Nonlinear Viscoelastic Properties of Semisolid Emulsions

Abstract

The dynamic viscoelastic properties of semisolid emulsions (commercial cosmetic creams) at 25°C were measured by means of a Weissenberg rheogoniometer at frequencies ranging from 1.582×10−3 to 1.582 Hz. In general, these emulsions manifested remarkable nonlinear viscoelasticity even at very small strains; when sinusoidal strains were applied to the emulsions, the resultant stresses were not sinusoidal, in marked contrast to the case in ordinary linear viscoelastic materials. Such nonsinusoidal stresses were analyzed by the method proposed by Onogi et al. to give nonlinear viscoelastic functions. The frequency dependences of these nonlinear functions for the emulsions were quite different from those of the viscoelastic functions for polymer solutions or melts, especially in the low frequency range; the viscoelastic functions for the semisolid emulsions showed second plateaus lower than the so-called rubbery plateau. Some considerations concerning the origin of the nonsinusoidal stresses were given, and it was concluded that the origin was the dynamic yield stress which was originated from the structure in the semisolid emulsions.

A review of nonlinear oscillatory shear tests: Analysis and application of large amplitude oscillatory shear (LAOS)

“…From the 1960's to 1970's, early publications [9][10][11][12][13][14][15][16][17][18][19] investigated nonlinear phenomena for various viscoelastic materials under oscillatory shear and proposed the methods of Fourier transform analysis and stress waveform analysis. Technical problems severely hindered further progress at that time, specifically hardware and software limitations such as torque transducer resolution and computational power.…”

“…They found that the ratios of , respectively, were of the order of 10% at an applied shear strain amplitude γ 0 = 0.26. Komatsu et al [17] investigated the nonlinear viscoelastic behavior of two kinds of semisolid emulsions; one was an oil-in-water type and the other was water-in-oil type (commercial cosmetic creams). They compared the stress shape as a function of time including the analysis of higher Fourier components as proposed by Onogi et al [14].…”

“…They compared the stress shape as a function of time including the analysis of higher Fourier components as proposed by Onogi et al [14]. Philippoff [13], Onogi et al [14], Dodge and Krieger [15], Matsumoto et al [16], and Komatsu et al [17] used Fourier transform analysis of stress data. Tee and Dealy [18] investigated the nonlinear viscoelastic properties of three polymer melts (HDPE, LDPE, and PS).…”

“…For the case of a single mode, the evolution of the state of stress in the network model can be written in terms of the creation and loss functions as follows [64,80] (17) where the constants a and b are model parameters defining the creation and loss rates, respectively.…”

“…As a result, LAOS type II behavior is found when the creation rate parameter is positive (a > 0) and greater than 2b (a > 2b), see Eq. (16) and (17). At large strain amplitude, the governing equations of the network model become numerically stiff due to the large positive exponents.…”