Quantitative determination of palm-based polymeric surfactants in natural rubber latex using conductivity and complementary analytical techniques

Abstract

This work is the first attempt to establish a practical quantification protocol for novel palm-based polymeric surfactants AS1, AS2, and AS3. The method is optimised for natural rubber latex (NRL), not aqueous media. Conductivity is proposed as a novel application for field detection, not as a new analytical principle. Other analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), zeta potential analysis, thermogravimetric analysis (TGA), conductivity measurement, and contact angle measurements were also explored as the qualitative and quantification methods for novel palm-based polymeric surfactants in NRL. Among these methods, conductivity measurement shows the greatest promise for both qualitative and quantitative determination of AS1, AS2, and AS3 in latex. These surfactants exhibit characteristic anionic electrical conductivity, with a strong linear relationship observed between conductivity and surfactant concentration (R² >0.99). Contact angle measurements provided insights into the surfactant characteristics, including hydrophilic properties and surface absorption behaviour; however, they may not be suitable for quantification, as the data show a polynomial relationship with a poor fit (R² < 0.99). Zeta potential analysis indicated consistent colloidal stability across all samples, which displayed consistent − 30 to -50 mV. FTIR analysis offered valuable qualitative insights, particularly for functional group identification, while TGA analysis assessed thermal stability and degradation. Although FTIR, zeta potential, and TGA analyses are effective for characterising the impact of the surfactants on latex properties, they may not be suitable for quantification purposes. All methods exhibited some detection limitations, highlighting the need for further refinement and exploration to enhance their reliability and accuracy.