NEAR-SURFACE DYNAMICS OF SHEARED POLYMER MELTS USING ATR FTIR/

Using attenuated total-reflectance infrared spectroscopy (ATR/FTIR), t he concentration of deuterated polybutadiene near the surface of a fla t zinc selenide crystal was followed as it was replaced by ordinary po lybutadiene by flow and diffusion. Experiments were performed in the m elt, both below (M similar to 1,500) and above (M similar to 15,000) t he entanglement threshold. The decay profiles agree well with a finite -element simulation of the system. In contrast to previous investigati ons of C-16's, the decay profiles of both unentangled and entangled po lybutadienes are consistent with a uniform diffusivity in the near-wal l region.