Bayreuth 1998 – scientific programme

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PO: Polymerphysik

PO 2: Phasenverhalten und Strukturbildung

PO 2.1: Talk

Wednesday, March 11, 1998, 10:45–11:05, Audimax

Equilibrium Phase Diagram of Blends of Linear and Branched Polyethylene by Nuclear Reaction Analysis (NRA) — •R. Magerle¹, D.J. Lohse², and J. Klein¹ — ¹Materials and Interfaces Dept., Weizmann Institute of Science, Rehovot 76100, Israel — ²Exxon Research and Engineering Co., Route 22 East, Annandale, NJ 08801, USA

In recent years different views have been expressed about the miscibility of linear and branched polyethylene (HDPE and LDPE, respectively) ranging from liquid-liquid phase segregation [1] to complete homogeneity in the melt [2]. We have studied binary HDPE/LDPE pairs very similar to those studied earlier by small angle neutron scattering (SANS) and for which different interpretations have been proposed. In contrast to SANS, where the concentration distribution of the deuterated component of a polymer mixture is studied in Fourier space, with NRA the concentration-versus-depth profiles of the deuterated component is measured in real space and with nanometer resolution perpendicular to the phase boundary between the two components. In this way the concentration of the deuterium-labeled component in both coexisting phases can be determined and the equilibrium phase diagram constructed.

[1] P.J. Braham et al., J. Mater. Sci. Lett. 7, 1271 (1988); C. Schipp et al., Polymer 37, 2291 (1996).

[2] R.G. Alamo, et al., Macromolecules 27, 411 (1994); R.G. Alamo et al., Macromolecules 30, 561 (1997).