resin. It is acceptable to useother glass fiber compositions, but using such alternate com-positions shall be consider
20、ed as variables for comparison to thestandard.7.1.2.1 Note that this practice applies to E-CR glass fiber,which is a type of E glass fiber. If the E glass fiber material isof the E-CR type that information shall be identified in the testreport.7.1.3 ResinCatalyzed and promoted in accordance withthe
21、resin manufacturers recommendation.NOTE 2It is acceptable to add fillers, such as antimony trioxide forimproved fire performance or thixotropes for viscosity control, but it ispossible that this will detract from the corrosion resistance of the testlaminate.7.2 Dimensions and General PropertiesThe l
22、aminatesshall conform to the required dimensions and general proper-ties of 7.2 and be fabricated in accordance with 7.3.7.2.1 Laminate SizeA suitable laminate size has beenfound to be 26 by 33 in. (660 by 838 mm) after trimming. Thislaminate size is not restrictive and other dimensions areacceptabl
23、e.7.2.2 ThicknessThe thickness of the cured standard lami-nate shall be between 0.120 and 0.140 in. (3.05 and 3.56 mm).7.2.3 Reinforcement ContentThe glass fiber and bindershall be 4.73 6 0.47 oz/ft2(three layers of 1.5 oz/ft2choppedstrand mat 4.5 oz/ft2having a nominal binder content of 3.5 %and tw
24、o layers of 10 mil surfacing mat 0.23 oz/ft2having anominal binder content of 7 %)determined by preweighingthe materials prior to construction of the laminate. This isequivalent to 23.6 weight % (12.5 volume %) glass fiber whenusing a resin having a cured specific gravity of 1.15. Such alaminate wil
25、l have a thickness of 0.125 in. (3.18 mm). The useof resins having different specific gravities will result indifferent weight percentages of glass fiber, but the volumepercentage of glass fiber will remain the same. When usingsynthetic organic fiber surfacing veil, the glass content shall be4.50 6
26、0.45 oz/ft2( three layers of 1.5oz/ft2chopped strandmat having a nominal binder content of 3.5 %).7.2.4 HardnessThe hardness shall be at least 90 % of thatof a fully-cured clear casting of the resin, or of a similarlyconstructed laminate as defined by the resin manufacturer.Hardness shall be determi
27、ned in accordance with s5.1. Notethat the use of synthetic veil will result in significantly lowerhardness values. The hardness value will vary with the type ofresin and number of plies of synthetic veil. The resin manu-facturer needs to be contacted for the allowable Barcolhardness value of a lamin
28、ate containing synthetic veils with thespecific resin.7.2.5 Laminate ConditionThe laminate shall meet Accep-tance Level I of Table I of Practice D2563.7.3 Fabrication of Standard LaminateThe sequence oflay-up shall be as follows:7.3.1 Apply catalyzed resin and a 10-mil (0.25-mm) surfac-ing mat on a
29、flat surface covered with plastic release film ortreated with a suitable release agent and roll to distribute resin.NOTE 3Use the following formula as a guide to determine the totalweight of resin to be used. This is equivalent to 12.5 volume % glass fiberin the laminate. Grams resin equals grams gl
30、ass fiber material per 7.2.3times 2.82 G. Where G equals specific gravity of cured resin. It isacceptable to use excess resin due to loss by adhering to mixingcontainers, rollers, and other factors. A suggested amount of excess resinis 10 to 15 % by weight.7.3.2 Follow with three plies of 1.5 oz/ft2
31、chopped strandmat and resin. Roll after each ply to distribute and wet-out thechopped strand mat. Rolling with a serrated roller is acceptableafter each ply to remove entrapped air but it shall be done inaccordance with 7.3.4. The mat weight shall be within 65%of1.5 oz/ft2upon weighing the full 26 b
32、y 33-in. cut (660 by838-mm) piece, (or other full dimension used, 7.2.1.).NOTE 4Cut chopped strand mat so that the 26-in. dimension is acrossthe width of the roll and the 33-in. dimension is along the machinedirection of the mat. Mat weight variation will most commonly occuracross the width of the m
33、at. If a wide roll of mat, 52 in. (1320 mm) orgreater, is used, place the two plies of mat in the laminate such that thecenter cut of one ply is placed over the outside edge of the second ply. Ifnarrower width mat is used, reverse the second ply 180 in the machinedirection and lay it on top of the f
34、irst ply to minimize weight variations.7.3.3 Follow with a 10-mil (0.25-mm) surfacing mat as in7.3.1.7.3.4 Remove the air by rolling over the surface with aserrated metal or plastic roller. Take care not to expel enoughresin to raise the glass content above the permissible maxi-mum. The laminate is
35、considered within the range of allowablelevels of resin and glass if the thickness of the laminate iswithin 0.120 and 0.140 in. (3.05 and 3.56 mm), as described in7.2.2.7.3.5 After the lay-up is completed, cover the laminate witha plastic release film to prevent air inhibition or to provide auniform
36、 smooth glossy surface, or both. Carefully smoothdown to remove entrapped air.C581 152NOTE 5It is acceptable to use any convenient method for theapplication of the release film. Regardless of how it is applied, it is criticalthat any entrapped air between the film and the laminate be entirelyremoved
37、. One method of application is done by previously wrapping thefilm around a metal rod. Starting at one edge of the laminate, slowly unrollthe film from the rod, keeping a bead of resin ahead of the rod as you crossthe laminate. Any entrapped air remaining can be removed by rubbing atongue depressor
38、across the release film surface. Carefully pull the filmtaut and fasten at the edges to prevent wrinkling of the film. Placing stops(neoprene has been found to be suitable) around the edges of the laminateand passing a heavy metal roller over the laminate helps to insure uniformcontrolled thickness.
