1、Designation: G21 09Standard Practice forDetermining Resistance of Synthetic Polymeric Materials toFungi1This standard is issued under the fixed designation G21; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers determination of the effect of fungion the properties of synthetic polymeric materials in the formof molded
3、 and fabricated articles, tubes, rods, sheets, and filmmaterials. Changes in optical, mechanical, and electrical prop-erties may be determined by the applicable ASTM methods.1.2 The values stated in SI units are to be regarded as thestandard. The inch-pound units given in parentheses are forinformat
4、ion only.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 determine the applica-bility of regulatory limitations prior to use.2. Ref
5、erenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power FrequenciesD150 Test Methods for AC Loss Characteristics and Per-mittivity (Dielectric Constant) of Solid Electrical Insula-tionD2
6、57 Test Methods for DC Resistance or Conductance ofInsulating MaterialsD495 Test Method for High-Voltage, Low-Current, DryArcResistance of Solid Electrical InsulationD618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD747 Test Method for Apparent Be
7、nding Modulus of Plas-tics by Means of a Cantilever BeamD785 Test Method for Rockwell Hardness of Plastics andElectrical Insulating MaterialsD1003 Test Method for Haze and Luminous Transmittanceof Transparent PlasticsD1708 Test Method for Tensile Properties of Plastics byUse of Microtensile Specimen
8、sE96/E96M Test Methods for Water Vapor Transmission ofMaterialsE308 Practice for Computing the Colors of Objects byUsing the CIE System2.2 TAPPI Standard:Test Method T 451-CM-484 Flexural Properties of Paper32.3 Federal Standards:FED STD 191 Method 5204 Stiffness of Cloth, Directional;Self Weighted
9、Cantilever Method4FED STD 191 Method 5206 Stiffness of Cloth Drape andFlex; Cantilever Bending Method43. Summary of Practice3.1 The procedure described in this practice consists ofselection of suitable specimens for determination of pertinentproperties, inoculation of the specimens with suitable org
10、an-isms, exposure of inoculated specimens under conditionsfavorable to growth, examination and rating for visual growth,and removal of the specimens and observations for testing,either before cleaning or after cleaning and reconditioning.NOTE 1Since the procedure involves handling and working withfu
11、ngi, it is recommended that personnel trained in microbiology performthe portion of the procedure involving handling of organisms andinoculated specimens.4. Significance and Use4.1 The synthetic polymer portion of these materials isusually fungus-resistant in that it does not serve as a carbonsource
12、 for the growth of fungi. It is generally the othercomponents, such as plasticizers, cellulosics, lubricants, stabi-lizers, and colorants, that are responsible for fungus attack onplastic materials. To asses materials other than plastics, use ofthis test method should be agreed upon by all parties i
13、nvolved.It is important to establish the resistance to microbial attack1This practice is under the jurisdiction of ASTM Committee G03 on Weatheringand Durability and is the direct responsibility of Subcommittee G03.04 onBiological Deterioration.Current edition approved Dec. 1, 2009. Published March
14、2010. Originallyapproved in 1961. Last previous edition approved in 2002 D1924 96(02).Redesignated G21 in 1970 (Reapproved 1990). DOI: 10.1520/G0021-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta
15、ndards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Technical Association of the Pulp and Paper Industry (TAPPI),15 Technology Parkway South, Norcross, GA 30092, http:/www.tappi.org.4Available from Standardization Documents Order Desk, Bldg. 4 S
16、ection D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.under conditions favorable for such attack, namely, a tempera-ture of 2 to 38C (35 to 100F) and a relative humidity o
17、f 60to 100 %.4.2 The effects to be expected are as follows:4.2.1 Surface attack, discoloration, loss of transmission(optical), and4.2.2 Removal of susceptible plasticizers, modifiers, andlubricants, resulting in increased modulus (stiffness), changesin weight, dimensions, and other physical properti
18、es, anddeterioration of electrical properties such as insulation resis-tance, dielectric constant, power factor, and dielectric strength.4.3 Often the changes in electrical properties are due prin-cipally to surface growth and its associated moisture and to pHchanges caused by excreted metabolic pro
19、ducts. Other effectsinclude preferential growths caused by nonuniform dispersionof plasticizers, lubricants, and other processing additives.Attack on these materials often leaves ionized conductingpaths. Pronounced physical changes are observed on productsin film form or as coatings, where the ratio
20、 of surface tovolume is high, and where nutrient materials such as plasticiz-ers and lubricants continue to diffuse to the surface as they areutilized by the organisms.4.4 Since attack by organisms involves a large element ofchance due to local accelerations and inhibitions, the order ofreproducibil
21、ity may be rather low. To ensure that estimates ofbehavior are not too optimistic, the greatest observed degree ofdeterioration should be reported.4.5 Conditioning of the specimens, such as exposure toleaching, weathering, heat treatment, etc., may have significanteffects on the resistance to fungi.
