Small-molecule modification of natural rubber latex: A step toward sustainable and compostable rubber products

Natural rubber latex (NRL), derived from Hevea brasiliensis, is a renewable material widely used in numerous industries due to its excellent elasticity and film-forming properties. However, elastomers obtained from vulcanized NRL tend to resist biodegradation, which, especially in disposable products like i.e. balloons, poses environmental concerns. Therefore, developing strategies to enhance NRL biodegradability without compromising its functional performance is of increasing importance. This study presents the novel approach for NRL functionalization by using small-molecule additives: sorbitol, urea, and glycerol monostearate (each at 1 phr) to improve its compostability, while maintaining mechanical and application properties. The modified and unmodified latex films were subjected to degradation in simulated home composting conditions, and changes in mass, surface morphology, mechanical properties, and thermal stability throughout the composting process were analyzed using scanning electron microscopy (SEM), tensile testing, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). Additionally, the microbial biodiversity in composting matter used for unmodified and modified latex degradation was analyzed. Among the tested additives, sorbitol demonstrated the most promising performance, yielding a homogenous material structure, maintaining tensile strength prior to composting, and significantly accelerating biodegradation in first weeks, evidenced by a substantial decrease in tensile strength and high mass loss. These findings suggest a viable pathway sufficient for large scale production of biodegradable NRL-based products with minimal loss in performance.