Polyesteramidesulfone as novel reinforcement and antioxidant nanofiller for NBR blended with reclaimed natural rubber

Abstract

Abstract In this study, we exploited the addition of reclaimed natural rubber waste (NRr) in acrylonitrile butadiene rubber (NBR) to develop a cost-effective rubber blend based on 92 phr NBR and 8 phr NRr. The mechanical properties of the blend were enhanced by using new reinforcement nanofiller synthesized by condensation reaction between terephthaloyl chloride (TPC) with bis(4-aminophenyl) sulfone (BAPS) and bisphenol S. Polyesteramidesulfone (PEAS) was produced and well characterized using different analytical tools such as; FTIR, H NMR, DSC, TGA, TEM, and GPC. The TEM image of PEAS showed nano irregular-shaped particles. PEAS was mixed with NBR and NBR/NRr blend in different loading levels, (1.5, 3 and 6 pphr) to prepare NBR/PEAS and NBR/NRr/PEAS vulcanizates. The tensile strength, elongation at break, equilibrium swelling, crosslinking density, thermo-oxidative aging test, FTIR, TGA, and SEM of the rubber vulcanizates were measured. Fractured morphology was detected in SEM images by the partial replacement of NBR with NRr leading to a decrease in the tensile strength and elongation at break of NBR/NRr vulcanizate than neat NBR. However, the addition of PEAS improved the compatibility between NBR and NRr and increased the cross-linked structure of NBR chains through physical links leading to increase the tensile strength and decrease the elongation of the vulcanizates. The low molecular weight of NRr and the degradation of amide and ester groups of PEAS lowered the thermal stability of their vulcanizates up to 420 °C than neat NBR. Loading of PEAS in NBR and NBR/NRr caused an increase in their glass transition temperature. The rate of reduction in tensile strength up to 7 days is much lower in vulcanizates loaded with PEAS than those without. It was concluded that PEAS played dual function in NBR and rubber blends as an antioxidant and reinforcement nanofiller.