Sintesis Dan Karakterisasi Komposit Termoplastik Berbasis Lignin Tergrafting Polistirena Dengan Metode Polimerisasi Radikal Transfer Atom

Abstract

This research examines the synthesis process and characterization of lignin-based thermoplastic composites grafted with polystyrene. This research was carried out to combine the two properties of lignin and polystyrene through chemical modification using atom transfer radical polymerization (ATRP). Lignin was isolated from empty oil palm fruit bunches (TKKS) with the Kraft method using H2SO4 5N. After the lig-nin was isolated, an acidification process was carried out using 2N HCl. Synthesis of the lignin-Br macroinitiator was carried out by reacting lignin with 2-bromoisobutyryl bromide at 0°C for 15 minutes continued with stirring at room tem-perature for 24 hours. Synthesis of lignin-g-polystyrene was carried out using a CuBr/PMDETA catalyst at a temperature of 100°C for 24 hours. The resulting lignin, lignin-Br and L-g-PS were characterized by FTIR, SEM, TGA and DSC. The FTIR results show that polystyrene has been grafted with lignin where there are wavenumber shifts in several functional groups which is supported by the FTIR spectrum at peaks 3059 and 3026 cm-1 which correspond to the stretching vibrations of the C-H groups on the benzene ring. Peaks at wavenumbers of 746 and 696 cm-1 indicate the presence of a single substituted aromatic core associated with polystyrene chains that have been grafted into lignin. SEM results show that the ATRP reaction has been successfully carried out with changes in morphology on the surface of L-g-PS which is more homogeneous and has a large surface. TGA results show that L-g-PS has a large change in thermal degradation temperature at temperatures between 293-437°C and its thermal stability tends to be stable at temperatures above 437°C and the residual weight of L-g-PS is 0.2%. The DSC results show that there has been a change in the Tg value where L-g-PS have Tg value of 142.78°C.