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PO: Polymerphysik

PO 8: Poster: Polymermischungen und Copolymere

PO 8.11: Poster

Dienstag, 2. März 1999, 14:00–16:00, Foyer

The role of macromolecular mobility in adhesive behaviour of hydrophilic polymer blends. — •A. E. Chalykh¹, G. Fleischer², and M. M. Feldstein³ — ¹Institute of Physical Chemistry, RAS, Moscow — ²Universität Leipzig, Fakultät f. Physik und Geowiss., 04103 Leipzig — ³A. V. Topchiv Institute for Petrochemical Synthesis, RAS, Moscow

The pressure sensitive adhesion in miscible blends of high molecular poly(N-vinyl pyrrolidone) (PVP) with short chain poly(ethylene glycol) (PEG) is the result of the stoichiometricH-bond complex formation between OH-groups on the ends of PEG and the carbonyls in the units of longer PVP chains. Based on the glass transition temperatures of the adhesive PVP-PEG hydrogels the heat mobility of the macromolecular segments has been evaluated in the terms of polymer chain microviscosity and interdiffusion coefficients. Those are rather intrinsic to polymer liquids than to solids. High molecular mobility of macromolecular segments is necessary to involve as much adhesive as possible into the resistance to adhesive bond rupture. The unequivocal correlation of the strength of adhesive joint is found with the other important measure of the molecular mobility: the jump in polymer heat capacity at the glass transition. All the pressure-sensitive adhesives posses a minimum magnitude of the change in heat capacity at their glass transition temperatures. This finding highlights the specific balance between molecular cohesion energy of polymeric segments and fluctuational free volume as a major determinant of polymer blend adhesive behaviour at a molecular level.