Structure of Natural Rubber

Abstract

Natural rubber, obtained from Hevea brasiliensis, consists of'-terminal, two trans-1,4-isoprene units, long sequence of cis-1,4-isoprene units and'-terminal ('-(trans)2-(cis)n-'), in this order, in which the' and' termi-nals represent unknown terminal groups attracted with proteins and phospholipids. The' and' terminals are ana-lyzed in relation to structures of polyprenols such as (CH3)2C=CHCH2-(trans)2-(cis)n-OH and (CH3)2C=CHCH2-(trans)3-(cis)n-OH. The' and' terminals are found to play an important role in a formation of three dimensional networks of natural rubber, i.e. branching and crosslinking; the higher the molecular weight, the larger is the number of branching points. The formation of three dimensional networks is concerned with a biosynthesis of natural rubber on a surface of a rubber particle in latex stage.