Still current challenge for rubber technology : Find new criteria for the prediction of manufacturing behaviour of natural rubber

Vaysse Laurent, Sainte-Beuve Jérôme, Bonfils Frédéric. 2003. Still current challenge for rubber technology : Find new criteria for the prediction of manufacturing behaviour of natural rubber. In : IRRDB annual meeting, Challenge for natural rubber in globalisation, 15 - 16 September, Chiang Mai, Thailand. s.l. : s.n., 14 p. IRRDB Annual Meeting, Chiang Mai, Thaïlande, 15 Septembre 2003/16 Septembre 2003.

Résumé : From more than one hundred years to now, natural rubber (NR) has been described as an enigmatic, rare and expensive material. Automobile industry, which owes a lot to NR (and vice versa), has promoted its production (7 millions metric tons in 2002). This agro-material with specific properties, still unequalled until now for technical items manufacturing, presents a handicap for users: its lack of consistency. Indeed, with automation of manufacturing processing, industrials seek raw natural rubber with constant quality from one lot to another such as it is for synthetic rubbers. It is thus crucial to be able to produce constant quality natural raw rubber - which is not the case today - by identifying new physicochemical criteria more pertinent than the currently used ones. Actually, national (STR, SMR, SIR, ...) or international (ISO 2000) standards which were created for this purpose are useful but not sufficient to characterise precisely enough the technological properties of raw NR. This concern, more often raised by north manufacturers, may also become a reality for manufacturers from NR-producing countries. Moreover, the synthetic rival of NR could be strengthened if the announced 2005 shortage of NR occurs in the elastomer market. Thus a main challenge for natural rubber technologists remains to improve the prediction of NR manufacturing behaviour. In this paper, a strategy, based on the relationship between structure of NR and manufacturing behaviour, is proposed in order to find new criteria more relevant to predict NR behaviour. It has to be performed from initial stages (from tapped tree to manufacturer's mixer) to downstream (product behaviour and variation during the manufacturing (blending, shaping, vulcanisation)). Indeed, to obtain applicable results; this approach should be as integrated as possible and thus should involve researchers (agronomists, technologists, biochemists, etc...) and industrial partners (raw rubber producers and end-used product manufacturers). The NR can be described through three structural levels: macrostructure (supramolecular scale), mesostructure (macromolecular scale) and microstructure (molecular scale). The study of relationship between these levels and between structures and manufacturing behaviour seems to be the best approach to define new prediction criteria. Some preliminary results (e.g. relation between Wallace Plasticity (Po, macrostructure) and weight-average molar mass (Mw, mesostructure) or relation between z-average molar mass (Mz, mesostructure) and breakdown Index (manufacturing behaviour)) are shown. Details are also presented about the recently launched joint project in Thailand (Kasetsart University - RRIT - CIRAD) dealing with the relation between lipid composition (microstructure) and mixing properties (manufacturing behaviour) of natural rubber which is exactly in line with the previously described strategy.

Mots-clés Agrovoc : caoutchouc, propriété physicochimique, consistance, propriété rhéologique, technologie appropriée, qualité

Classification Agris : Q60 - Traitement des produits agricoles non alimentaires

Auteurs et affiliations

• Vaysse Laurent, CIRAD-CP-HEVEA (THA)
• Sainte-Beuve Jérôme, CIRAD-CP-HEVEA (FRA)
• Bonfils Frédéric, CIRAD-CP-HEVEA (FRA) ORCID: 0000-0001-7016-4770

Source : Cirad - Agritrop (https://agritrop.cirad.fr/525880/)

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