W0133

Lamellar Scattering versus Supramolecular Scattering in Semi-Crystalline Polymers. John D. Barnes. Polymer Structure and Mechanics Group, NIST, Gaithersburg, MD 20899, USA

Recent studies on syndiotactic polystyrene[1] (sPS) have demonstrated that the observed SAXS patterns are the superposition of two components: (1) a strongly peaked component arising from the lamellar organization of the crystallizable microstructural elements and (2) a component that varies smoothly as q^-d where d ~2.5 over most of the observable q range. The fact that sPS exhibits virtually no electron density contrast between its crystalline and amorphous regions below its glass temperature (T_g ~ 100 [ring]C) is a fortuitous occurrence that allows us to separate the aforementioned contributions by varying the specimen temperature in SAXS experiments between room temperature and approximately 200 [ring]C, which is still well below any temperature at which annealing takes place. The power law behaviour found in sPS implies the presence of density fluctuations whose character is distinct from the liquidlike behavior normally ascribed to amorphous polymers. This presentation extends the interpretation of the earlier data on sPS and adds results from several other polymers in an attempt to see if the two-component picture is applicable to other semicrystalline polymers.

[1] Barnes, J. D.; McKenna, G. B.; Landes, B. G.; Bubeck, R. A.; Bank, D.; Polymer Eng and Sci, V37, No. 9, pp 1480-4.