Localized Yielding Around Crack Tips of Double-Network Gels
Localized Yielding Around Crack Tips of Double-Network Gels
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DOI：
10.1002/marc.200800227
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发表时间：
2008-09
影响因子：
4.6
通讯作者：
Yoshimi Tanaka;Yasunori Kawauchi;T. Kurokawa;H. Furukawa;T. Okajima;J. Gong
中科院分区：
文献类型：
--
作者：
Yoshimi Tanaka;Yasunori Kawauchi;T. Kurokawa;H. Furukawa;T. Okajima;J. Gong
双网络（DN）凝胶是一种由刚性和柔性聚合物组分组成的互穿聚合物网络（IPN），具有两种突出的力学性能：拉伸试验中整个试样的屈服变形和撕裂试验中相当高的断裂能。在这项研究中，原子力显微镜（AFM）的测量进行DN凝胶，以确定立即低于断裂表面EF和低于通常的成型表面EM的局部杨氏模量，并比较局部模量与体积杨氏模量测量之前和之后的屈服变形，表示为E h和Eg，分别。Em和Eh在0.1MPa左右，Ef和Es在0.01MPa左右，比前两个模量低一个数量级。有序关系表明，DN凝胶在断裂过程中，在裂纹尖端附近发生了局部屈服变形。这支持了最近提出的解释DN凝胶高断裂能的唯象模型的基本假设。（H. R. Brown，Macromolecules 2007，40，3815-3818; Y.田中，欧罗巴。Lett. 2007，78，56005）。
Double-network (DN) gels, a type of interpenetrating polymer network (IPN) consisting of rigid and flexible polymer components, exhibit two outstanding mechanical behaviors: yielding deformation of the entire specimen in tensile tests and quite high fracture energy in tearing tests. In this study, atomic force microscope (AFM) measurements were conducted on DN gels to determine the local Young's moduli immediately below the fracture surfaces E f and below the usual molded surfaces E m , and compare the local modulus with bulk Young's moduli measured before and after the yielding deformation, denoted as E h and Eg, respectively. E m and E h are around 0.1 MPa; E f and E s , around 0.01 MPa, one order lower than the former two moduli. The order relation indicates that yielding deformation occurred locally around the crack tip of the DN gel during fracture. This supports the basic assumption of phenomenological models recently proposed to explain high fracture energy of DN gels. (H. R. Brown, Macromolecules 2007, 40, 3815-3818; Y. Tanaka, Europhys. Lett. 2007, 78, 56005).