ENR-50 Compatibilized Natural Rubber/Recycled Acrylonitrile-Butadiene Rubber Blends

Abstract

Epoxidized natural rubber has been used as a compatibilizer for natural rubber-recycled acrylonitrile-butadiene rubber (NR/NBRr) blends, vulcanized by sulfur.NBR gloves have excellent resistance to punctures, tear and many types of chemicals, while NR has good physical and mechanical properties.Incorporation of ENR-50 into the rubber blends has improved processability, stiffness, resilience and excellent oil resistance.NR/NBRr blends were prepared by two-roll mill with five different compositions with the ENR-50 content fixed at 10 phr.Cure characteristics, mechanical properties and morphology (SEM) studies were performed to determine the compatibility of NR/NBRr blends in the presence of ENR-50.The cure characteristics showed that NR/NBRr blends with the presence of ENR-50 have lower scorch time (t s2 ) and cure time (t 90 ) than NR/NBRr blends without ENR-50.However, the NR/NBRr blends with ENR-50 exhibited higher minimum torque (M L ) and maximum torque (M H ) which indicated difficult processability of the blends after compatibilization.Incorporation of ENR-50 into NR/NBRr blends improved all the tensile properties (tensile strength, tensile modulus and elongation at break) compared with NR/NBRr blends without ENR-50.The improvement in hardness upon compatibilization is due to an increase in crosslink density.Scanning electron microscopy (SEM images) of the fracture surfaces indicates that, with the addition of ENR-50 in NR/NBRr blends, better adhesion between NR and NBRr was obtained, thus improving the compatibility of NR/NBRr blends.