Comparative rheology and microstructure analysis of natural rubber latex with conventional and eco-friendly preservatives.

This article investigates how different preservation methods—traditional ammoniated versus two ammonia-free eco-friendly preservatives developed by AFLatex Technologies—affect the microstructure and rheological properties of natural rubber latex (NRL). Using rheological modeling with the Cross and extended Krieger–Dougherty (K&D) models, alongside Taylor–Couette flow simulations, the study identifies distinct critical volume fractions for viscosity changes: approximately 0.6–0.7 for ammoniated latex and 0.4–0.55 for ammonia-free systems. The findings suggest that ammonia-free preservatives form protective layers around latex particles, influencing particle interactions and shear-thinning behavior differently than ammoniated systems, which undergo surfactant hydrolysis. Simulations reveal shear-induced particle migration toward low-shear regions, corroborating experimental observations of localized particle concentration increases that impact viscosity. This research provides insights into how preservation chemistry modulates NRL's microstructure and flow behavior, relevant for industrial applications requiring precise control of latex stability and processing.