This test method is designed to produce data indicative of the degree of crosslinking in ultra high molecular weight polyethylene that has been crosslinked chemically or by ionizing radiation.

The results are sensitive to the test temperature, solvent, and method used. For the comparison of data between institutions, care must be taken to have the same test conditions and reagents.

The data can be used for dose uniformity analysis, fundamental research, and quality assurance testing.

1.1 This test method describes how the crosslink density, molecular weight between crosslinks, and number of repeat units between crosslinks in ultra-high molecular weight polyethylene (UHMWPE) crosslinked by ionizing radiation or by chemical means can be determined by measuring the swelling ratio of samples immersed in o-xylene. Examples of experimental techniques used to make these measurements are discussed herein.

1.2 The test method reported here measures the change in height of a sample specimen while it is immersed in the solvent. Volumetric swell ratios assume that the sample is crosslinked isotropically, and that the change in dimension will be uniform in all directions. This technique avoids uncertainty induced by solvent evaporation or temperature change.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 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.