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ASTM

D2238-22

Standard Test Methods for Absorbance of Polyethylene Due to Methyl Groups at 1378 cm−1

2022

7

ASTM Vol.08.01 (2022)

These test methods cover measurement by infrared absorption spectrophotometry of the 1378 cm−1 (7.25 μm) band in polyethylene due to methyl groups. (123-6)2 Two test methods are covered: Test Method A uses compensation with a standard sample film of known methyl content. Test Method B uses compensation with a wedge of polymethylene or a polyethylene of known low methyl content. These test methods are applicable to polyethylenes of Types I (density 0.910 to 0.925 g/cm3), II (density 0.926 to 0.940 g/cm3), and III (density 0.941 to 0.965 g/cm3). NOTE 1: For determination of density, see Specifications D1505NOTE 2: In cases of Type III polyethylene with densities greater than 0.950 g/cm3, different results are obtained with the two test methods. The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

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