Experimental studies on mechanical properties of natural rubber carbon black-carbon nanotube composite

In the present work, Natural rubber (NR) conventional composite containing 20phr black filler (CB) is taken for study. In order to reduce the utilization of CB, new hybrid nanocomposites containing a fixed content of 10phr CB and varied content of COOH functionalized multi-walled carbon nanotubes (CNT) (1phr-4phr) were developed by melt-blending on a twin roll mill and their morphology and mechanical properties were tested and compared with conventional composite. The prepared composites were examined for their morphology and various -mechanical properties. Studies revealed that incorporation of CNT in NR matrix resulted in superior mechanical properties in comparison to NR composites containing CB alone. Further NR hybrid nanocomposites containing 10phr of CB and 2phr of CNT exhibited an improvement of 15%, 10% and 3% in stress at break, elongation at rupture and resistance to crack propagation in comparison to the conventional composite containing 20phr CB. The same composite also exhibits superior hardness. The better performance of NR hybrid nanocomposites can be mainly attributed to high aspect ratio of functionalized CNT and its enhanced interactions with the NR matrix, enhanced CB-CNT interactions, improved dispersion of CNT in the elastomeric matrix due the existence of COOH group on the surface of CNT layers and formation of more cross-links between rubber and fillers with increase in nanofiller content. FESEM studies reveal the homogenous dispersion of hybrid fillers in the elastomeric matrix upto 2phr of CNT. These studies prove that partial replacement of CB with CNT is a promising approach to produce NR composites with superior mechanical properties. (C) 2020 The Authors. Published by Elsevier Ltd.