V.S. Ismailov1

1 Comprehensive Scientific Research Institute n.a. H.I. Ibragimov of the RAS (Grozny, Russia)
1 vis_089@mail.ru

When determining surface dynamic viscosity by the oscillating drop method, the classical Lucassen–van den Tempel model has fundamental limitations, especially when analyzing unsteady and noisy signals at high and low frequencies. An additional error is introduced by hidden digital filtering embedded in the default tensiometer software, which leads to artificial modification of the primary signal and loss of its physical reliability.

To increase the objectivity and noise immunity of calculations of surface dynamic viscosity by modifying the classical Lucassen–van den Tempel model and comparative evaluation of amplitude and integral approaches.

The disadvantages of amplitude analysis in terms of real experimental data are shown. The classical model is modified by switching from an amplitude to an integral approach that takes into account the full time series of strain and stress. Based on the fundamental principles of Lucassen's theory, a universal integral formula is proposed that operates with root-mean-square values and the energy balance of the oscillatory process.

The proposed universal integral formula (integral method) provides high noise immunity and objective calculations without the need for pre-filtering, allowing for more reliable data on the rheological properties of interphase boundaries under difficult experimental conditions. Compared with the amplitude approach, this method increases the accuracy of determining the surface dynamic viscosity by 30-50% when working with the original, unmodified data set.

Ismailov V.S. An integral approach to the determination of surface dynamic viscosity as an alternative to the Lucassen – van den Tempel model // Nanotechnology: development and applications – XXI century. 2026. V. 18. № 2. P. 56–63. DOI: https://doi.org/10.18127/ j22250980-202602-06

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