Fig. 6

Elastic and loss moduli of freshly opened Curosurf samples as a function of the angular frequency (\(\:\text{T}\) = +37 °C). The cone-and-plate measurements were performed in the linear regime of deformation (\(\:{{\upgamma\:}}_{0}\) = 5%). The straight lines through the data points result from best-fit calculations using power-law functions of the form \(\:{\text{G}}^{{\prime\:}}\left({\upomega\:}\right)\:\sim\:{{\upomega\:}}^{{\upalpha\:}}\) and \(\:{\text{G}}^{{\prime\:}{\prime\:}}\left({\upomega\:}\right)\:\sim\:{{\upomega\:}}^{{\upbeta\:}}\), with exponents \(\:{\upalpha\:}\) = 0.38 and \(\:{\upbeta\:}\) = 0.56. B) \(\:{\text{G}}^{{\prime\:}}\left({\upomega\:}\right)\) and \(\:{\text{G}}^{{\prime\:}{\prime\:}}\left({\upomega\:}\right)\) obtained from a Curosurf sample shortly opening, after one day and after one month. After opening, the dispersion was kept at + 4 °C in the dark. The plateau in modulus \(\:{\text{G}}^{{\prime\:}}\left({\upomega\:}\right)\) after one month suggests viscoelastic gel behavior.