22、 Determination of these effectsis not covered in this practice.5. Apparatus5.1 GlasswareGlass or plastic vessels are suitable forholding specimens when laid flat. Depending on the size of thespecimens, the following are suggested:5.1.1 For specimens up to 75 mm (3 in.) in diameter, 414 by414 in. (10
23、0 by 100 mm) plastic boxes5or 150-mm (6-in.)covered Petri dishes, and5.1.2 For 75 mm (3 in.) and larger specimens, such astensile and stiffness strips, large Petri dishes, trays of borosili-cate glass, or baking dishes up to 400 by 500 mm (16 by 20 in.)in size, covered with squares of window glass.5
24、.2 IncubatorIncubating equipment for all test methodsshall maintain a temperature of 28 to 30C (82.4 to 86F) anda relative humidity not less than 85 %. Automatic recording ofwetand dry-bulb temperature is recommended.6. Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused
25、 in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specification are available.6Other grades may beused, provided it is first ascertained that the reagent
26、is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean distilled water or water ofequal or higher purity.6.3 Nutrient-Salts AgarPrepare this medium by dissolv-ing
27、 in 1 L of water the designated amounts of the followingreagents:Potassium dihydrogen orthophosphate (KH2PO4) 0.7 gMagnesium sulfate (MgSO47H2O) 0.7 gAmmonium nitrate (NH4NO3) 1.0 gSodium chloride (NaCl) 0.005 gFerrous sulfate (FeSO47H2O) 0.002 gZinc sulfate (ZnSO47H2O) 0.002 gManganous sulfate (MnS
28、O4H2O) 0.001 gAgar 15.0 gPotassium monohydrogen orthophosphate (K2HPO4) 0.7 g6.3.1 Sterilize the test medium by autoclaving at 121C(250F) for 20 min. Adjust the pH of the medium by theaddition of 0.01 N NaOH solution so that after sterilization thepH is between 6.0 and 6.5.6.3.2 Prepare sufficient m
29、edium for the required tests.6.3.3 Nutrient Salts Broth Prepare using the formula in6.3, omitting the agar. Broth may be filter sterilized to avoid theprecipitation of the salts that occurs with autoclaving.6.4 Mixed Fungus Spore Suspension:NOTE 2Since a number of other organisms may be of specific
30、interestfor certain final assemblies or components, such other pure cultures oforganisms may be used if agreed upon by the purchaser and themanufacturer of the plastic. Reference (1)7illustrates such a choice.6.4.1 Use the following test fungi in preparing the cultures:Fungi ATCC No.AMYCO No.BAsperg
31、illus niger 9642 386Penicillium pinophilumC11797 391Chaetomium globosum 6205 459Gliocladium virens 9645 365Aureobasidium pullulans 15233 279cAAvailable from American Type Culture Collection, 12301 Parklawn Drive,Rockville, MD 20852.BAvailable from Mycological Services, P.O. Box 1056, Crawfordsville,
32、 IN 47933.CHistorically known as P. funiculosm.6.4.1.1 Maintain cultures8of these fungi separately on anappropriate medium such as potato dextrose agar. The stockcultures may be kept for not more than four months atapproximately 3 to 10C (37 to 50F). Use subculturesincubated at 28 to 30C (82 to 86F)
33、 for 7 to 20 days inpreparing the spore suspension.6.4.1.2 Prepare a spore suspension of each of the five fungiby pouring into one subculture of each fungus a sterile 10-mLportion of water or of a sterile solution containing 0.05 g/L of5Available from Tri-State, Inc., Henderson, KY.6Reagent Chemical
34、s, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National F
35、ormulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.7The boldface numbers given in parentheses refer to a list of references at theend of the practice.8Historically known as P. funiculosm.G21092a nontoxic wetting agent such as sodium dioctyl sulfosucci-nate. Use a sterile platinum or
36、 nichrome inoculating wire togently scrape the surface growth from the culture of the testorganism.6.4.2 Pour the spore charge into a sterile 125-mL glass-stoppered Erlenmeyer flask containing 45 mL of sterile waterand 10 to 15 solid glass beads, 5 mm in diameter. Shake theflask vigorously to libera
