User login


You are here

molecular network of elastomer

What is the reason behind the nonlinearity in the stress-strain curve of elastomers(Molecular Level)


Lihua Jin's picture

The elasticity of elastomers is due to entropic effect. Without stress, a polymer chain likes to coil together and form a spheric shape to increase the entropy. When you stretch it, its configuration becomes an elliptical shape. With the further increase of the stress, you can stretch the chain to almost a strand, finally start to stretch the bond and reach a stretch limit. The stretch limit is decribed in some models of rubber elasticity, for example, Gent model. I think this is the molecular picture of rubber elasticity and where the nonlinearity comes from.

Definately you are right.But as we know that elastomers are in the forms of coils and we know that the degree of randomness is entropy.It means that with the increasing stress coil gets alligned and  entropy decreases up to a certain extent.But what happens exactly I dont know.If you have a paper then please mail me on this

Thanking You
RajKumar sahu
Phd Scholar
IIT Patna

Lihua Jin's picture

You may want to take a look at the following class website.

Bo Li's picture


 You may refer to the following papers which provide more information on the entropic elasticity of elastomer


1.Arruda, E. M. and Boyce, M. C., 1993, A three-dimensional model for the large sretch behavior of rubber elastic materials,, J. Mech. Phys. Solids, 41(2), pp. 389–412. 

2. Mary C. Boyce, Direct Comparison of the Gent and the Arruda-Boyce Constitutive Models of Rubber Elasticity Rubber Chem. Technol. 69, 781 (1996); doi:10.5254/1.3538401 (5 pages)


Bo Li
School of Mechanical Engineering
28 West Xianing Road
Xian Jiaotong University
Xian, Shaanxi, 710049

Why the stress value is decreasing in the case of loading where as it is incresing with respect to time int the stress-relaxation test(UNiaxial tensile test at molecular level)

Thanking You
RajKumar sahu
Phd Scholar
IIT Patna

Subscribe to Comments for "molecular network of elastomer"

Recent comments

More comments


Subscribe to Syndicate