Structure, morphology and mechanical behaviour of novel bio-based polyurethane composites with microcrystalline cellulose

The aim of this work was to obtain bio-based polyurethane composites using biocomponents such as, bio-glycol, modified natural oil-based polyol, and microcrystalline cellulose (MCC). The prepolymer method was used to prepare the bio-based polyurethane matrix. Prepolymer synthesised from 4,4'-diphenylmethane diisocyanate and a polyol mixture containing 75 wt% commercial polyether and 25 wt% hydroxylated soybean oils (H3) was later subjected to chain extension polymerization with bio-1,3-propanediol acting as a chain extender. Different composites were produced by dispersing 5, 10, 15 and 20 wt% of microcrystalline cellulose powder in the polyurethane matrix. The polymerization reaction was catalyzed with 1,4-diazabicyclo[2.2.2]octane. The influence of MCC content on the structure and the mechanical and thermo-mechanical properties of the obtained bio-based polyurethane composites was investigated. The FTIR analysis demonstrated that the addition of MCC did not significantly change the chemical structure of the obtained composites. The SEM images showed good interfacial adhesion between the bio-filler and the partially bio-based matrix of the composites. The results of thermo-mechanical analysis demonstrated that the application of MCC filler affected the storage and loss moduli. The tensile strength and elongation at break decreased with increasing MCC content. Moreover, the addition of MCC improved the hardness of the obtained environmentally friendly materials.