Preparation of bio-based polyurethane foams from bio-based polyols

Abstract

Bio-based polyester polyols from bio-based acid were synthesized by condensation reaction using succinic acid (SA) and seven different glycols. The effects of chain length of glycol and glycol types (neat or mixed glycols) used to prepare polyols toward physical and mechanical properties of the prepared polyurethane (PU) foams were investigated relatively to PU foam prepared from a commercial polyester polyol. It was found that PU foam prepared from SA and mixture of diethylene glycol (DEG) and glycerol provided good cell size and smallest cell dimension resulting highest compressive strength relative to other types of polyols used in PU foams preparation. The effect of isocyanate (NCO) index on morphology and mechanical properties of foams were also studied. PU foams were prepared from mixed DEG-glycerol polyol and polymeric methylene diphenyl diisocyanate (PMDI) at different NCO indexes relative to PU foams prepared from commercial polyol. The results showed that cell size of PU foams prepared from bio-based polyol were virtually insensitive to NCO indexes, but density and compressive strength increased as the NCO indexes increased. This results was also found in PU foams prepared from commercial polyol. PU foam prepared from bio-based polyol at NCO index of 200 provided highest compressive strength. PU foam/clay nanocomposites were prepared by incorporating two types of clays into PU foam prepared from mixed DEG-glycerol polyol and PMDI at NCO index of 200. The clay contents, both modified (C30B) and unmodified (MMT), were varied at the levels of 0.5, 1, 1.5, 2, 3, 5, and 7 php. It was found that PU foam incorporated with nanoclay C30B at 1 php imparted highest compressive strength.