Dynamics of flow-induced surface exchange

Near‐surface dynamics of sheared polymer melts using ATR/FTIR

“…In light of the preceding, we must conclude that the previous results (Dietsche et al, 1995;David et al, 1995) with hexadecene/hexadecane were indicative of extremely slow near-surface dynamics, orders of magnitude slower than reported in simulations. To confirm those results, we repeated the experiments with C,,'s on the same surface as the PB experiments outlined earlier.…”

“…The experimental setup has been described in detail by Dietsche (1993) and David (1994). A brief description, including some minor modifications.…”

“…Previous investigations in our laboratory using attenuated total-reflection infrared spectroscopy (ATR/FTIR) (Dietsche et al, 1995;David et al, 1995) demonstrated the existence of surprisingly-long time scales for the diffusion of linear oligomers (C,,'s) away from a flat surface under mild flow conditions. Although the most marked departure from simple diffusion occurred with hexadecane functionalized by polar groups (carboxylic acids, alcohols, amines), anomalously slow diffusion occurred even in the case of the interdiffusion of hexadecane and 1-hexadecene, which should have weak interactions with the surfaces used in these experiments.…”

Enhanced Polymer Segment Exchange Kinetics Due to an Applied Shear Field

“…Much work has been performed to determine the important physical parameters for wall slip and to understand the underlying mechanisms of the behavior of polymers at solid boundaries with the goal of better designing processing routes. − However, the effect of flow on the microscopic behavior of polymer chains directly at a solid surface is not well understood. Few experimental data are available for the behavior of polymer melt chains at the solid interface because of the inherent difficulty of distinguishing between surface-bound chains and the melt matrix. − …”

“…Few experimental data are available for the behavior of polymer melt chains at the solid interface because of the inherent difficulty of distinguishing between surfacebound chains and the melt matrix. [13][14][15] In this communication, neutron reflectometry was used to study the effect of a shear deformation on the adsorption/desorption kinetics of an entangled polymer melt at an attractive solid substrate. The high spatial resolution of neutron reflectivity, O (Å), provides information directly at the polymer/solid interface.…”