|Importance of Additive Extraction Stressed in New Plastics Standard
Quality control scientists, plant processing engineers and polymer formulation scientists are the most likely users of a new ASTM International standard, D 7210, Practice for Extraction of Additives in Polyolefin Plastics. The standard was developed by Subcommittee D20.70 on Analytical Methods, which is under the jurisdiction of ASTM International Committee D20 on Plastics. Practice D 7210 covers a variety of extraction techniques for antioxidant and slip additives used in polyolefins.
“Polymer formulation is both art and science,” says Richard Carlson, staff chemist, Dionex. “In addition to monomers that lead to the macromolecules known as polymers, hundreds of compounds have been produced that, when properly formulated and combined with a polymer, produce different properties.”
According to Carlson, it is necessary to separate and identify all polymer additives to correlate performance properties with polymer composition. The many additives used in polymers account for such properties as clarity (e.g., to produce clear rather than cloudy drinking cups), flexibility (e.g., PVC is used for piping and shower curtains) and stability (e.g., to reduce or prevent degradation caused by exposure to sunlight). In addition, additives are used in polymers to assist processing, modify bulk mechanical and surface properties, prevent aging and change optical effects.
While not all additives are used in every polymer, the process is complicated by the fact that each polymer will have some variation due to production, such as density. The extraction techniques described in Practice D 7210 are important because small variations in extraction solvents may be required in the polymers under examination.
Committee D20 welcomes any participation from interested parties in the further development of D 7210. “I believe that ASTM standards should be most relevant to end users,” says Carlson. “As such, we actively seek and welcome participation from people doing the experiments in the laboratory and laboratory/quality control group leaders.”
Technical Information: Richard Carlson, Dionex, Salt Lake City, Utah
ASTM Staff: Katharine Morgan
November Committee Week