where [[eta]] is the intrinsic viscosity (dL [g.sup.-1]), Mv is the average
viscosimetric molar mass, and K and [alpha] are constants for a given polymer-solvent system, which, in the case of chitosan, varies according to the DA as well as molecular weight range.
Viscosimetric measurements were done to evaluate the influence of the catalysts and reaction time in the growth of silsesquioxane oligomers derived from sol-gel hydrolysis and condensation of APES and PTES.
[M.sub.v] and [M.sub.w] are the
viscosimetric molar mass and the weight average molar mass determined by gel permeation chromatography, respectively.
A Water GPC-V 200 instrument equipped with both refractive index and
viscosimetric detectors was used for the analysis of molecular weight [M.sub.n] and [M.sub.w] dispersity index ([I.sub.d] = [M.sub.w]/[M.sub.n]) and the branching ratio g' defined as the ratio between the intrinsic viscosity of the sample and the calculated intrinsic viscosity of the linear polymer.
According to a Mark-Howink-type equation [34, 35], [eta] = 5.45.[10.sup.-4] [M.sub.v.sup.0.73]; this value corresponds to a
viscosimetric molecular weight of [M.sub.v] = 323,800 g/mol.
The material used in this work shows an intrinsic viscosity of 0.84 dL/g, which corresponds to an average molecular weight of about 18,000 when the
viscosimetric equation of nylon 6 6 is applied for calculation.
