Acid-induced aggregation and gelation of natural rubber latex particles

Guilherme de Oliveira Reis (1) , Paul Menut (1) , Frédéric Bonfils (1) , Laurent Vaysse (1) , Yacine Hemar (2) , Christian Sanchez (1)

1 UMR IATE - Ingénierie des Agro-polymères et Technologies Émergentes
2 School of Chemical Sciences

Coagulation of natural rubber latex suspensions into an elastic gel is the first step of their processing into rubber. We studied this transition under controlled acidification conditions with the aim of identifying the main parameters controlling gel formation. The onset of aggregation and the percolation events observed during continuous acidification were monitored on a large range of volume fractions by a combination of light-scattering techniques adapted to the different degrees of suspension opacity (namely, diffusing wave spectroscopy, static light scattering and turbidimetry) and by rheology. We consequently established the state diagram of NRL particles in the pH–ϕv space during acidification. Within this diagram, we identified three states: a suspension, a two-phase macroscopically separated system in between a gel and a suspension, and a gel. The rheological properties of the gels were characterized as a function of the volume fraction ϕv. The elastic modulus scale with ϕv3.35, it shows remarkable consistency independently of the acidification kinetics and final pH.

Mots clés: Natural rubber latex; Electrophoretic mobility; Gelation time; Colloidal gel; Irreversible aggregation; Core–shell particles

Domaines: Chimie-Physique [physics.chem-ph]

Guilherme de Oliveira Reis, Paul Menut, Frédéric Bonfils, Laurent Vaysse, Yacine Hemar, et al.. Acid-induced aggregation and gelation of natural rubber latex particles. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015, 482, pp.9-17. ⟨10.1016/j.colsurfa.2015.04.015⟩. ⟨hal-01269379⟩