Evaluating performance of traditional and eco-friendly latex preservatives

Rubber latex is widespread, used in everything from party balloons to medical equipment. As a natural product, latex needs to be treated with preservatives to keep it stable. Typically, these preservatives contain ammonia — which, though effective, can pose health risks.

Dibisa et al. compared a conventional latex preservative with two alternative, eco-friendly and healthier preservatives developed by AFLatex Technologies. They used analytical and computational modeling to evaluate the resulting rheology and microstructure of the latex with the goal of assessing its performance and stability.

The authors employed two analytical models to capture the non-linearity of latex viscosity and to describe viscosity as a function of volume fraction. They used a computational method to validate the results of these models and adjust the physical properties of different latex sources and treatments.

“Accurate viscosity predictions are crucial for guiding formulations and ensuring reliable performance in downstream applications, yet the fundamental properties of this newer latex system were not well understood,” said author Oliyad Dibisa.

Using this approach, the researchers calculated a critical packing density of around 0.5 to 0.6 for ammonia-free latex and about 0.7 for ammoniated latex, above which the samples experience significant alterations to their rheological properties, transitioning into a more solid-like state. This results in increased viscosity and shear thinning compared with traditional preservatives.

“Performance-wise, these differences impact shelf life and mechanical stability. Eco-friendly preservatives maintain structural integrity for over five years, whereas ammoniated latex typically degrades within six months,” said Dibisa.

The authors plan to experimentally study the interactions between latex and ammonia-free preservatives to better understand the mechanisms governing this improved performance.

Source: “Comparative rheology and microstructure analysis of natural rubber latex with conventional and eco-friendly preservatives,” by Oliyad T. Dibisa, Héctor A. Arroyave, Allen Jonathan Román, Julio C. Rodriguez, and Tim A. Osswald, Physics of Fluids (2025). The article can be accessed at https://doi.org/10.1063/5.0255679 .

This paper is part of the R. B. Bird International Polymer Colloquium Collection, learn more here .