ASTM D2765-11
(Test Method)Standard Test Methods for Determination of Gel Content and Swell Ratio of Crosslinked Ethylene Plastics
Standard Test Methods for Determination of Gel Content and Swell Ratio of Crosslinked Ethylene Plastics
SIGNIFICANCE AND USE
Many important properties of crosslinked ethylene plastics vary with the gel content. Hence, determination of the gel content provides a means of both controlling the process and rating the quality of finished products.
Extraction tests permit verification of the proper gel content of any given crosslinked ethylene plastic and they also permit comparison between different crosslinked ethylene plastics, including those containing fillers, provided that, for the latter, the following conditions are met:
The filler is not soluble in either decahydronaphthalene or xylenes at the extraction temperature.
The amount of filler present in the compound either is known or will be determined by other means.
Sufficient crosslinking has been achieved to prevent migration of filler during the extraction. Usually it has been found that, at extraction levels up to 50 %, the extractant remains clear and free of filler.
A suitable antioxidant is added to the extractant to inhibit possible oxidative degradation at the extraction temperatures.
Before proceeding with this test method, reference shall be made to the specification of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or a combination thereof, covered in the materials specification shall take precedence over those mentioned in this test method. If there are no material specifications, then the default conditions apply.
SCOPE
1.1 The gel content (insoluble fraction) produced in ethylene plastics by crosslinking is determined by extracting with solvents such as decahydronaphthalene or xylenes. The methods described herein are applicable to crosslinked ethylene plastics of all densities, including those containing fillers, and all provide corrections for the inert fillers present in some of those compounds.
1.2 Test Method A, which permits most complete extraction in least time, is to be used for referee tests, but two alternative nonreferee Test Methods B and C are also described. Test Method B differs from the referee test method only in sample preparation; that is, it requires use of shavings taken at selected points in cable insulation, for example, rather than the ground sample required by the referee test method. Because the shaved particles are larger, less total surface per sample is exposed to the extractant, so this test method ordinarily yields extraction values about 1 to 2 % lower than the referee method. Test Method C requires that a specimen in one piece be extracted in xylenes at a constant temperature of 110°C. At this temperature and with a one-piece specimen, even less extraction occurs (from 3 to 9 % less than the referee test method), this method permits swell ratio (a measure of the degree of crosslinking in the gel phase) be determined.
1.3 Extraction tests are made on articles of any shape. They have been particularly useful for electrical insulations since specimens may be selected from those portions of the insulation most susceptible to insufficient crosslinking.
1.4 The values stated in SI units are to be regarded as standard. The inch-pound units in brackets are for information only.
Note 1—Method B of this test method is equivalent to ISO 10147.
1.5 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. Specific precautionary statements are given in Sections 6, 10, and 25.
15.1 This modification of the referee test method was developed particularly for wire and cable insulations and differs from the referee test method only in specimen preparation.
15.2 In using this alternative test method, it is recognized that the values obtained at times, are lower than those obtained by referee Test Method A for the reason give...
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Designation: D2765 − 11
StandardTest Methods for
Determination of Gel Content and Swell Ratio of
1
Crosslinked Ethylene Plastics
This standard is issued under the fixed designation D2765; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 The gel content (insoluble fraction) produced in ethyl-
bility of regulatory limitations prior to use. Specific precau-
ene plastics by crosslinking is determined by extracting with
tionary statements are given in Sections 6, 10, and 25.
solvents such as decahydronaphthalene or xylenes. The meth-
ods described herein are applicable to crosslinked ethylene
2. Referenced Documents
plastics of all densities, including those containing fillers, and
2
2.1 ASTM Standards:
all provide corrections for the inert fillers present in some of
D297Test Methods for Rubber Products—ChemicalAnaly-
those compounds.
sis
1.2 TestMethodA,whichpermitsmostcompleteextraction
D618Practice for Conditioning Plastics for Testing
in least time, is to be used for referee tests, but two alternative
D883Terminology Relating to Plastics
nonreferee Test Methods B and C are also described. Test
D1603Test Method for Carbon Black Content in Olefin
Method B differs from the referee test method only in sample
Plastics
preparation;thatis,itrequiresuseofshavingstakenatselected
D1998SpecificationforPolyethyleneUprightStorageTanks
points in cable insulation, for example, rather than the ground
D3351Test Method for Gel Count of Plastic Film (With-
samplerequiredbytherefereetestmethod.Becausetheshaved
3
drawn 2000)
particles are larger, less total surface per sample is exposed to
E691Practice for Conducting an Interlaboratory Study to
the extractant, so this test method ordinarily yields extraction
Determine the Precision of a Test Method
values about 1 to 2% lower than the referee method. Test
2.2 ISO Standard:
MethodCrequiresthataspecimeninonepiecebeextractedin
ISO10147 Pipes and Fittings Made of Crosslinked Poly-
xylenesataconstanttemperatureof110°C.Atthistemperature
ethylene (Pe-X)—Estimation of the Degree of Crosslink-
and with a one-piece specimen, even less extraction occurs
ing by Determination of the Gel Content
(from 3 to 9% less than the referee test method), this method
permits swell ratio (a measure of the degree of crosslinking in
3. Terminology
the gel phase) be determined.
