Structure and Properties of Natural Rubber

Abstract

Natural rubber is a naturally occurring nano-composite, which possesses a complicated hierarchal structure. A primary structure of natural rubber is ω'-(trans)₂-(cis)_n-α' : that is, modified dimethylallyl group, 2 trans-1,4-isoprene units, about 5,000 cis-1,4-isoprene units and modified prenol group, aligned in this order. The ω'-terminal unit and α'-terminal unit may be attracted to proteins and phospholipids through strong attractive forces, which are comparable to attractive forces in chemical bonds; so that, three dimensional network structure of natural rubber is formed with the proteins and phospholipids to generate gel fractions. The proteins and phospholipids are incorporated into the nanomatrix structure, in which natural rubber particles with an average diameter of 1 μm are dispersed in matrix of non-rubber components such as the proteins and phospholipids. The hierarchal structure realizes not only entropy elasticity but also energy elasticity. It creates new science and technology of rubber and opens new criteria of molecular and materials designs.