1、Designation: G 21 96 (Reapproved 2002)Standard Practice forDetermining Resistance of Synthetic Polymeric Materials toFungi1This standard is issued under the fixed designation G 21; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice covers deter
3、mination of the effect of fungion the properties of synthetic polymeric materials in the formof molded 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
4、 SI units are to be regarded as thestandard. The inch-pound units given in parentheses are forinformation 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 safe
5、ty and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power Frequencies2D 150 Test Metho
6、ds for A-C Loss Characteristics andPermittivity (Dielectric Constant) of Solid Electrical Insu-lation2D 257 Test Methods for D-C Resistance or Conductance ofInsulating Materials2D 495 Test Method for High-Voltage, Low-Current, DryArc Resistance of Solid Electrical Insulation2D 618 Practice for Condi
7、tioning Plastics for Testing3D 638 Test Method for Tensile Properties of Plastics3D 747 Test Method for Apparent Bending Modulus ofPlastics by Means of a Cantilever Beam3D 785 Test Method for Rockwell Hardness of Plastics andElectrical Insulating Materials3D 1003 Test Method for Haze and Luminous Tr
8、ansmittanceof Transparent Plastics3D 1708 Test Method for Tensile Properties of Plastics byUse of Microtensile Specimens3E96 Test Methods for Water Vapor Transmission of Mate-rials4E 308 Practice for Computing the Colors of Objects byUsing the CIE System52.2 TAPPI Standard:Test Method T 451-CM-484 F
9、lexural Properties of Paper62.3 Federal Standards:FED STD 191 Method 5204 Stiffness of Cloth, Directional;Self Weighted Cantilever Method7FED STD 191 Method 5206 Stiffness of Cloth Drape andFlex; Cantilever Bending Method73. Summary of Practice3.1 The procedure described in this practice consists of
10、selection of suitable specimens for determination of pertinentproperties, inoculation of the specimens with suitable organ-isms, exposure of inoculated specimens under conditionsfavorable to growth, examination and rating for visual growth,and removal of the specimens and observations for testing,ei
11、ther before cleaning or after cleaning and reconditioning.NOTE 1Since the procedure involves handling and working withfungi, it is recommended that personnel trained in microbiology performthe portion of the procedure involving handling of organisms andinoculated specimens.4. Significance and Use4.1
12、 The synthetic polymer portion of these materials isusually fungus-resistant in that it does not serve as a carbonsource 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 on
13、1This 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 Jan. 10, 2002. Published May 2002. Originallypublished as D 1924 61. Last previous edition D 1924 90.
14、 Redesignated G 21 in1970 (Reapproved 1990).2Annual Book of ASTM Standards, Vol 10.01.3Annual Book of ASTM Standards, Vol 08.01.4Annual Book of ASTM Standards, Vol 04.06.5Annual Book of ASTM Standards, Vol 06.01.6Available from Technical Association of the Pulp and Paper Industry, Technol-ogy Park/A
15、tlanta, P.O. Box 105113, Atlanta, GA 30348.7Available from Standardization Documents Order Desk, Bldg. 4 Section 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.plastic mat
16、erials. It is important to establish the resistance tomicrobial attack under conditions favorable for such attack,namely, a temperature of 2 to 38C (35 to 100F) and a relativehumidity of 60 to 100 %.4.2 The effects to be expected are as follows:4.2.1 Surface attack, discoloration, loss of transmissi
17、on(optical), and4.2.2 Removal of susceptible plasticizers, modifiers, andlubricants, resulting in increased modulus (stiffness), changesin weight, dimensions, and other physical properties, anddeterioration of electrical properties such as insulation resis-tance, dielectric constant, power factor, a
18、nd 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 products. Other effectsinclude preferential growths caused by nonuniform dispersionof plasticizers, lubricants, and o
19、ther 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 of surface tovolume is high, and where nutrient materials such as plasticiz-ers and lubricants continue to diffus
20、e 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 ofreproducibility may be rather low. To ensure that estimates ofbehavior are not too optimistic, the greatest observed degree of
21、deterioration 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. Determination of these effectsis not covered in this practice.5. Apparatus5.1 GlasswareGlass or plastic vessels a
22、re 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. (100 by 100 mm) plastic boxes8or 150-mm (6-in.)covered Petri dishes, and5.1.2 For 75 mm (3 in.) and larger specimens,
23、 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.5.2 IncubatorIncubating equipment for all test methodsshall maintain a temperature of 28 to 30C (82.4 to 86F) anda
24、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 in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of
25、the Commit-tee on Analytical Reagents of the American Chemical Society,where such specification are available.9Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of W
