Using Modified Castor Oil as Bio‐Polyol in Preparation of Water‐Blown Rigid Polyurethane Foam with Microcrystalline Cellulose Reinforcement

Abstract In this study, castor oil (CO) used as bio‐polyol is modified by the transamidation process with diethanol amine to increase the hydroxyl group content before water‐blown rigid polyurethane foam preparation. Microcrystalline cellulose (MCC) as a natural filler is added to the polymer matrix to evaluate reinforced efficiency. Amidated castor oil is characterized by H‐nuclear magnetic resonance (1H‐NMR) and Fourier transform infrared spectrometry (FTIR). The morphology of closed cells is studied by Scanning electron microscopy (SEM). Density and compression strength of polyurethane foam composite are performed following ASTM 1622 and ASTM D1621, respectively. The results showed that foam loading 3% filler has high closed‐cell density, narrow size distribution in the range of 140–180 µm, the cell size is reduced by ≈33%, and compression strength is enhanced by 150%, in comparison with pure foam. Adding microcrystalline cellulose as a bio‐filler improved the morphology and mechanical properties of foams and can be considered an interesting bio‐material in various potential fields.