The effect of hexamethylene diisocyanate modified ALCELL lignin as a coupling agent on the flexural properties of oil palm empty fruit bunch - polypropylene composites

ALCELL lignin has been employed as a coupling agent in oil palm empty fruit bunch (EFB)-polypropylene (PP) composites. The lignin has been chemically modified with hexamethylene diisocyanate (HMDI). Evidence for the reaction between HMDI and lignin has been observed by using Fourier transform infrar ed (FTIR) analysis. The effect of Lignin as a coupling agent on the flexura l properties has been studied. The results show that the HMDI-modified Lign in is able to impart greater compatibility between EFB and PP. This is refl ected in the greater flexural strength shown by the composites with HMDI-mo dified lignin than those with the unmodified lignin. Scanning electron micr oscopy studies show that HMDI-modification of lignin results in a better bl ending and compatibility between lignin and PP matrix. The glass transition temperature of lignin increases as the level of HMDI modification is incre ased. (C) 2001 Society of Chemical Industry.