Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2008
Publication Date: 1/1/2009
Citation: Malmonge, J.A., Camilo, E.C., Moreno, R.M., Mcmahan, C.M., Mattoso, L. 2009. Comparative study on the technological properties of latex and natural rubber from Hancornia speciosa Gomes and Hevea brasiliensis. Journal of Applied Polymer Science. 111:2986-2991. Interpretive Summary: The USDA’s Domestic Natural Rubber project has studied the biochemistry of rubber biosynthesis in different rubber-producing species with a focus on natural rubber from Parthenium argentatum, guayule, a woody desert shrub suitable for cultivation in some parts of the United States. However, interspecific comparisons have been invaluable in the elucidation of the molecular biology, biochemistry, and botany of natural rubber biosynthesis. Our Brazilian collaborators at Embrapa and at UNESP bring expertise in many aspects of rubber production by the Brazilian rubber tree, Hevea brasiliensis, the primary source of natural rubber in the world today. The collaborative study of H. braziliensis will therefore contribute to development of P. argentatum or other domestic rubber-producing species. In the example presented here we have learned two important facts. 1) Latex produced in lacticifers is not by its nature high in protein content, as had previously been thought, 2) Rubber particle chemistry suggests Hancornia is similar to guayule in that higher fatty acid content is needed to maintain particle integrity for low protein rubber-particles.
Technical Abstract: This work reports a systematic comparative study of the properties of natural lattices and rubbers extracted from Hancornia speciosa Gomes and Hevea brasiliensis [(Willd. ex Adr. de Juss.) Muell.-Arg.] (clone RRIM 600) trees from 11 collections in Brazil throughout 2004. Natural rubber latex particle sizes and distributions were quite similar with average diameter around 1µm. Molecular weight, Wallace plasticity and Mooney viscosity values were approximately the same for both rubbers. Fourier Transform Infrared spectroscopy peaks characteristic of natural rubber were observed for both Hancornia and Hevea. Differences in technological properties found included lower values for Hancornia dry rubber content, % ash, % nitrogen, and plasticity retention index (PRI), but higher % acetone extract. Interestingly, nitrogen and protein content were much lower in Hancornia which might thus find important applications in non-allergic rubber uses. This represents the first report of lacticifer-produced low protein natural rubber.