Di(2-ethylhexyl) phthalate (DEHP) is a commonly employed plasticizer for poly(vinyl chloride) (PVC). Diffusion of di(2-ethylhexyl) phthalate (DEHP) takes place when plasticized PVC is immersed in hexane. Rather than determining DEHP concentration in the immersion solvent, an IR window for PVC from 1500-1900 cm-1 enabled direct measurement of HADD (hexane assisted DEHP diffusion) using ATR-IR by monitoring the DEHP carbonyl absorption at 1715 cm-1. The present study employed PVC containing 45% plasticizer (PVC-45, tygon tubing). A fast diffusion process was observed for short times (< 30 s) while a slower diffusion process occurred at longer immersion times (30 s < t < 6 min). A synergistic increase in mesosurface T g toward that of PVC coupled with low solubility of hexane in PVC accounts for decreased DEHP diffusion rates (10-12-10-13 cm 2 sec-1) for immersion times > 30 sec. Analysis by XPS shows the outermost surface is PVC free of plasticizer after 6 min immersion. After an induction period, back diffusion coefficients D b were estimated from peak areas during a subsequent fast recovery period (10-14-10-15 cm 2 sec-1). A model is proposed for the induction period associated with re-plasticization that involves a change from a mesosurface glass to a gel like solid.

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Nichts dem Zufall überlassen: Über den schnellen und reversiblen Austausch zwischen „festen“ und „lockeren“ Ionenpaaren wurden die relativen Reaktivitäten von Ethen und 1‐Hexen oder Cyclopenten bei der lebenden Koordinations‐Kettentransfer‐Polymerisation moduliert. So konnten unterschiedliche Grade eines monodispersen Polyolefin‐Copolymers, z. B. die gezeigten Poly(ethen‐co‐1‐hexene), mit einem einzigen kationischen Übergangsmetallkatalysator erhalten werden.