Self-healing slip pulses and the friction of gelatin gels
Self-healing slip pulses and the friction of gelatin gels
复制标题
自愈滑动脉冲和明胶凝胶的摩擦
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
O. Ronsin
中科院分区：
文献类型：
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作者：
T. Baumberger;C. Caroli;O. Ronsin
摘要：我们对明胶凝胶在玻璃上的摩擦进行了广泛的实验研究和缩放分析。在低驱动速度下，滑动是通过周期性自愈滑动脉冲的传播而发生的，其速度受到凝胶网络的集体扩散的限制。愈合可归因于滑移速度 V = Vc 时发生的摩擦不稳定。当 V > Vc 时，滑动是均匀的，摩擦力由厚度为（纳米）网格尺寸的界面层的剪切稀化流变性决定，其中包含悬挂在网络上的聚合物链末端的溶液。尽管其高度限制，该系统的流变学与已知的散装系统没有本质上的区别。观察到的静摩擦阈值的老化揭示了链端和玻璃之间的粘合力缓慢增加。这种结构老化与速度小于 Vc 时速度弱化区域的存在相容，因此与愈合不稳定性的存在相容。
Abstract:We present an extensive experimental study and scaling analysis of friction of gelatin gels on glass. At low driving velocities, sliding occurs via propagation of periodic self-healing slip pulses whose velocity is limited by collective diffusion of the gel network. Healing can be attributed to a frictional instability occurring at the slip velocity V = Vc. For V > Vc, sliding is homogeneous and friction is ruled by the shear-thinning rheology of an interfacial layer of thickness of order the (nanometric) mesh size, containing a solution of polymer chain ends hanging from the network. In spite of its high degree of confinement, the rheology of this system does not differ qualitatively from known bulk ones. The observed ageing of the static friction threshold reveals the slow increase of adhesive bonding between chain ends and glass. Such structural ageing is compatible with the existence of a velocity-weakening regime at velocities smaller than Vc, hence with the existence of the healing instability.