Grafting of poly(vinyl alcohol) on natural rubber latex particles

Abstract

Poly(vinyl alcohol) (PVA) was grafted on natural rubber (NR) latex particles (NR-g-PVA) using potassium persulfate to generate active radicals on both NR particle surface as well as PVA molecules. 1H- and 13C-nuclear magnetic resonance spectroscopy suggested a possibly chemical attachment of PVA on the NR. The amount of graft-PVA expressed in term of grafting percentage (%G) increased almost linearly with the amount of PVA adding to the NR latex. Measuring by dynamic light scattering, the particle size of NR-g-PVA particles was larger than the size of unmodified NR, also it increased with the molecular weight and %G of PVA. Transmission electron microscopy images of the NR-g-PVA latex particles revealed that the size of PVA-grafted NR particle was enlarged by a layer of graft-PVA surrounding the NR particle. Given by the graft-PVA layer surrounding NR particles, the NR-g-PVA latex particles possessed better colloidal stability as lowering pH compared with the unmodified NR latex. Comparing with unmodified NR particles, the electrophoretic mobility of NR-g-PVA particles was lower due to the presence of graft-PVA that shifted the shear plane further away from the surface of the particles. Copyright © 2012 Wiley Periodicals, Inc.