Thermal Stability and Fire Retardant Studies of Polymeric Nanocomposites based on Layered Double Hydroxides

Abstract

Layered double hydroxide (LDH) has been used as nanofiller in different polymer industry and gained extra intention in 21th century due to substantially improved physical, electrical, mechanical and extraordinary flame retardant properties. LDH nanofiller have variable charge density, which allows various interactions with the host polymer matrices. In this study, MOF based LDH and MOF based CNTs/LDH nanocomposites were synthesized by using MOF and CNTs as precursor respectively, by co-precipitation method to improve flame retardant efficiency of polymer. Pristine LDH have limitations of toxicity, low limited oxygen index (LOI %), high peak heat release rate, and high loadings. Acidic modification of MWCNTs was synthesized by co-precipitation method with nitric acid (HNO3) and sulphuric acid (H2SO4). MOF based LDH and MOF based CNTs/LDH were confirmed by FTIR described peaks at at 2,927 cm-1, 1528 and 1048 cm-1 attributed to the vibration of aliphatic sp3 C–H, C = O and C–O respectively along with the broad peaks around 3000-3400 cm-1 of water molecules of LDH. Hollow dodecahedral structure of MOF based LDH and MOF based CNTs/LDH nanocomposites were confirmed by Scanning Electron Microscopy (SEM) represented greater surface active sites and synergistic effect for polymer. Thermal property of MOF based LDH and MOF based CNTs/LDH nanocomposites were confirmed by Thermo Gravimetric Analysis (TGA) which described initial weight loss at 137ºC attributed to the removal of water between the layers and maximum weight loss at above 450ºC due to nitrates and hydroxyl ions, significantly higher than pristine LDH. This work advances progress on the development of highly safe multifunctional polymeric nanocomposites for economical use and reduced life threat.