Small-angle neutron scattering from deuterated polystyrene in dioctyl phthalate solution under shear

TitleSmall-angle neutron scattering from deuterated polystyrene in dioctyl phthalate solution under shear
Publication TypeJournal Article
Year of Publication1992
AuthorsHammouda, B., Nakatani A. I., Waldow Dean, and Han C. C.
JournalMacromolecules
Volume25
Issue11
Pagination2903-6
AbstractSmall-angle neutron scattering of high-mol.-wt. (1.95 x 106) polystyrene in dioctyl phthalate solns. was measured at low concn. (3% wt. fraction) under steady shear with rates ranging from the quiescent condition (0 s-1) to 1100 s-1 at room temp. (22.degree.). The scattered intensity increased dramatically beyond a characteristic shear rate (.gamma.c = 57 s-1) similar to the increase following a temp. drop from the one-phase region (ambient temp.) to the two-phase region in this upper crit. soln. temp. system. The RPA approach (the Zimm inverse scattering formula) was used along with a swollen radius of gyration in the Debye function to analyze the data and ext. a statistical segment length b and a polymer-solvent interaction parameter .CHI.ps. The segment length increased slightly, indicating a slight increase in chain vol. beyond .gamma.c, while the interaction parameter showed a dramatic increase up to the spinodal value .gamma.s = 280 s-1 where the RPA breaks down, therefore giving nonreliable values.