ASTM_D_7567_-_09.pdf

Designation:D756709StandardTest Method forDetermining Gel Content in Crosslinked Ethylene PlasticsUsing Pressurized Liquid Extraction1This standard is issued under the fixed designation D7567;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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 The gel content of crosslinked ethylene plastics isdetermined by solvent extraction with xylene or toluene.Thistest method is applicable to ethylene plastics of all densities,including those containing fillers;provided the fillers areinsoluble in the extraction solvent(s).1.2 This test method uses pressurized liquid extraction(PLE)to increase the speed and reduce the amount of solventrequired for solvent extraction.The results of this method aresimilar to Test Method D2765.1.3 Extraction tests shall be performed on samples of anyshape(see 7.2).Specimens shall be selected from thoseportions of the article most susceptible to insufficient cross-linking or selected from portions representative of the entirearticle.This test method has been developed for production andquality control of crosslinked polyethylene pipe but may beapplicable to other products such as multilayer materials andfibers.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 This method makes use of minimal reagents and allowsfor solvent recovery and re-use.Due to the use of minimalreagents,health and safety concerns are minimized in compari-son to other methods.1.6 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.Specific precaution-ary statements are given in Section 10.NOTE1There is no known ISO equivalent to this test method.Thistest method is similar to Test Method D2765.2.Referenced Documents2.1 ASTM Standards:2D297 Test Methods for Rubber ProductsChemical Analy-sisD618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD1603 Test Method for Carbon Black Content in OlefinPlasticsD2765 Test Methods for Determination of Gel Content andSwell Ratio of Crosslinked Ethylene PlasticsD3351 Test Method for Gel Count of Plastic Film(With-drawn 2000)3E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Description of Terms Specific to This Standard:3.1.1 gel contentthe percentage by mass of polymerinsoluble in a specified polymer after extraction under thespecified conditions.3.1.2 solublecapable of being loosened or dissolved,sus-ceptible of being dissolved in or as if in a fluid.(See WebstersNinth New Collegiate Dictionary,1988.)4.Summary of Test Method4.1 Specimens of the crosslinked ethylene plastic areweighed,placed in an extraction cell,and extracted underpressure at a specified temperature for a specified time.Afterextraction,the specimens are removed,dried,and reweighed.The amount of material extracted is calculated.5.Significance and Use5.1 Many important properties of crosslinked ethylene plas-tics vary with the gel content.Hence,determination of the gel1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods andis the direct responsibility of Task Group D20.70.01 on Physical Properties.Current edition approved Nov.15,2009.Published December 2009.DOI:10.1520/D756709.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesNOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)for the latest information1content provides a means of both controlling the process andrating the quality of finished products.5.2 Extraction tests permit verification of the desired gelcontent of any given crosslinked ethylene plastic and they alsopermit comparison between different crosslinked ethyleneplastics,including those containing fillers,provided that,forthe latter,the following conditions are met:The filler is notsoluble in xylene or toluene at the extraction temperature andthe amount of filler present in the compound is known or canbe determined.5.3 Sufficient crosslinking has been achieved to preventmigration of filler during the extraction.Usual