ASTM_D_5247_-_92.pdf

Designation:D 5247 92Standard Test Method forDetermining the Aerobic Biodegradability of DegradablePlastics by Specific Microorganisms1This standard is issued under the fixed designation D 5247;the number immediately following the designation 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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method describes the procedures required tocarry out a pure-culture study for evaluating the biodegradationof degradable plastics in submerged culture under aerobicconditions.Degradation will be evaluated by weight loss,tensile strength loss,percent-elongation loss and changes inmolecular-weight distribution.1.2 This standard does not purport to address all of thesafety problems,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.Referenced Documents2.1 ASTM Standards:D 638 Test Method for Tensile Properties of Plastics2D 882 Test Methods for Tensile Properties of Thin PlasticSheeting2D 3536 Test Method for Molecular Weight Averages andMolecular Weight Distribution of Polystyrene by LiquidExclusionChromatography(GelPermeationChromatographyGPC)3G 22 Practice for Determining Resistance of Plastics toBacteria43.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 degradable plastica plastic designed to undergo asignificant change in its chemical structure under specificenvironmental conditions resulting in a loss of some propertiesthat may vary as measured by standard test methods appropri-ate to the plastic and the application in a period of time thatdetermines its classification.3.1.2 residual plasticthe remaining plastic material in theculture medium after incubation with shaking.3.1.3 uninoculated controla plastic that is chemicallydisinfected and incubated with shaking in the same manner astest samples but without exposure to microorganisms.3.1.4 zero controla plastic without disinfection or culturalincubation;the starting material.4.Summary of Test Method4.1 The test method described herein follows the methoddeveloped by Lee et al.5and consists of the following steps:4.1.1 Cut degradable plastic samples into appropriatelengths suitable for tensile strength determinations as specifiedin Test Methods D 882 and a suitable size for a 250-mLErlenmeyer shake-flask.4.1.2 Plastic strips are chemically disinfected,asepticallydried,and initial weights determined.4.1.3 Disinfected plastic strips are aseptically added to theappropriate growth medium,incubated with shaking for 24 h(125 r/min;orbital shaker)at the appropriate temperature forthe specific microorganism being used.If not contaminated(contaminated medium becomes cloudy)the medium is theninoculated with a pure culture.4.1.4 Inoculated and uninoculated-control flasks are incu-bated with shaking for specified period of time.Each film isevaluated with a minimum of four replicates with and withouteach microorganism.4.1.5 Residual plastic strips are washed in 70%ethanol for30 min and dried.4.1.6 Biodegradation is determined by weight loss,tensile-strength loss,percent-elongation loss,and average-molecular-weight distribution changes.4.1.7 Significant differences between the inoculated flaskand its corresponding uninoculated-control film are determinedby performing an analysis of variance(p 0.05).5.Significance and Use5.1 Several states in the United States and many Europeancountries have required the use of degradable plastics indisposable products.As a result,several regulatory agencies1This test method is under the jurisdiction ofASTM Committee D-20 on Plasticsand is the direct responsibility of Subcommittee D20.96 on EnvironmentallyDegradable Plastics.Current edition approved May 15,1992.Published July 1992.2Annual Book of ASTM Standards,Vol 08.01.3Annual Book of ASTM Standards,Vol 08.02.4Annual Book of ASTM Standards,Vol 08.03.5Lee,B.,Pometto III,A.L.,Fratzke,A.,and Bailey Jr.,T.B.,“Biodegradationof Degradable Plastic Polyethylene by Phanerochaete and Streptomyces,”AppliedEnvironmental Microbiology 57,1991,pp.678685.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)for the latest informationhave the need to evaluate degradable products for compliancewith state and local regulations.In todays market there arethree main actions by which degradable plastics are designed todegrade:(1)biological,(2)chemical,or(3)photo degradation,or combination thereof.The final degradation of all degradableplastic materials,whether they be initially degraded by photo-or chemical-degradation,will be by microorganisms.Thi