The main component of raw natural rubber is

cis

-1

4-polyisoprene (PI). To obtain better mechanical properties

raw natural rubber is usually vulcanized with sulfur to form a crosslinked network. To understand the relationship between the complicated network and the mechanical properties of vulcanized natural rubber (NR)

several statistical models have been proposed since the 1940s by the pioneers such as Flory. To make complicated problems simple

two major assumptions were adopted in the models. (1) Only PI chains are considered in the crosslinked network. However

polysulfide chains are not included in the models. (2) Only the entropic elasticity of the network chains is taken into account

but the enthalpic elasticity (arising from variation of bond lengths and angles at large deformation) is ignored. As a result

there are several limitations in the traditional models. First

the traditional models fail to predict the elasticity of NR under large deformation. Second

the effects of sulfur content cannot be explained satisfyingly. To solve the above problems

Shuxun Cui and coworkers have made two modifications to the traditional models. First

the sulfur content is considered in the model. Second

the single-chain elasticities (which include both entropic and enthalpic elasticities) of the two main components of NR (PI and polysulfide) are integrated into the model. They found that the new model (called TCQMG model) is clearly superior to the traditional models (

e.g.

Gaussian model) in describing the mechanical properties of NR

especially for large deformation. In addition

the effect of sulfur content on the mechanical properties of NR can be explained well. Considering the similarity in network structures between NR and other vulcanized rubbers

it is

expected that with more data of single-chain mechanics

this model may be used as a general model for various rubbers. With minor modifications

it is anticipated that the model could be applied in the field of supramolecular hydrogels.