Optimization Study of a High-Efficiency Preservative for Ammonia-Free Concentrated Natural Rubber Latex

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Chemistry

Background:

• Ammonia is a common preservative in concentrated natural rubber latex (CNRL) but poses health and environmental risks.
• Developing ammonia-free alternatives is crucial for safer and more sustainable latex production.

Purpose of the Study:

• To investigate thioacetamide derivative (TD) as a preservative for ammonia-free CNRL.
• To optimize a stabilization system using potassium hydroxide (KOH), lauric acid (LA), and sodium dodecyl sulfate (SDS) for enhanced preservation.

Main Methods:

• Systematic investigation of TD dosage and its impact on CNRL stability metrics.
• Optimization of KOH, LA, and SDS concentrations to complement TD's preservative effects.
• Evaluation of CNRL properties including viscosity, volatile fatty acid (VFA) number, mechanical stability time (MST), and mechanical properties of dry films.

Main Results:

• Optimal TD dosage (0.02-0.03%) effectively stabilizes CNRL, inhibiting VFA increase and improving MST.
• KOH regulates pH and enhances mechanical properties but excessive use thickens latex.
• LA improves MST and processability; SDS rapidly enhances MST and reduces viscosity, though it can affect dry film surface molding.

Conclusions:

• Appropriate dosages of KOH, LA, and SDS act synergistically with TD for ammonia-free CNRL preparation.
• Optimal TD dosage is 0.02-0.03%, KOH 0.1-0.15%, and LA 0.06-0.1% for maximum efficacy and desired properties.