37、te the spores from the fruiting bodiesand to break the spore clumps.6.4.3 Alternatively, the spore charge can be poured into asterile glass tissue grinder and gently ground to break up thespore clumps and liberate the spores from the fruiting bodies.6.4.4 Filter the shaken or ground suspension throu
38、gh a thinlayer of sterile glass wool in a glass funnel into a sterile flaskin order to remove mycelial fragments.6.4.5 Centrifuge the filtered spore suspension aseptically,and discard the supernatant liquid. Resuspend the residue in analiquot of sterile water and centrifuge.6.4.6 If large mycelia fr
39、agments or clumps of agar weredislodged during the harvesting, wash the spores in this mannerthree times to remove possible nutrient carryover from theoriginal cultures. Dilute the final washed residue with sterilenutrient-salts solution (see Note ) in such a manner that theresultant spore suspensio
40、n shall contain 1 000 000 6 200 000spores/mL as determined with a counting chamber.6.4.7 Repeat this operation for each organism used in thetest and blend equal volumes of the resultant spore suspensionto obtain the final mixed spore suspension.6.4.8 The spore suspension may be prepared fresh each d
41、ayor may be held in the refrigerator at 3 to 10C (37 to 50F) fornot more than four days.7. Viability Control7.1 With each daily group of tests place each of three piecesof sterilized filter paper, 25 mm (1 in.) square, on hardenednutrient-salts agar in separate Petri dishes. Inoculate these withthe
42、spore suspension by spraying the suspension from asterilized atomizer9so that the entire surface is moistened withthe spore suspension. Incubate these at 28 to 30C (82 to 86F)at a relative humidity not less than 85 % and examine themafter 14 days incubation. There shall be copious growth on allthree
43、 of the filter paper control specimens. Absence of suchgrowth requires repetition of the test.8. Test Specimens8.1 The simplest specimen may be a 50 by 50-mm (2 by2-in.) piece, a 50-mm (2-in.) diameter piece, or a piece (rod ortubing) at least 76 mm (3 in.) long cut from the material to betested. Co
44、mpletely fabricated parts or sections cut from fabri-cated parts may be used as test specimens. On such specimens,observation of effect is limited to appearance, density ofgrowth, optical reflection or transmission, or manual evaluationof change in physical properties such as stiffness.8.2 Film-form
45、ing materials such as coatings may be testedin the form of films at least 50 by 25 mm (2 by 1 in.) in size.Such films may be prepared by casting on glass and strippingafter cure, or by impregnating (completely covering) filterpaper or ignited glass fabric.8.3 For visual evaluation, three specimens s
46、hall be inocu-lated. If the specimen is different on two sides, three specimensof each, face up and face down, shall be tested.NOTE 3In devising a test program intended to reveal quantitativechanges occurring during and after fungal attack, an adequate number ofspecimens should be evaluated to estab
47、lish a valid value for the originalproperty. If five replicate specimens are required to establish a tensilestrength of a film material, the same number of specimens shall beremoved and tested for each exposure period. It is to be expected thatvalues of physical properties at various stages of funga
48、l attack will bevariable; the values indicating the greatest degradation are the mostsignificant (see 4.4). Reference (2) may be used as a guide.9. Procedure9.1 InoculationPour sufficient nutrient-salts agar intosuitable sterile dishes (see 5.1) to provide a solidified agar layerfrom3to6mm(18 to14 i
49、n.) in depth. After the agar issolidified, place the specimens on the surface of the agar.Inoculate the surface, including the surface of the test speci-mens, with the composite spore suspension by spraying thesuspension from a sterilized atomizer9so that the entire surfaceis moistened with the spore suspension.9.2 Incubation Conditions:9.2.1 IncubationCover the inoculated test specimens andincubate at 28 to 30C (82 to 86F) and not less than 85 %relative humidity.NOTE 4Covered dishes containing nutrient agar are considered tohave the desired hum
