ASTM D2765-01
(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
SCOPE
1.1 The gel content (insoluble fraction) produced in ethylene plastics by crosslinking can be determined by extracting with solvents such as decahydronaphthalene or xylene. Such extraction test methods are described herein. They 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. The first of these 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. The second of the alternative test methods requires that a specimen in one piece be extracted in xylene 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 swell ratio (a measure of the degree of crosslinking in the gel phase) can be determined.
1.3 Extraction tests can be 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 the standard. The inch-pound units in parentheses are for information only. Note 1-ISO 10147 is similar to this test, but is not equivalent.
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.
General Information
Relations
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:D2765–01
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope* bility of regulatory limitations prior to use. Specific precau-
tionary statements are given in Sections 6, 10, and 25.
1.1 The gel content (insoluble fraction) produced in ethyl-
ene plastics by crosslinking can be determined by extracting
2. Referenced Documents
with solvents such as decahydronaphthalene or xylenes. Such
2
2.1 ASTM Standards:
extraction test methods are described herein. They are appli-
D 297 Test Methods for Rubber Products—Chemical
cabletocrosslinkedethyleneplasticsofalldensities,including
Analysis
thosecontainingfillers,andallprovidecorrectionsfortheinert
D618 Practice for Conditioning Plastics and Electrical
fillers present in some of those compounds.
Insulating Materials for Testing
1.2 TestMethodA,whichpermitsmostcompleteextraction
D883 Terminology Relating to Plastics
in least time, is to be used for referee tests, but two alternative
D1603 Test Method for Carbon Black in Olefin Plastics
nonreferee Test Methods B and C are also described. The first
D 1998 Specification for Polyethylene Upright Storage
of these differs from the referee test method only in sample
Tank
preparation;thatis,itrequiresuseofshavingstakenatselected
D3351 Test Method for Gel Count of Plastic Film
points in cable insulation, for example, rather than the ground
E691 Practice for Conducting an Interlaboratory Study to
samplerequiredbytherefereetestmethod.Becausetheshaved
Determine the Precision of a Test Method
particles are larger, less total surface per sample is exposed to
the extractant, so this test method ordinarily yields extraction
3. Terminology
values about 1 to 2% lower than the referee method. The
3.1 Definitions of Terms Specific to This Standard:
second of the alternative test methods requires that a specimen
3.1.1 gel content—the percentage by mass of polymer
in one piece be extracted in xylenes at a constant temperature
insoluble in a specified solvent after extraction under the
of 110°C. At this temperature and with a one-piece specimen,
specified conditions.
even less extraction occurs (from 3 to 9% less than the referee
3.1.2 soluble—capable of being loosened or dissolved, sus-
test method) but swell ratio (a measure of the degree of
ceptible of being dissolved in or as if in a fluid. (SeeWebster’s
crosslinking in the gel phase) can be determined.
Ninth New Collegiate Dictionary, 1988.)
1.3 Extraction tests can be made on articles of any shape.
3.1.3 swell ratio—theratioofthegelvolumeintheswollen
They have been particularly useful for electrical insulations
state to its volume in the unswollen state.
since specimens may be selected from those portions of the
3.2 Terms as shown inTerminology D883 are applicable to
insulation most susceptible to insufficient crosslinking.
this test method.
1.4 The values stated in SI units are to be regarded as the
standard.The inch-pound units in parentheses are for informa-
4. Summary of Test Methods
tion only.
4.1 Specimens of the crosslinked ethylene plastic are
NOTE 1—ISO 10147 is similar to this test, but is not equivalent.
weighed and then immersed in the extracting solvent at the
temperature specified by the procedure selected and for the
1.5 This standard does not purport to address all of the
time designated by that procedure.After extraction, the speci-
safety concerns, if any, associated with its use. It is the
mens are removed, dried, and reweighed as directed. The
responsibility of the user of this standard to establish appro-
amountofmaterialextractediscalculatedand,ifdesired,swell
priate safety and health practices and determine the applica-
ratio also may be determined by the means described in
alternative Test Method C.
1
These test methods are under the jurisdiction of ASTM Committee D20 on
2
Plastics and are the direct responsibility of Subcommittee D20.15 onThermoplastic For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Materials. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved June 10, 2001. Published August 2001. Originally Standards volume information, refer to the standard’s Document Summary page on
published as D2765–68. Last previous edition D2765–95. 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
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.