Cirad develops quality test for NR based on gel content

Montpelier, France - A team of researchers at CIRAD, the French agricultural research centre, has just used an innovative technique to identify a new indicator of the quality for natural rubber.

Natural rubber differs from its synthetic counterparts through its more complex structure. When it is dissolved in a conventional solvent, some of the natural rubber remains insoluble. This fraction is commonly referred to as the gel phase, or as a macrogel. The soluble fraction also contains rubber macromolecules and a variable quantity of microaggregates that make up a microgel. This has never before been adequately separated,

Gel has a major impact on the rheological properties of the material, and thus very probably on mixing and processing performance. CIRAD has thus studied various aspects of its macromolecular structure (links with rheological properties, gel formation mechanisms, etc).

To date, only macrogel has been quantifiable, but researchers are now also studying microgel. To this end, they have developed a methodology based on the size exclusion chromatography (SEC) technique. The solution containing the microgel is filtered and then centrifuged. This makes it possible to analyse macromolecular structure of and quantify the microgel.

By providing a more comprehensive characterization of natural rubber structure, this research has opened the way for a clearer understanding of the links between that structure and the properties of the end product. This should result in the emergence of new, more relevant quality indicators than the criteria currently used.

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Press releasefrom Cirad