Pouzot Matthieu, Nicolai Taco, Benyahia Lazhar, Durand Dominique
Polymères, Colloïdes, Interfaces, UMR-CNRS, Université du Maine, 72085 le Mans Cedex 9, France.
J Colloid Interface Sci. 2006 Jan 15;293(2):376-83. doi: 10.1016/j.jcis.2005.06.074. Epub 2005 Aug 2.
Non-linear mechanical behavior at large shear deformation was been investigated for heat-set beta-lactoglobulin gels at pH 7 and 0.1 M NaCl using both oscillatory shear and shear flow. These gels have a self-similar structure at length scales smaller than the correlation length of the gel with fractal dimension d(f)=2. Strain hardening is observed that can be well described using the model proposed by Gisler et al. [T.C. Gisler, R.C. Ball, D.A. Weitz, Phys. Rev. Let. 82 (1999) 1064] for fractal colloidal gels. The increase of the shear modulus normalized by the low strain value (G(0)) is independent of G(0). For weak gels the elasticity increases up to a factor of ten, while for strong gels the increase is very small. At higher deformation irreversible fracture occurs, which leads eventually to macroscopic failure of the gel. For weak gels formed at low concentrations the deformation at failure is about 2, independent of the shear modulus. For strong gels fracture occurs at approximately constant stress (2 x 10(3) Pa).
使用振荡剪切和剪切流研究了在pH 7和0.1 M NaCl条件下热凝固的β-乳球蛋白凝胶在大剪切变形下的非线性力学行为。这些凝胶在小于凝胶关联长度的长度尺度上具有自相似结构，分形维数d(f)=2。观察到应变硬化现象，这可以用Gisler等人 [T.C. Gisler, R.C. Ball, D.A. Weitz, Phys. Rev. Let. 82 (1999) 1064] 提出的分形胶体凝胶模型很好地描述。通过低应变值（G(0)）归一化的剪切模量的增加与G(0)无关。对于弱凝胶，弹性增加高达十倍，而对于强凝胶，增加非常小。在更高的变形下会发生不可逆断裂，最终导致凝胶的宏观失效。对于在低浓度下形成的弱凝胶，失效时的变形约为2，与剪切模量无关。对于强凝胶，断裂发生在大约恒定的应力（2×10³ Pa）下。
