Chemical modification of rice husk for using in semi rigid PU foams

In this study, Rice Husk(RH) have been modified with PMDI and NaOH solution(5% wt). The effect of the NaOH solution(5% wt) and PMDI modification on % of RH hydroxyl(OH) groups and creative the reactive NCO groups on RH were investigated. The effect of washing with NaOH solution(5% wt) was the reduction of lignin on RH(RL-RH). The free reactive NCO groups were created on RL-RH by the reaction between PMDI and RL-RH. Both of the processes of lignin reduction and creating free NCO groups on RH, were detected in infra-red spectrum. The NCO modified RL-RH is a candidate for using in polyurethane semi-rigid foams