Influence of NCO/OH ratio on preparation of four agricultural wastes liquefied polyols based polyurethane foams

Four kinds of agricultural wastes (oilseed rape straw (OS), rice straw (RS), wheat straw (WS) and corn stover (CS)) liquefied polyols were used to replace petroleum based polyol and prepare bio-based polyurethane (PU) foam successfully. The effect of NCO/OH ratio on PU foaming process and foams properties, such as density, compressive strength, elastic modulus, morphological structure, storage modulus (E'), glass transition temperature (T-g), water absorption ability and chemical structure, was investigated respectively. It is confirmed that CS based polyol appears the highest activity to react with pMDI, while reactivity of OS based polyol is the lowest. Foams made with NCO/OH ratio among 1.4-1.7 appear excellent morphological, physical, mechanical, water absorption and chemical properties, which are comparable with or even better than those of petroleum polyol based PU foams. (C) 2020 Elsevier Ltd. All rights reserved.