Agarose hydrogels are poroviscoelastic materials that exhibit a waterlogged-crosslinked microstructure. Despite an extensive use in biotechnologies and numerous studies of the elastic properties of agarose gels, little is known about the compressible behavior and the microstructural changes of such fibrillar hydrogels under compression. The present work investigates the mechanical response of centimeter-sized pre-molded agarose cylinders when applying a compressive strain ramp over an extended range of loading speed and polymer concentration. One of the original contributions is the simultaneous monitoring of the changes in the hydrogel volume to determine the Poisson’s ratio through a spatiotemporal method. The linear poroelastic response of agarose hydrogels shows a compressible behavior at strain rates less than 0.7 % s⁻¹. The critical compressive strain of a few percent at the onset of the non-linear regime and the always positive Poisson’s ratio decrease when applying a slow compressive ramp. The mechanical response in the linear regime is typical of a deformation mode either dominated by the bending of semiflexible strands (enthalpic regime) or by the stretching of the network (entropic regime) at higher agarose concentration. Cyclic linear shear deformations superimposed to a compressive strain from 0.5 up to 40% further give evidence of a compression-softening of the network causing the transition to the non-linear regime without dependence upon the network topology and connectivity. Finally, the buckling-induced aging of the network under a weak compression and the poroviscoelasticity of the hydrogel are shown to impact the relaxation of the normal stress and the equilibrium stress.

琼脂糖水凝胶是表现出浸水交联的微观结构的多孔粘弹性材料。尽管在生物技术中得到了广泛应用，并且对琼脂糖凝胶的弹性特性进行了许多研究，但人们对这种纤维状水凝胶在压缩状态下的可压缩行为和微观结构变化知之甚少。本工作研究了在扩展的加载速度和聚合物浓度范围内施加压缩应变斜坡时，厘米大小的预成型琼脂糖圆柱体的机械响应。最初的贡献之一是通过时空方法同时监测水凝胶体积的变化，以确定泊松比。琼脂糖水凝胶的线性多孔弹性响应显示出应变率小于0.7％s时的可压缩行为^-1。当施加缓慢的压缩坡度时，非线性状态开始时的临界压缩应变为百分之几，并且始终为正的泊松比降低。线性状态下的机械响应是变形模式的典型特征，变形模式主要由半柔性线的弯曲（焓模式）或较高琼脂糖浓度下的网络拉伸（熵模式）主导。叠加在0.5至40％的压缩应变上的循环线性剪切变形进一步证明了网络的压缩软化会导致过渡到非线性状态，而无需依赖于网络拓扑和连通性。最后，