Aqueous foams are dispersions of gas bubbles in water, stabilized by surfactant, and sometimes particles. This multiphasic composition gives rise to complex rheological behavior under deformation. Understanding this behavior is important in many applications. Foam shows nonlinear rheological behavior at high deformation, which can be investigated by the large amplitude oscillatory shear (LAOS) experiments. In the present work, we have performed a systematic LAOS study of foam stabilized by 0.1 mol m⁻³ hexadecyltrimethylammonium bromide and 0.5 wt.% silica nanoparticles. The Lissajous-Bowditch curves and stress waveforms were analyzed at various strain amplitudes. These curves were fitted by Fourier transform rheology and Chebyshev polynomials to understand the contribution of the higher harmonic terms in LAOS. The intracycle LAOS behavior was explained based on the sequence of physical processes. The foam exhibited intracycle strain-hardening and shear-thinning at high deformation. Shear-thickening behavior was observed at moderate deformations.

中文翻译：

---

泡沫在大振幅振荡剪切流作用下的非线性粘弹性行为

水性泡沫是气泡在水中的分散体，通过表面活性剂稳定，有时还可以是颗粒。这种多相组成在变形下引起复杂的流变行为。了解此行为在许多应用程序中很重要。泡沫显示出高变形下的非线性流变行为，这可以通过大振幅振荡剪切（LAOS）实验来研究。在目前的工作中，我们对0.1 mol m ^-3稳定的泡沫进行了系统的LAOS研究。十六烷基三甲基溴化铵和0.5重量％的二氧化硅纳米粒子。分析了不同应变幅度下的李萨如-鲍迪奇曲线和应力波形。这些曲线通过傅立叶变换流变学和Chebyshev多项式拟合，以了解LAOS中高次谐波项的贡献。基于物理过程的顺序来解释周期内LAOS行为。该泡沫在高变形下表现出循环内应变硬化和剪切稀化。在中等变形下观察到剪切增厚行为。