1、Designation: G21 13G21 15Standard 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
2、 revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This practice covers determination of th
3、e effect of fungi on the properties of synthetic polymeric materials in the form ofmolded and fabricated articles, tubes, rods, sheets, and film materials. Changes in optical, mechanical, and electrical properties maybe determined by the applicable ASTM methods.1.2 The values stated in SI units are
4、to be regarded as the standard. The inch-pound units given in parentheses are forinformation only.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 this standard to establish appropriate safety and health
5、 practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials atCommercial Power FrequenciesD150 Test Methods for AC Loss C
6、haracteristics and Permittivity (Dielectric Constant) of Solid Electrical InsulationD257 Test Methods for DC Resistance or Conductance of Insulating MaterialsD495 Test Method for High-Voltage, Low-Current, Dry Arc Resistance of Solid Electrical InsulationD618 Practice for Conditioning Plastics for T
7、estingD638 Test Method for Tensile Properties of PlasticsD747 Test Method for Apparent Bending Modulus of Plastics by Means of a Cantilever BeamD785 Test Method for Rockwell Hardness of Plastics and Electrical Insulating MaterialsD882 Test Method for Tensile Properties of Thin Plastic SheetingD1003
8、Test Method for Haze and Luminous Transmittance of Transparent PlasticsD1708 Test Method for Tensile Properties of Plastics by Use of Microtensile SpecimensE96/E96M Test Methods for Water Vapor Transmission of MaterialsE308 Practice for Computing the Colors of Objects by Using the CIE System2.2 TAPP
9、I 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 Cantilever Method4FED STD 191 Method 5206 Stiffness of Cloth Drape and Flex; Cantilever Bending Method41 This practice is under the jurisdicti
10、on of ASTM Committee G03 on Weathering and Durability and is the direct responsibility of Subcommittee G03.04 on BiologicalDeterioration.Current edition approved Nov. 1, 2013June 1, 2015. Published December 2013July 2015. Originally approved in 1961. Last previous edition approved in 20092013 asG21
11、09.G21 13. DOI: 10.1520/G0021-13.10.1520/G0021-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available
12、 from Technical Association of the Pulp and Paper Industry (TAPPI), 15 Technology Parkway South, Norcross, GA 30092, http:/www.tappi.org.4 Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.This do
13、cument 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 users consult prior editions a
14、s appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Summary of Practice3.1 The procedure described in th
15、is practice consists of selection of suitable specimens for determination of pertinent properties,inoculation of the specimens with suitable organisms, exposure of inoculated specimens under conditions favorable to growth,examination and rating for visual growth, and removal of the specimens and obs
16、ervations for testing, either before cleaning or aftercleaning and reconditioning.NOTE 1Since the procedure involves handling and working with fungi, it is recommended that personnel trained in microbiology perform the portionof the procedure involving handling of organisms and inoculated specimens.
17、4. Significance and Use4.1 The synthetic polymer portion of these materials is usually fungus-resistant in that it does not serve as a carbon source forthe growth of fungi. It is generally the other components, such as plasticizers, cellulosics, lubricants, stabilizers, and colorants, thatare respon
18、sible for fungus attack on plastic materials. To assess materials other than plastics, use of this test method should beagreed upon by all parties involved. It is important to establish the resistance to microbial attack under conditions favorable forsuch attack, namely, a temperature of 2 to 38C (3
19、5 to 100F) and a relative humidity of 60 to 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, and lubricants, resulting in increased modulus (stiffness), changes inweight,
20、dimensions, and other physical properties, and deterioration of electrical properties such as insulation resistance, dielectricconstant, power factor, and dielectric strength.4.3 Often the changes in electrical properties are due principally to surface growth and its associated moisture and to pH ch
21、angescaused by excreted metabolic products. Other effects include preferential growth caused by nonuniform dispersion of plasticizers,lubricants, and other processing additives. Attack on these materials often leaves ionized conducting paths. Pronounced physicalchanges are observed on products in fi
22、lm form or as coatings, where the ratio of surface to volume is high, and where nutrientmaterials such as plasticizers and lubricants continue to diffuse to the surface as they are utilized by the organisms.4.4 Since attack by organisms involves a large element of chance due to local accelerations a
23、nd inhibitions, the order ofreproducibility may be rather low. To ensure that estimates of behavior are not too optimistic, the greatest observed degree ofdeterioration should be reported.4.5 Conditioning of the specimens, such as exposure to leaching, weathering, heat treatment, etc., may have sign
24、ificant effectson the resistance to fungi. Determination of these effects is not covered in this practice.5. Apparatus5.1 GlasswareGlass or plastic vessels are suitable for holding specimens when laid flat. Depending on the size of thespecimens, the following are suggested:5.1.1 For specimens up to
25、75 mm (3 in.) in diameter, 100 by 100 mm (414 by 414 in.) plastic boxes5 or 150-mm (6-in.) coveredPetri dishes, and5.1.2 For 75 mm (3 in.) and larger specimens, such as tensile and stiffness strips, large Petri dishes, trays of borosilicate glass,or baking dishes up to 400 by 500 mm (16 by 20 in.) i
26、n size, covered with squares of window glass.5.2 IncubatorIncubating equipment for all test methods shall maintain a temperature of 28 to 30C (82.4 to 86F) and arelative humidity not less than 85 %. Automatic recording of wet and dry-bulb temperature is recommended.6. Reagents and Materials6.1 Purit