26、aterUnless otherwise indicated, referencesto water shall be understood to mean distilled water or water ofequal purity.6.3 Nutrient-Salts AgarPrepare this medium by dissolv-ing in 1 L of water the designated amounts of the followingreagents:Potassium dihydrogen orthophosphate (KH2PO4) 0.7 gMagnesium
27、 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 (MnSO4H2O) 0.001 gAgar 15.0 gPotassium monohydrogen orthophosphate (K2HPO4) 0.7 g6.3.1 Sterilize the test medium by autoclaving
28、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 medium for the required tests.6.4 Mixed Fungus Spore Suspension:NOTE 2Since a number of other organisms may be of specific in
29、terestfor 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)10illustrates such a choice.6.4.1 Use the following test fungi in preparing the cultures:Fungi ATCC No.AMYCO No.BAspergi
30、llus 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,
31、IN 47933.CHistorically known as P. funiculosm.6.4.1.1 Maintain cultures11of 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)
32、 for 7 to 20 days inpreparing the spore suspension.6.4.2 Prepare a spore suspension of each of the five fungi bypouring into one subculture of each fungus a sterile 10-mLportion of water or of a sterile solution containing 0.05 g/L ofa nontoxic wetting agent such as sodium dioctyl sulfosucci-nate. U
33、se a sterile platinum or nichrome inoculating wire togently scrape the surface growth from the culture of the testorganism.8Available from Tri-State, Inc., Henderson, KY.9Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the te
34、sting 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 Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.10The boldface numbers given in parentheses r
35、efer to a list of references at theend of the practice.11Historically known as P. funiculosm.G 21 96 (2002)26.4.3 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
36、to liberate the spores from the fruiting bodiesand to break the spore clumps.6.4.4 Filter the shaken suspension through a thin layer ofsterile glass wool in a glass funnel into a sterile flask in orderto remove mycelial fragments.6.4.5 Centrifuge the filtered spore suspension aseptically,and discard
37、 the supernatant liquid. Resuspend the residue in 50mL of sterile water and centrifuge.6.4.6 Wash the spores obtained from each of the fungi inthis manner three times. Dilute the final washed residue withsterile nutrient-salts solution (see Note 3) in such a manner thatthe resultant spore suspension
38、 shall contain 1 000 000 6200 000 spores/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.NOTE 3Nutrient salts solution is identical to the compos
39、ition fornutrient salts agar given in 6.3 except that the agar is omitted.6.4.8 The spore suspension may be prepared fresh each dayor 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
40、 sterilized filter paper, 25 mm (1 in.) square, on hardenednutrient-salts agar in separate Petri dishes. Inoculate these withthe spore suspension by spraying the suspension from asterilized atomizer12so that the entire surface is moistenedwith the spore suspension. Incubate these at 28 to 30C (82 to
41、86F) at a relative humidity not less than 85 % and examinethem after 14 days incubation. There shall be copious growthon all three of the filter paper control specimens. Absence ofsuch growth requires repetition of the test.8. Test Specimens8.1 The simplest specimen may be a 50 by 50-mm (2 by2-in.)
42、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. Completely 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
43、ofgrowth, optical reflection or transmission, or manual evaluationof change in physical properties such as stiffness.8.2 Film-forming 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 strippingaft
44、er cure, or by impregnating (completely covering) filterpaper or ignited glass fabric.8.3 For visual evaluation, three specimens shall be inocu-lated. If the specimen is different on two sides, three specimensof each, face up and face down, shall be tested.NOTE 4In devising a test program intended t
45、o reveal quantitativechanges occurring during and after fungal attack, an adequate number ofspecimens should be evaluated to establish 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 shal
46、l beremoved and tested for each exposure period. It is to be expected thatvalues of physical properties at various stages of fungal 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 Inoculati
47、onPour sufficient nutrient-salts agar intosuitable sterile dishes (see 5.1) to provide a solidified agar layerfrom3to6mm(18 to14 in.) 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 co
48、mposite spore suspension by spraying thesuspension from a sterilized atomizer12with 110 kPa (16 psi)of air pressure so that the entire surface is moistened with thespore suspension.9.2 Incubation Conditions:9.2.1 IncubationCover the inoculated test specimens andincubate at 28 to 30C (82 to 86F) and
49、not less than 85 %relative humidity.NOTE 5Covered dishes containing nutrient agar are considered tohave the desired humidity. Covers on large dishes may be sealed withmasking tape.9.2.2 Incubation DurationThe standard length of the testis 28 days of incubation. The test may be terminated in lessthan 28 days for samples exhibiting a growth rating of two ormore. The final report must detail the actual duration ofincubation.9.3 Observation for Visible EffectsIf the test is for visibleeffects only, remove the specimens from the incubator and ratethe
