Enhancing the Flame Retardancy of Nitrile Butyl Rubber using Polyoxometalates Modified by Functionalized Halloysite Nanotubes

Abstract

NBR is extensively used in various applications such as automotive, seals and gaskets, cable insulation and protective gloves etc. However, its high flammability limits its application in many fields. Nano-clays hold a significant position among the nano flame retardant filler in the domain of polymer composites due to high surface to volume ratio that required less amounts of nano-clay to obtain require properties. They possess a potential to increase the flame retardant, thermal durability as well as improve their mechanical strength of polymers. Halloysite nanotubes (HNTs) are naturally biodegradable flame retardant material. Halloysite nanotubes (HNTs) possess a nanotubular structure within the context of 1:1 clay. HNTs show inadequate dispersibility and weak interfacial interaction when integrated with polymers. To solve this problem, silane treatment was introduced which used 3- aminopropyltriethoxysilane (APTES), formed functionalized halloysites nanotubes (fHNTs) and subsequently utilized as a substrate to immobilize H4SiW12O40. The final nanofiller was prepared which confirmed by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Different rubber nanocomposites samples NBR-0 ,NBR-1, NBR-3, NBR-5, NBR -7, NBR- 7HNTs, NBR-7POMs and NBR-10 were prepared by varying amount of nanofiller into NBR via melt blending in an internal mixer. The structural and morphological characteristics of these composites were analyzed by using SEM , FTIR , Raman spectroscopy and XRD. The mechanical property was characterized by using universal testing machine (UTM) and flame retardant property was evaluated by using UL-94, NBR-10 falls under the category of V-2 due char formation and gas particle which delay fire ignition phenomenon.