Investigation on the mechanical and ageing properties of acrylic rubber reinforced halloysite nanotubes/carbon black hybrid composites

In the present research, acrylic rubber (ACM) composites containing Carbon black (CB) of 70 phr alone and five different ACM hybrid nanocomposites containing a fixed content of CB (60 phr) and varied content of halloysite nanotubes (HNT) (2, 4, 6, 8 and 10 phr) were prepared by melt-blending on a open twin roll mill. The prepared composites were examined for their microstructure, physical and mechanical properties, hot air and hot oil ageing resistance. Studies revealed that addition of HNT in CB filled ACM composites resulted in superior mechanical properties, improved swelling resistance and augmented impedance to oxidation and hot oil compared to ACM containing CB alone. Further ACM composites with 6 phr of HNT demonstrated an enhancement of 31.49%, 16.15%, 39.65%, 6.39% and 28.06% respectively in stress at break, % elongation at rupture, modulus at 100% elongation, resistance to crack propagation and solvent uptake. Further the same sample exhibited retention of stress at break and elongation at rupture of 99% and 92%, 98% and 89%, 94% and 96% respectively in hot air, in IRM 901 oil and in IRM 903 oil respectively. Studies on the microstructure revealed the formation of HNT-ACM-CB intercalated structures. Fourier transform infrared spectroscopy studies confirmed the establishment of bonding of hydrogen amidst the tubular nanofiller and the ACM rubber. Field emission scanning electron microscopy studies divulged the intercalation of tubular filler by ACM rubber, black filler and curing constituents and development of local HNT-CB network. These studies prove that partial replacement of traditional CB filler with tubular HNT is a promising approach to produce ACM composites with superior mechanical, thermo-oxidative ageing and hot oil ageing properties.