Leipzig 1999 – scientific programme

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PO: Polymerphysik

PO 8: Poster: Polymermischungen und Copolymere

PO 8.4: Poster

Tuesday, March 2, 1999, 14:00–16:00, Foyer

Phase separation kinetics of polymer blends studied by small angle light scattering: pressure and temperature jump experiments — •Maximilian Ruellmann, Bernd Steinhoff, and Ingo Alig — Deutsches Kunststoff-Institut, Schlossgartenstr. 6, 64289 Darmstadt

Small angle light scattering experiments have been performed to investigate the phase separation kinetics in an off critical mixture of polypropylene glycol and polyethylene glycol. The two-phase region of the phase diagram was entered by two different quench methods: pressure jump and temperature jump. After the pressure jumps a spinodal ring was apparent, indicating spinodal decomposition. In the late stage of demixing a self similar structure evolution was observed. After the temperature jump to the same final temperature the scattering was that of an ensemble of spherical droplets. An analysis of the radius growth showed that the decomposition started in the binodal region of the mixing gap. In the late stage the phase separation was pinned possibly due to hydrogen bonds between the glycol molecules implying a suppressed diffusion. Using the pressure jump method the demixing kinetics was also investigated dependent on quench depths.