27、y of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch specification are available.6 Other grades may be used,
28、 provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean distilled water or water ofequal or higher purity.6.3
29、Nutrient-Salts AgarPrepare this medium by dissolving in 1 L of water the designated amounts of the following reagents:5 Available from Tri-State, Inc., Henderson, KY.6 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testi
30、ng of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.G21 152Potassium dihydrogen orthophosphate (KH
31、2PO4) 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 (MnSO4H2O) 0.001 gAgar 15.0 gPotassium monohydrogen orthophosphate (K2HPO4) 0.7 gDipotassium monohydrogen or
32、thophosphate (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 the addition of0.01 N NaOH solution so that after sterilization the pH is between 6.0 and 6.5.6.3.2 Prepare sufficient medium for the required tests.6.3.3 Nutrient Salt
33、s BrothPrepare using the formula in 6.3, 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 interest for certain final assemblies or compone
34、nts, such other pure cultures oforganisms may be used if agreed upon by the purchaser and the manufacturer of the plastic. Reference (1)7 illustrates such a choice.7 The boldface numbers given in parentheses refer to a list of references at the end of the practice.G21 1536.4.1 Use the following test
35、 fungi in preparing the cultures:Fungi ATCC No.A MYCO No.BAspergillus niger 9642 386Penicillium pinophilumC 11797 391Chaetomium globosum 6205 459Trichoderma virensD 9645 365Aureobasidium pullulans 15233 279cFungi ATCC No.AAspergillus brasiliensisB 9642Penicillium funiculosumC 11797Chaetomium globosu
36、m 6205Trichoderma virensD 9645Aureobasidium pullulans 15233AAvailable from American Type Culture Collection, 12301 Parklawn Drive, Rockville, MD 20852.BAvailable from MycologicalHistorically known as Services, P.O. A. niger.Box 1056, Crawfordsville, IN 47933.CHistorically known as P. funiculosm.pino
37、philum.DHistorically known as Gliocladium virens.6.4.1.1 Maintain cultures of these fungi separately on an appropriate medium such as potato dextrose agar. The stock culturesmay be kept for not more than four months at approximately 3 to 10C (37 to 50F). Use subcultures incubated at 28 to 30C (82to
38、86F) for 7 to 20 days in preparing the spore suspension.6.4.1.2 Prepare a spore suspension of each of the five fungi by pouring into one subculture of each fungus a sterile 10-mLportion of water or of a sterile solution containing 0.05 g/L of a nontoxic wetting agent such as sodium dioctyl sulfosucc
39、inate. Usea sterile platinum platinum, plastic, or nichrome inoculating wire to gently 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 flask or tube containing 45 mL of sterilewater with wetting agent a
40、nd 10 to 15 solid glass beads, 5 mm in diameter. Shake beads. Cap and shake the flask vigorously toliberate the spores from the fruiting bodies and to break the spore clumps.6.4.3 Alternatively, the spore charge can be poured into a sterile glass tissue grinder and gently ground to break up the spor
41、eclumps and liberate the spores from the fruiting bodies.6.4.4 Filter the shaken or ground suspension through a thin layer of sterile glass wool in a glass funnel into a sterile flask inorder to remove mycelial fragments.6.4.5 Centrifuge the filtered spore suspension aseptically, and discard the sup
42、ernatant liquid. Resuspend the residue in an aliquotof sterile water and centrifuge.6.4.6 If large mycelia fragments or clumps of agar were dislodged during the harvesting, wash the spores in this manner threetimes to remove possible nutrient carryover from the original cultures. Dilute the final wa
43、shed residue with sterile nutrient-saltssolution (see 6.3.3) in such a manner that the resultant spore suspension shall contain 1 000 000 6 200 000 spores/mL asdetermined with a counting chamber.6.4.7 Repeat this operation for each organism used in the test and blend equal volumes of the resultant s
44、pore suspension toobtain the final mixed spore suspension.6.4.8 The mixed spore suspension may be prepared fresh each day or may be held in the refrigerator at 3 to 10C (37 to 50F)for not more than four days. The individual spore suspensions may be held in the refrigerator at 3 to 10C (37 to 50F) fo
45、r notmore than fourteen days.7. Viability Control7.1 With each daily group of tests place each of three pieces of sterilized filter paper, 25 mm (1 in.) square, on hardenednutrient-salts agar in separate Petri dishes. Inoculate these these, along with the test items, with the spore suspension by spr
46、ayingthe suspension from a sterilized atomizer8 so that the entire surface is moistened with the spore suspension. Incubate these at 28to 30C (82 to 86F) at a relative humidity not less than 85 % and examine them after 14 days incubation. There shall be copiousgrowth on all three of the filter paper
47、 control specimens. Absence of such growth requires repetition of the test.8. Test Specimens8.1 The simplest specimen may be a 50 by 50-mm (2 by 2-in.) piece, a 50-mm (2-in.) diameter piece, or a piece (rod or tubing)at least 76 mm (3 in.) long cut from the material to be tested. Completely fabricat
48、ed parts or sections cut from fabricated parts maybe used as test specimens. On such specimens, observation of effect is limited to appearance, density of growth, optical reflectionor transmission, or manual evaluation of change in physical properties such as stiffness.8 DeVilbiss No. 163 atomizer o
49、r equivalent has been found satisfactory for this purpose.G21 1548.2 Film-forming materials such as coatings may be tested in the form of films at least 50 by 25 mm (2 by 1 in.) in size. Suchfilms may be prepared by casting on glass and stripping after cure, or by impregnating (completely covering) filter paper or ignitedglass fabric.8.3 For visual evaluation, three specimens shall be inoculated. If the specimen is different on two sides, three specimens of each,face up and face down, shall be tested.NOTE 3In devising a test program intende
