1. 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 xylenes. 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 xylenes at a constant temperature of 110C. 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 standard. The inch-pound units in brackets are for information only. ISO 10147 is similar to this test, but is not equivalent.

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 , , and .

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ISO Standard

ASTM Standards

D297 Test Methods for Rubber Products--Chemical 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

Keywords

crosslinked ethylene plastics; gel content; insoluble fraction; swell ratio: Crosslinking; Decahydronaphthalene extraction; Ethylene plastics; Gels (fisheyes) content; Insulated wire and cable; Nonreferee method; Referee methods; Swelling; Xylene;

ICS Code

ICS Number Code 83.080.20 (Thermoplastic materials)

DOI: 10.1520/D2765-01R06

ASTM International is a member of CrossRef.