Impact of size and biochemical composition of rubber particles on their interfacial behavior using two Hevea brasiliensis genotypes

The interfacial behavior and properties of fluid films of both rubber particle (RP) fractions ( i.e. small rubber particles (SRP) and large rubber particles (LRP)) from Hevea brasiliensis latex depends on the clone, and more specifically on the RP biochemical composition. SRP and LRP fractions from two clones of Hevea brasiliensis (RRIM600 and PB235) were characterized: biochemical composition (protein, lipid, cis -1,4 polyisoprene chain), RP film formation kinetics at the air-liquid interface, organization of films and interfacial rheological properties. Both RP fractions from PB235 clone contain more lipids than the ones from RRIM600. Particle size influences all measured indicators in the same way for both clones: SRP adsorb faster, reach a higher surface pressure and display stronger viscoelastic response than LRP. SRP and LRP also show different organizations at various scales, as observed by Brewster angle and atomic force microscopies. For each RP fraction, the clone influences most indicators but with various tendencies. This study highlights the effect of the high lipid content of clone PB235, particularly neutral lipids, on film formation kinetics. The faster formation kinetics of films from clone PB235 is attributed to the saturation of the interface by lipids. SRP films from both clones have similar rheological responses with a strong viscous component, assigned to the complete destructuration of RP membrane and the spreading of the polymer chains. In contrast, LRP retain their individual particle topology thus limiting long-distance interactions at the interface.