Preparation and characterization of natural rubber latex modified starch blends

Natural rubber latex uses as a binder in coir foam industry. Starch has binding property and it also uses as a binder. The use of natural rubber latex- starch blends is an interesting research area due to the low cost and environmental friendliness of starch. Starch has been incorporated into latex and phase separation of latex and starch particles is the major drawback. The objective of the present study is to reduce phase separation of starch-latex blend by modifying the chemical structure of starch. In this study, tapioca starch was used and its structure was modified using sodium hydroxide and benzyl chloride and starch ester was prepared. FULK spectroscopic analysis was used to characterize the modified starch structure. Un-modified starch and modified starch, un-vulcanized latex and vulcanized latex were used to prepare blends with different degree of substitutions. Viscosities of each blend were measured. Mechanical properties of films prepared using blends were obtained. Phase separation was observed for un-modified starch-latex blends. Phase separation of natural rubber latex and starch was eliminated by using the modified starch. The addition of tapioca starch into natural rubber latex matrix was found to reduce tensile strength (39.87%) and ultimate elongation (28.04%) of new blends at their optimum level of blend properties