ASTM G21-96(2002)
(Specification)Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi
Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi
SIGNIFICANCE AND USE
The synthetic polymer portion of these materials is usually fungus-resistant in that it does not serve as a carbon source for the growth of fungi. It is generally the other components, such as plasticizers, cellulosics, lubricants, stabilizers, and colorants, that are responsible for fungus attack on plastic materials. It is important to establish the resistance to microbial attack under conditions favorable for such attack, namely, a temperature of 2 to 38°C (35 to 100°F) and a relative humidity of 60 to 100 %.
The effects to be expected are as follows:
4.2.1 Surface attack, discoloration, loss of transmission (optical), and
4.2.2 Removal of susceptible plasticizers, modifiers, and lubricants, resulting in increased modulus (stiffness), changes in weight, dimensions, and other physical properties, and deterioration of electrical properties such as insulation resistance, dielectric constant, power factor, and dielectric strength.
Often the changes in electrical properties are due principally to surface growth and its associated moisture and to pH changes caused by excreted metabolic products. Other effects include preferential growths caused by nonuniform dispersion of plasticizers, lubricants, and other processing additives. Attack on these materials often leaves ionized conducting paths. Pronounced physical changes are observed on products in film form or as coatings, where the ratio of surface to volume is high, and where nutrient materials such as plasticizers and lubricants continue to diffuse to the surface as they are utilized by the organisms.
Since attack by organisms involves a large element of chance due to local accelerations and inhibitions, the order of reproducibility may be rather low. To ensure that estimates of behavior are not too optimistic, the greatest observed degree of deterioration should be reported.
Conditioning of the specimens, such as exposure to leaching, weathering, heat treatment, etc., may have significant effects on the...
SCOPE
1.1 This practice covers determination of the effect of fungi on the properties of synthetic polymeric materials in the form of molded and fabricated articles, tubes, rods, sheets, and film materials. Changes in optical, mechanical, and electrical properties may be determined by the applicable ASTM methods.
1.2 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:G21–96 (Reapproved 2002)
Standard Practice for
Determining Resistance of Synthetic Polymeric Materials to
Fungi
ThisstandardisissuedunderthefixeddesignationG21;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber 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 agencies of the Department of Defense.
1. Scope D785 Test Method for Rockwell Hardness of Plastics and
Electrical Insulating Materials
1.1 This practice covers determination of the effect of fungi
D1003 Test Method for Haze and Luminous Transmittance
on the properties of synthetic polymeric materials in the form
of Transparent Plastics
of molded and fabricated articles, tubes, rods, sheets, and film
D882 Test Method for Tensile Properties of Thin Plastic
materials. Changes in optical, mechanical, and electrical prop-
Sheeting
erties may be determined by the applicable ASTM methods.
D1708 Test Method for Tensile Properties of Plastics by
1.2 The values stated in SI units are to be regarded as the
Use of Microtensile Specimens
standard. The inch-pound units given in parentheses are for
E96/E96M Test Methods for Water Vapor Transmission of
information only.
Materials
1.3 This standard does not purport to address all of the
E308 Practice for Computing the Colors of Objects by
safety concerns, if any, associated with its use. It is the
Using the CIE System
responsibility of the user of this standard to establish appro-
2.2 TAPPI Standard:
priate safety and health practices and determine the applica-
Test Method T 451-CM-484 Flexural Properties of Paper
bility of regulatory limitations prior to use.
2.3 Federal Standards:
2. Referenced Documents FED STD 191 Method 5204 Stiffness of Cloth, Directional;
Self Weighted Cantilever Method
2.1 ASTM Standards:
FED STD 191 Method 5206 Stiffness of Cloth Drape and
D149 Test Method for Dielectric Breakdown Voltage and
Flex; Cantilever Bending Method
Dielectric Strength of Solid Electrical Insulating Materials
at Commercial Power Frequencies
3. Summary of Practice
D150 Test Methods for AC Loss Characteristics and Per-
3.1 The procedure described in this practice consists of
mittivity (Dielectric Constant) of Solid Electrical Insula-
selection of suitable specimens for determination of pertinent
tion
properties, inoculation of the specimens with suitable organ-
D257 Test Methods for DC Resistance or Conductance of
isms, exposure of inoculated specimens under conditions
Insulating Materials
favorable to growth, examination and rating for visual growth,
D495 Test Method for High-Voltage, Low-Current, DryArc
and removal of the specimens and observations for testing,
Resistance of Solid Electrical Insulation
either before cleaning or after cleaning and reconditioning.
D618 Practice for Conditioning Plastics for Testing
D638 Test Method for Tensile Properties of Plastics
NOTE 1—Since the procedure involves handling and working with
D747 Test Method for Apparent Bending Modulus of Plas-
fungi, it is recommended that personnel trained in microbiology perform
the portion of the procedure involving handling of organisms and
tics by Means of a Cantilever Beam
inoculated specimens.
4. Significance and Use
This practice is under the jurisdiction ofASTM Committee G03 onWeathering
and Durability and is the direct responsibility of Subcommittee G03.04 on
4.1 The synthetic polymer portion of these materials is
Biological Deterioration.
usually fungus-resistant in that it does not serve as a carbon
Current edition approved Jan. 10, 2002. Published May 2002. Originally
published as D1924 – 61. Last previous edition D1924 – 90. Redesignated G21 in
1970 (Reapproved 1990). DOI: 10.1520/G0021-96R02.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from TechnicalAssociation of the Pulp and Paper Industry, Technol-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM ogy Park/Atlanta, P.O. Box 105113, Atlanta, GA 30348.
