Amazon Rubber, A Potential Yet to be Rediscovered

Abstract

Natural rubber still has socioeconomic, environmental and technical importance, despite the production of several synthetic similar polymers in the last 70 years. The Amazon Rainforest, the genetic base of Hevea brasiliensis, harbors a great diversity of ecosystems that can result in differentiated latex and elastomer molecules, from trees of the same species or other species and varieties of laticifer plants. Even so, there is little research to compare latex and rubber properties produced from native trees and planted clones. In this work, rubber latex was collected from four locations in the Amazon, including the historical places of Boim and Belterra and the most cultivated clone in Brazil, the RRIM 600, from a hevea plantation in the Center-West of Brazil. The following colloid properties were determined: pH, viscosity, particle size, dry rubber content, total solids content, gel content, total lipids, and total proteins. The molecular weight and the main physical and mechanical properties of the rubbers were also determined. Some main results can be highlighted: the rubber sample from Acre, in the extreme Western part of the Amazon, presented the highest molecular weight, while the Belterra sample, from remaining plantations of the Ford Project in Amazon, showed the highest values for mechanical properties. On the other hand, the technical characteristics of the RRIM 600 clone are close to the results obtained for the Boim sample, in Para, of the micro-region from where Henry Wickham collected the 70,000 seeds in 1876, from which the species was internationally domesticated. The present work is one of the very few studies to have been carried out with latex and rubber of these ancient rubber trees.