Castor-oil based polyurethane/NiCo-OLDH nanocomposites with improved flame retardant properties

Abstract

Polymer nanocomposites are known for improved thermal properties, mechanical properties, gas permeability and flame retardant properties compare to neat polymer matrix or conventional composites. Polymer matrix nanocomposites are widely used in defense use, equipment, automobiles and aircraft components, housings, packaging, coating applications. The present work aims to prepare polymer matrix nanocomposites to improve the flame retardant properties of a matrix where reinforcement is flame retardant in nature. The castor-oil based polyurethane has been synthesized by reacting castor-oil and isophorone diisocyanate which is flammable. It is very important to mention that inorganic nanofillers i.e. layered double hydroxides have been used as a reinforcement in castor-oil based polyurethane to increase the flame retardant, thermal and mechanical properties of nanocomposites. In this study, nickel–cobalt organomodified layered double hydroxide (NiCo-OLDH) has been prepared by the co-precipitation method. The prepared NiCo-OLDH has been characterized by various techniques. The average particle size of the OLDH nanoparticles is 68 nm as analyzed by particle size analyzer. The morphology of the OLDHs are in fibril form as shown in transition electron microscopy (TEM). The different weight percentages of NiCo-OLDH (1.5–5%) have been incorporated into synthesized castor oil based polyurethane (COBPU) to prepare COBPU/NiCo-OLDH nanocomposites using solvent blending method and characterized by FTIR, XRD, SEM, TGA techniques. FTIR has been used to confirm the functional group and metal oxide present in the nanocomposites. COBPU/NiCo-OLDH nanocomposites have shown a 10 % improvement in thermal stability and an increased in tensile strength of 26% as compared to neat COBPU. Flame retardancy as measured by LOI of the nanocomposites are in the range of 23–28%.