A new approach with prepregs for reinforcing nitrile rubber with phenolic and benzoxazine resins

Abstract

Acrylonitrile-co-butadiene rubbers (NBR) reinforced with phenolic and benzoxazine resins (NBR–Ph and NBR–Bz respectively) are prepared by a novel method using co-curing. The relative effect of these resin reinforcements with NBR in comparison to the non-reinforced NBR rubber compound NBR–S under the same conditions has been investigated. It was found that these resins exist in the form of a localized, interpenetrating network structure in the NBR matrix. For both NBR–Ph and NBR–Bz composites, the tensile strength, tear strength and elongation at break increases compared to NBR–S. The tensile strength in particular was increased by about 91% for NBR–Ph and by about 109% for NBR–Bz. Thermogravimetric analysis (TGA) provides evidence for the superior thermal stability for NBR composites over NBR–S. A decrease in the swelling values are observed in the NBR composites and the retained tensile strength, elongation at break and modulus from thermal aging studies are found to be superior than NBR–S. These results have shown that both the phenolic and benzoxazine resins are effective reinforcements for NBR materials.