Ultimate elongation of polymer gels with controlled network structure

Tetra-PEG gel, which is a polymer gel with a well-controlled network structure, was utilized to examine the model predicting the ultimate elongation ratio of elastomeric materials, i.e., the Kuhn model. The effect of polymer fraction, degree of polymerization of network strands, and connectivity of the Tetra-PEG gel was discussed. The ultimate elongation ratio was estimated from the stress-elongation curves using the extended Gent model. The ultimate elongation ratio of the Tetra-PEG gels with different structural parameters did not obey the Kuhn model at all. Instead, we proposed a new semi-empirical model predicting the ultimate elongation ratio of Tetra-PEG gel.