A special mechanical behavior of gels and its micro mechanism

It is found in experiment of gel specimen that the elastic modulus under te nsion can be 1.6 times of that under compression. In order to explain this phenomenon, a micro model that consists of network and water is proposed. I t is assumed that the macromolecular chains can only sustain tensile force but not compression along chains. Based on this constitutive model, the ela stic moduli of gels under tension, compression and shear are derived for sm all strain case. The irregular behavior of gels predicated by this model ar e consistent with the results of experiment.