AN UNLIKELY INTRODUCTION TO FICK'S SECOND LAW OF DIFFUSION: PVC AND TYGON TUBING

摘要

Polymer or "soft" surface science offers rich and diverse opportunities for education, but often experiments are quite complex or irrelevant to education in chemical engineering. Herein, we describe a laboratory experiment using a commonplace material, Tygon tubing, which is [poly(vinylchloride), PVC] plasticized with dioctylphthalate (DOP). A novel determination of the diffusion coefficient for hexane assisted DOP diffusion has been developed using Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy. The procedure involves exposing sections of tubing to solvent for short time intervals. The area of the DOP carbonyl peak, which occurs in a PVC "IR window" is monitored vs. time. The peak areas are analyzed using Fick's second law of diffusion.