Development of amino acid deep eutectic solvent (AADES) as a crosslinker for carboxylated nitrile butadiene rubber (XNBR)

Abstract. Carboxylated acrylonitrile butadiene rubber (XNBR) a high-performance synthetic nitrile rubber is gaining much demand due to enhance mechanical properties in many applications including rubber gloves. The common crosslinker for XNBR, namely sulfur and zinc oxide with presence of accelerator which pose risks of Type IV Allergic Contact Dermatitis (ACD) and environmental concerns. To overcome this problem, a new amino acid-based deep eutectic solvent (AADES) is proposed as a green and sustainable ionic crosslinking agent. The ionic crosslinking between AADES and XNBR demonstrates superior machanical and thermal properties, offering a viable alternative to conventional methods. Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance were used to identify key structures in both cured XNBR and AADES. Mechanical and thermal analyses were performed using Universal Tensile Test, Thermal Gravimetric Analysis, and Differential Scanning Calorimetry on cured XNBR and AADES samples. Notably, XNBR crosslinked with a 1:3 DES molar ratio showed the highest tensile strength of 4.84 MPa, while a 1:2 DES molar ratio resulted in the highest elongation at break of 120%. Cured XNBR exhibited increased thermal stability, indicating successful ionic crosslinking between L-lysine: Glycerol and XNBR matrices. This study underscores AADES's potential as a promising crosslinking agent in polymer development, offering enhanced performance and reduced environmental impact.