Polyethylene standard reference polymers

The next polymer Standard Reference Materials, issued in 1970, were a linear and a branched polyethylene. They are representative of crystalline olefin polymers, which have assumed great commercial and scientific importance. The linear material was kindly provided by the Dupont Co. and the branched by Union Carbide Corp. 

Standard Reference Material 1475, Linear Polyethylene (Whole Polymer)... 

Three methods are common, viz, the liquid displacement method, the sink-float method and the density gradient column method. Each of these is a common, standard technique and is fully described in ISO 10119, 1992 (for the determination of the density of carbon fiber), and also in ASTM D 276-87 (reapproved in 1993), which in fact also refers to ASTM D 1505, ASTM D 792, and AATCC, Method 20 (1990) (Fiber identification), each of which deals with the above techniques. ISO 10119 is a very good and concise description of the techniques. However the measurement liquids specified in ISO 10119 of ethanol, methanol, acetone, tricloroethane, and carbon tetrachloride, although suitable for carbon fibers, are not at all suitable for the general range of textile polymers, with the exception perhaps of ethanol and methanol. ASTM D 276 87 recommends the use of / -Heptane for universal application, except, of course for the olefins, such as polyethylene. A range of typical fiber densities is given in Table 4. 

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