Chemical surface modification of lignin particle and its application as filler in the polypropylene composites

•Pristine lignin was chemically modified by hydrolysis condensation reaction.•Polypropylene-graft-maleic anhydride was anchored onto the surface of lignin particle.•The PP composites with MAPP-a-Lignin showed the improved mechanical properties.•There was a stronger interaction between MAPP-a-Lignin and PP in the composites. The pristine lignin was chemically modified by hydrolysis condensation reaction using (3-aminopropyl) triethoxysilane and then was subsequently treated with polypropylene-graft-maleic anhydride to give MAPP anchored lignin (MAPP-a-Lignin). The modified lignin particles prepared at each steps were characterized by FT-IR, SEM-EDX and XPS measurements. Polypropylene composites with MAPP-a-Lignin were prepared through melt-blending method. In this work, the effects of content of MAPP-a-Lignin on the properties of the polypropylene composites were investigated. From the results of mechanical properties, melting/crystallization behaviors and the morphologies of the composites, it was found that there was a stronger interfacial interaction between MAPP-a-Lignin and polypropylene in the composites.