Study on stability and kinetics of coagulation of nanoparticles in carboxylic acid- functionalized XNBR latexes

In the present work,emulsifier free carboxylated Acrylonitrile Butadiene rubber latexes(XNBR) stablized by carboxylic groups were synthesized by batch emulsion polymerization.The effect of carboxylic monomer type(Acrylic acid and Methacrylic acid) and their amount on the stability of the latexes were studied. Kinetics of coagulation was investigated by turbidity measurements and subsequently the stability parameters were obtained from this technique.Conductometric titrations were carried out to study the partitioning of carboxylic monomers between the phases.Results indicated that the higher the carboxylic monomer amount,the higher the stability of the latexes.(except the sample prepared with 3gr Acrylicacid).It was also observed that the AA monomers lead more carboxylix groups at the surface of the particles due to their higher hydrophilicity.In the case of 3gr AA, the hydrophilic nature of AA leads to more water soluble polymers in the aqueos phase and thus bridging mechanism occures and makes the particles coagulate into larg flucculates.

Keywords:

Carboxylated latexes-emulsifier free-XNBR-stability-coagulation