Standards volume information, refer to the standard’s Document Summary page on AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700
the ASTM website. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G21–96 (2002)
source for the growth of fungi. It is generally the other tee onAnalytical Reagents of theAmerican Chemical Society,
components, such as plasticizers, cellulosics, lubricants, stabi- where such specification are available. Other grades may be
lizers, and colorants, that are responsible for fungus attack on used, provided it is first ascertained that the reagent is of
plastic materials. It is important to establish the resistance to sufficiently high purity to permit its use without lessening the
microbial attack under conditions favorable for such attack, accuracy of the determination.
namely, a temperature of 2 to 38°C (35 to 100°F) and a relative
6.2 Purity of Water—Unless otherwise indicated, references
humidity of 60 to 100 %.
to water shall be understood to mean distilled water or water of
4.2 The effects to be expected are as follows:
equal purity.
4.2.1 Surface attack, discoloration, loss of transmission
6.3 Nutrient-Salts Agar—Prepare this medium by dissolv-
(optical), and
ing in 1 L of water the designated amounts of the following
4.2.2 Removal of susceptible plasticizers, modifiers, and
reagents:
lubricants, resulting in increased modulus (stiffness), changes
Potassium dihydrogen orthophosphate (KH PO ) 0.7 g
2 4
in weight, dimensions, and other physical properties, and ·7H O) 0.7 g
Magnesium sulfate (MgSO
4 2
Ammonium nitrate (NH NO ) 1.0 g
4 3
deterioration of electrical properties such as insulation resis-
Sodium chloride (NaCl) 0.005 g
tance, dielectric constant, power factor, and dielectric strength.
Ferrous sulfate (FeSO ·7H O) 0.002 g
4 2
4.3 Often the changes in electrical properties are due prin-
Zinc sulfate (ZnSO ·7H O) 0.002 g
4 2
Manganous sulfate (MnSO ·H O) 0.001 g
4 2
cipally to surface growth and its associated moisture and to pH
Agar 15.0 g
changes caused by excreted metabolic products. Other effects
Potassium monohydrogen orthophosphate (K HPO ) 0.7 g
2 4
include preferential growths caused by nonuniform dispersion
6.3.1 Sterilize the test medium by autoclaving at 121°C
of plasticizers, lubricants, and other processing additives.
(250°F) for 20 min. Adjust the pH of the medium by the
Attack on these materials often leaves ionized conducting
addition of 0.01 N NaOH solution so that after sterilization the
paths. Pronounced physical changes are observed on products
pH is between 6.0 and 6.5.
in film form or as coatings, where the ratio of surface to
6.3.2 Prepare sufficient medium for the required tests.
volume is high, and where nutrient materials such as plasticiz-
6.4 Mixed Fungus Spore Suspension:
ers and lubricants continue to diffuse to the surface as they are
utilized by the organisms.
NOTE 2—Since a number of other organisms may be of specific interest
4.4 Since attack by organisms involves a large element of
for certain final assemblies or components, such other pure cultures of
chance due to local accelerations and inhibitions, the order of
organisms may be used if agreed upon by the purchaser and the
reproducibility may be rather low. To ensure that estimates of
manufacturer of the plastic. Reference (1) illustrates such a choice.
behavior are not too optimistic, the greatest observed degree of
6.4.1 Use the following test fungi in preparing the cultures:
deterioration should be reported.
A B
Fungi ATCC No. MYCO No.
4.5 Conditioning of the specimens, such as exposure to
leaching, weathering, heat treatment, etc., may have significant
Aspergillus niger 9642 386
C
Penicillium pinophilum 11797 391
effectsontheresistancetofungi.Determinationoftheseeffects
Chaetomium globosum 6205 459
is not covered in this practice.
Gliocladium virens 9645 365
Aureobasidium pullulans 15233 279c
5. Apparatus
A
Available from American Type Culture Collection, 12301 Parklawn Drive,
5.1 Glassware—Glass or plastic vessels are suitable for
Rockville, MD 20852.
B
AvailablefromMycologicalServices,P.O.Box1056,Crawfordsville,IN47933.
holding specimens when laid flat. Depending on the size of the
C
Historically known as P. funiculosm.
specimens, the following are suggested:
6.4.1.1 Maintain cultures of these fungi separately on an
5.1.1 For specimens up to 75 mm (3 in.) in diameter, 4 ⁄4 by
appropriate medium such as potato dextrose agar. The stock
4 ⁄4 in. (100 by 100 mm) plastic boxes or 150-mm (6-in.)
cultures may be kept for not more than four months at
covered Petri dishes, and
approximately 3 to 10°C (37 to 50°F). Use subcultures
5.1.2 For 75 mm (3 in.) and larger specimens, such as
incubated at 28 to 30°C (82 to 86°F) for 7 to 20 days in
tensile and stiffness strips, large Petri dishes, trays of borosili-
preparing the spore suspension.
categlass,orbakingdishesupto400by500mm(16by20in.)
6.4.2 Prepareasporesuspensionofeachofthefivefungiby
in size, covered with squares of window glass.
5.2 Incubator—Incubating equipment for all test methods pouring into one subculture of each fungus a sterile 10-mL
portion of water or of a sterile solution containing 0.05 g/L of
shall maintain a temperature of 28 to 30°C (82.4 to 86°F) and
a relative humidity not less than 85 %.Automatic recording of
wetand dry-bulb temperature is recommended.
Reagent Chemicals, American Chemical Society Specifications , American
6. Reagents and Materials
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
6.1 Purity of Reagents—Reagent grade chemicals shall be
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
used in all tests. Unless otherwise indicated, it is intended that
and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
all reagents shall conform to the specifications of the Commit-
MD.
The boldface numbers given in parentheses refer to a list of references at the
end of the practice.
5 8
Available from Tri-State, Inc., Henderson, KY. Historically known as P. funiculosm.
...
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