Creaming of skim natural rubber latex with chitosan derivatives

Abstract

To recover residual rubber from skim natural rubber (SNR) latex, a novel method was developed on the basis of the use of water-soluble chitosan derivatives. An anionic chitosan derivative, N,O-carboxymethyl chitosan (CMCh), and a cationic chitosan derivative, N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTACh), were prepared. It was found that the creaming process could be achieved with both chitosan derivatives. By the addition of 7.34-10.3-g/L CMCh, SNR latex was almost completely creamed, and no coagulation of SNR particles in the cream phase occurred. In the case of HTACh, the creaming process was achieved with a lower concentration (<3.70 g/L) than in the case of CMCh, but the size of SNR particles in the cream phase was larger. Solid-state 13C-NMR, thermogravimetric analysis, and f potential measurement results provided evidence that the creaming of SNR latex with CMCh and HTACh was controlled by the depletion flocculation and adsorption mechanisms, respectively. © 2009 Wiley Periodicals, Inc.