(191b) Polyethylene-Solvent Solubility and Diffusivity – Problems and Solutions?

The production of polyethylene (PE) is the largest volume polymer production in the world.  About 40% of all polymer resins are PE.  The complementary intensive market competition makes even small advances in production efficiency a potentially large financial gain.  Because of the wide variety of products made from PE that range in importance from waste cans to medical devices, health and safety issues are often paramount.  Residual solvents and monomers must be removed to very low levels as efficiently as possible.

      There are many varieties of PE ranging from very-low-density to ultra-high-molecular-weight PEs.  Each of these brings some unique characteristic into the picture.  This presentation will examine some of the problems in and solutions to analyzing PE resins to meet the health and safety requirements.  These include experimental methods of measuring solubility and diffusion at low concentrations of organic components; models that can be used to predict the solubility or correlate the diffusivity; effects of crystals; the potential for adding an additional material to improve these characteristics; the difficulty in analyzing diffusion in the typical porous pellets that are produced in many of the processes; the changes that can be expected as the processing passes through the glass transition temperature.