configuration that the macromolecule adopts in solution. Values closer to 0.8 indicate that the polymer is in a good solvent. If constants for a specific polymer–solvent system are not reported in the literature, they can be obtained experimentally using monodisperse polymers of known MW. If Equation 17.18 is plotted in the log–log scale, the intercept will give the value of log (K) while the slope will provide an estimate of α. The slope is related to the shape of the polymer molecules and the polymer–solvent interactions. For a polymer under theta conditions (unperturbed random coil), α = 0.5. For a polymer in a good solvent, α = 0.8; while for rodlike polymers α = 2 [41]. van Krevelen [41] also provides some criteria to estimate α, which is based on the solubility parameters of the polymer and the solvent. It is important to point out that the Mark-HouwinkSakurada equation does not apply to polymers with low MWs, as indicated in the literature [29]. Nowadays, the new GPC hardware can have different detectors coupled, such as viscosity detectors, which allow measurements in situ of the intrinsic viscosity of polymers as well as the constants K and α. Using this advanced equipment, one can obtain the MW and intrinsic viscosities of polymers in a very short time.