Print version ISSN 0104-1428
BIANCHI, Otávio et al. Viscometric characterization of PS/POSS hybrid nanocomposites. Polímeros [online]. 2012, vol.22, n.2, pp.125-133. Epub Apr 10, 2012. ISSN 0104-1428. http://dx.doi.org/10.1590/S0104-14282012005000022.
Polystyrene (PS) and polyhedral oligomeric silsesquioxanes (POSS) hybrid nanocomposites with different compositions were obtained by reactive melt processing using dicumyl peroxide (DCP) as initiator in the presence or absence of styrene as radical transfer agent. The materials were characterized by viscosimetry by means of gel permeation chromatography (GPC) using triple-detector: light scattering, viscometer and refractive index. PS/POSS samples processed with styrene showed higher weight average molecular weights (Mw) and lower polydispersity indexes (Mw/Mn), as a result of higher PS-POSS conversion (28-40%) and lower PS degradation, as compared to the PS/POSS samples processed without styrene in which the degree of conversion was lower (24-28%). For the PS/POSS solutions in THF, the parameters of the Mark-Houwink-Sakurada equation, α ≅ 0.7 and log K ≅ -3.5 to -3.9, and the values of polymer-solvent interaction parameter, χij ≅ 0.49, were not changed with respect to changes in molecular size. On the other hand, these changes were characterized by a cumulative function of the mass fraction of chains as a function of the root mean square end to end distance (< r2 >01/2).
Keywords : PS; POSS; hybrid nanocomposites; viscosimetry.