39、7.3.6 Cure as recommended by the resin manufacturer. Thecure schedule shall be reported.7.3.7 Trim edges as required.7.4 Record of Standard Laminate ConstructionRecord theproperties of the standard laminate as follows:7.4.1 HardnessDetermine Barcol hardness on the strip asdescribed in 7.2.4 in accor
40、dance with Test Method D2583.7.4.2 Laminate ConditionsVisually examine the laminate.The laminate shall meet Acceptance Level I of Table 1 ofPractice D2563.7.4.3 If the laminate meets the requirements of thisspecification, retain the laminate sections for preparation of testspecimens.NOTE 6The major
41、criteria for accepting a laminate is thickness andnot glass content. If glass content is desired, cut eight 1 by 1 in. specimensfrom the center of the laminate and test in accordance with Test MethodD2584.7.5 Individual Test Specimens:7.5.1 Specimens for immersion in test solutions shall beapproxima
42、tely 4 by 5 in. (101.6 by 127 mm), cut from thestandard laminate.7.5.2 Identity of specimens shall be maintained by suitablemeans.7.5.3 Cut edges and drilled holes, if used for suspension,shall be sanded smooth and coated with paraffinated resin.7.5.4 The number of specimens required is dependent on
43、 thenumber of test solutions to be employed, the number ofdifferent temperatures at which testing is performed, and thenumber of test intervals. In addition, at least two 4 by 5 in.(101.6 by 127 mm) specimens shall be available for test (see8.4) following the curing period, prior to immersion.8. Pro
44、cedure8.1 Measurement of SpecimensImmediately following thecuring period, measure the thickness of the specimens to thenearest 0.001 in. (0.025 mm) at the geometric center of each ofthe intended 1 by 3 in. (25.4 by 76.2 mm) specimens that willbe cut for flexural tests after the completed exposures.
45、Measurethe weight of the specimens to the nearest 0.01 g. Thesethickness and weight measurements shall also be used forcomparison against thickness and weight measurements afterthe completed exposures.8.2 ExposureFollowing the curing period, as specified in7.3.6, prior to immersion, record a brief d
46、escription of the colorand surface appearance of the coupons and the color and theclarity of the test solution. The total number of coupons percontainer is not limited except by the ability of the container tohold the coupons without touching each other or the container.The coupons must always be co
47、mpletely immersed. Couponsshall be vertical, parallel, and spaced a minimum of 0.25 in.(6.35 mm) apart. There shall be a minimum of 0.50 in. (12.7mm) between coupon edges and the container or the liquidsurface. Place the closed container in a constant temperatureoven adjusted to the required tempera
48、ture or in a suitablyadjusted liquid bath. Examine the coupons after 30, 90, 180days, and one year of immersion or other time intervals asrequired to determine the rate of attack.8.2.1 Discard the test solution and replace it with freshsolution as often as necessary to maintain original compositiona
49、nd concentration.As a minimum, solutions known to be stableneed to be replaced at the end of each test period.8.3 Cleaning and Examination After ExposureClean thecoupon and dry by blotting with a paper towel. Cold tap wateris normally used for specimen cleaning. If other cleaningagents are used, verify that they do not attack the resin beingtested.8.3.1 Note any indication of surface attack on a coupon, anydiscoloration of the test solution, and the formation of anysediment.8.3.2 After final blotting, immediately measure the couponthickness to the ne
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