Mechanical Properties of Rigid Networks and Their Gels

3 Mechanical Properties of Rigid Networks and Their Gels 

The elastic properties of a network of Gaussian segments follows from Eqs. (31-34) with the shear modulus G being directly dependent on the number of elastically effective network segments v  

The number concentration v is obtained by dividing the density of the polymer, p, by the molecular weight of an average segment between branchpoints, M,. A parameter (1 — 2/f) was introduced into the theory of rubber elasticity [729, 730] reflecting the interconnectivity of the crosslink junctions, such that [731] 

The Poisson ratio of elastomeric networks is usually very close to 0.5. When it is taken to be 0.5, a relationship between G and the tensile (Young s) modulus, E, is defined by 

In the case of elastomeric networks where the segments obey Gaussian statistics, the moduli are directly dependent on the absolute temperature, T. From the knowledge of G or E, one may estimate or v. 

---