3.1 Definitions of Terms Specific to This Standard:
1.3 Extraction tests are made on articles of any shape.They
3.1.1 gel content—the percentage by mass of polymer
have been particularly useful for electrical insulations since
insoluble in a specified solvent after extraction under the
specimens may be selected from those portions of the insula-
specified conditions.
tion most susceptible to insufficient crosslinking.
3.1.2 soluble—capable of being loosened or dissolved, sus-
1.4 The values stated in SI units are to be regarded as
ceptible of being dissolved in or as if in a fluid. (SeeWebster’s
standard. The inch-pound units in brackets are for information
Ninth New Collegiate Dictionary, 1988.)
only.
3.1.3 swell ratio—the ratio of the gel volume in the swollen
NOTE 1—Method B of this test method is equivalent to ISO10147.
state to its volume in the unswollen state.
1.5 This standard does not purport to address all of the
3.2 Terms as shown in Terminology D883 are applicable to
safety concerns, if any, associated with its use. It is the
this test method.
1 2
These test methods are under the jurisdiction of ASTM Committee D20 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
PlasticsandarethedirectresponsibilityofSubcommitteeD20.15onThermoplastic contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Materials. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedSept.1,2011.PublishedSeptember1,2011.Originally the ASTM website.
3
approved in 1968. Last previous edition approved in 2006 as D2765–01(2006). The last approved version of this historical standard is referenced on
DOI: 10.1520/D2765-11. www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D2765 − 11
4. Summary of Test Methods TEST METHOD A (REFEREE TEST METHOD)
4.1 Specimens of the crosslinked ethylene plastic are
8. Apparatus
weighed and then immersed
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D2765–01 (Reapproved 2006) Designation:D2765–11
Standard Test Methods for
Determination of Gel Content and Swell Ratio of
1
Crosslinked Ethylene Plastics
This standard is issued under the fixed designation D2765; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 The gel content (insoluble fraction) produced in ethylene plastics by crosslinking can be is determined by extracting with
solvents such as decahydronaphthalene or xylenes. Such extraction test The methods are described herein. Theyherein are
applicabletocrosslinkedethyleneplasticsofalldensities,includingthosecontainingfillers,andallprovidecorrectionsfortheinert
fillers present in some of those compounds.
1.2 Test Method A, which permits most complete extraction in least time, is to be used for referee tests, but two alternative
nonreferee Test Methods B and C are also described. The first of these Test Method B differs from the referee test method only
in sample preparation; that is, it requires use of shavings taken at selected points in cable insulation, for example, rather than the
groundsamplerequiredbytherefereetestmethod.Becausetheshavedparticlesarelarger,lesstotalsurfacepersampleisexposed
to the extractant, so this test method ordinarily yields extraction values about 1 to 2% lower than the referee method.The second
of the alternative test methods Test Method C requires that a specimen in one piece be extracted in xylenes at a constant
temperature of 110°C.At this temperature and with a one-piece specimen, even less extraction occurs (from 3 to 9% less than the
referee test method) but method), this method permits swell ratio (a measure of the degree of crosslinking in the gel phase) can
be determined.
1.3 Extraction tests can beare made on articles of any shape. They have been particularly useful for electrical insulations since
specimens may be selected from those portions of the insulation most susceptible to insufficient crosslinking.
1.4 The values stated in SI units are to be regarded as standard. The inch-pound units in brackets are for information only.
NOTE1—ISO 10147 is similar to this test, but is not equivalent. 1—Method B of this test method is equivalent to ISO10147.
1.5 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. Specific precautionary statements are given in Sections 6, 10, and 25.
2. Referenced Documents
2
2.1 ASTM Standards:
D297 Test Methods for Rubber ProductsChemical Analysis
D618 Practice for Conditioning Plastics for Testing
D883 Terminology Relating to Plastics
D1603 Test Method for Carbon Black Content in Olefin Plastics
D1998 Specification for Polyethylene Upright Storage Tanks
D3351 Test Method for Gel Count of Plastic Film
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 ISO Standard:
ISO10147 Pipes and Fittings Made of Crosslinked Polyethylene (Pe-X)—Estimation of the Degree of Crosslinking by
Determination of the Gel Content
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
1
ThesetestmethodsareunderthejurisdictionofASTMCommitteeD20onPlasticsandarethedirectresponsibilityofSubcommitteeD20.15onThermoplasticMaterials.
Current edition approved April 1, 2006. Published April 2006. Originally approved in 1968. Last previous edition approved in 2001 as D2765–01. DOI:
10.1520/D2765-01R06.
Current edition approved Sept. 1, 2011. Published September 1, 2011. Originally approved in 1968. Last previous edition approved in 2006 as D2765–01(2006). DOI:
10.1520/D2765-11.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book ofASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
D2765–11
3.1.1 gel content—the percentage by mass of polymer insoluble in a specified solvent after
...
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