|Non-Affine Deformation of Rubber and Single Polymer Chain Deformation
Department of Organic and Polymeric Materials, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo, Japan
Nippon Gomu Kyokaishi,(2006),79(10),466-471 General Review in Japanese
Two parts of the physics of rubber elasticity have not been fully verified experimentally to date. The first one is the entropic elasticity of a single polymer chain. The second one is Affine deformation hypothesis, the bridge between molecular bases of rubber elasticity and phenomenological deformation mechanics of polymer chain network. Atomic force microscopy (AFM) was employed to find a cue to experimental evidence for them. Therefore, we did not give much attention to AFM's high-resolution feature, while its nanometer-scale palpatbility was specially utilized instead. The technique, so-called, nanofishing revealed the entropic elasticity of a single polystyrene chain in good, or theta solvent conditions. The entanglement inside a single polymer chain was detected by nanometer-scale stress-relaxation experiment with quick stepwise strain excitation. The breakdown of Affine deformation was also observed in uniaxially elongated natural rubber vulcanizate, which showed a very wide modulus distribution. We concluded tentatively that the plateau region observed in macroscopic stress-strain curve could be attributed to the remaining of the local region that had sufficiently low modulus even after stretched at the elongation ratio of around 4.
Entropic Elasticity, Affine Deformation, Atomic Force Microscopy, Nanofishing, Natural Rubber, Plateau Region