School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, PR China.
J Mech Behav Biomed Mater. 2013 Jul;23:22-31. doi: 10.1016/j.jmbbm.2013.03.021. Epub 2013 Apr 10.
Many models describing the deformation of general foam or auxetic materials are based on the assumption of homogeneity and order within the materials. However, non-uniform heterogeneity is often an inherent nature in many porous materials and composites, but difficult to measure. In this work, inspired by the structures of auxetic materials, the porous PVA hydrogels with internal inby-concave pores (IICP) or interconnected pores (ICP) were designed and processed. The deformation of the PVA hydrogels under compression was tested and their Poisson's ratio was characterized. The results indicated that the size, shape and distribution of the pores in the hydrogel matrix had strong influence on the local Poisson's ratio, which varying from positive to negative at micro-scale. The size-dependency of their local Poisson's ratio reflected and quantified the uniformity and heterogeneity of the micro-porous structures in the PVA hydrogels.
许多描述通用泡沫或负泊松比材料变形的模型都是基于材料内部均匀和有序的假设。然而，非均匀异质性往往是许多多孔材料和复合材料的固有特性，但难以测量。在这项工作中，受负泊松比材料结构的启发，设计并加工了具有内凹孔（IICP）或互联孔（ICP）的多孔 PVA 水凝胶。测试了 PVA 水凝胶在压缩下的变形，并对其泊松比进行了表征。结果表明，水凝胶基体中孔的大小、形状和分布对局部泊松比有很强的影响，在微观尺度上从正变为负。它们局部泊松比的尺寸依赖性反映并量化了 PVA 水凝胶中微多孔结构的均匀性和异质性。
