Verweij Joanne E, Leermakers Frans A M, Sprakel Joris, van der Gucht Jasper
Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
Soft Matter. 2019 Aug 28;15(32):6447-6454. doi: 10.1039/c9sm00686a. Epub 2019 Jul 22.
Colloidal gels are space-spanning networks of aggregated particles. The mechanical response of colloidal gels is governed, to a large extent, by the properties of the individual gel strands. To study how colloidal gels respond to repeated deformations, we perform Brownian dynamics simulations on single strands of aggregated colloidal particles. While current models assume that gel failure is due to the brittle rupture of gel strands, our simulations show that gel strands undergo large plastic deformations prior to breaking. Rearrangement of particles within the strands leads to plastic lengthening and softening of the strands, which may ultimately lead to strand necking and ductile failure. This failure mechanism occurs irrespective of the thickness and length of the strands and the range and strength of the interaction potential. Rupture of gel strands is more likely for long and thin strands and for a long-ranged interaction potential.
胶体凝胶是由聚集颗粒构成的跨越空间的网络。胶体凝胶的力学响应在很大程度上由单个凝胶链的性质决定。为了研究胶体凝胶如何响应反复变形，我们对聚集胶体颗粒的单链进行了布朗动力学模拟。虽然目前的模型认为凝胶失效是由于凝胶链的脆性断裂，但我们的模拟表明，凝胶链在断裂前会经历大的塑性变形。链内颗粒的重排导致链的塑性伸长和软化，这最终可能导致链的颈缩和韧性失效。这种失效机制与链的厚度和长度以及相互作用势的范围和强度无关。长而细的链以及长程相互作用势更容易导致凝胶链的断裂。
