Factors affecting creaming efficiency of bio-based polymers, vulcanization and mechanical properties of creamed skim rubber

Recovery of skim rubber from skim natural rubber (SNR) latex was studied by using three bio-based polymers, N,O-carboxymethyl chitosan (CMCh), sodium alginate (SA) and carboxymethylcellulose (CMC), as creaming agents. It was observed that creaming efficiency of the bio-based polymers was governed by concentration, viscosity and types of bio-based polymers used but independent of ammonia concentration and dry rubber content of SNR latex. CMCh, SA, and CMC having viscosity in a range of 10 mPa s – 25 mPa s were found to be the excellent creaming agents for SNR latex. Average sizes of rubber particles in the cream phase were not quite different from those of the original SNR latex. The skim rubber in the cream phase could be coagulated by using only a small amount of H2SO4. The obtained skim rubber contained lower protein than the skim rubber recovered by the traditional method using conc. H2SO4 which markedly affected the vulcanization characteristics of the skim rubber. In addition, physical and mechanical properties such as initial Wallace plasticity, modulus at 100% strain, tensile strength and elongation at break of recovered skim rubber were influenced by the use of creaming agents.