Water‐Blown Rigid Biofoams from Soy‐Based Biopolyurethane and Microcrystalline Cellulose

A novel soy‐based polyurethane biofoam (BioPU) from two polyols (soybean oil‐derived polyols SOPEP and petrochemical polyol Jeffol A‐630 = 1:1 in weight) and poly (diphenylmethane diisocyanate) (pMDI) has been prepared by using a free‐rise method with water as a blowing agent, and microcrystalline cellulose (MCC) as a reinforcement. The photographs of the samples show that the biofoams have similar appearances, and the cell morphology of the resulting biofoams was examined by scanning electron microscope. Density of the composites decreased as a result of increase in MCC content. FTIR study exhibited characteristic peaks for MCC and BioPU. Mechanical properties such as compressive strength, compressive modulus, flexural strength and flexural modulus of the samples were substantially improved with the increase in MCC content. Similarly, improvements in glass transition temperature (Tg) and storage modulus around and after Tg of the neat biofoam were also observed with the composites. Dynamic mechanical analysis results showed an improvement in mechanical properties as well as better thermal stability of the composites over the neat biofoam. Thermogravimetric analysis showed improved thermal stability of the biofoams reinforced with MCC. This research has provided a simple method for preparing the biofoam, while exploring the potential of substituting up to 50 % of the petroleum‐based polyol in biofoam applications.