Synthesis and Characterization of Biobased Polyols Produced from Spent Coffee Grounds' Performance in Polyurethane Foams

摘要

Coffee is one of the most consumed beverages in the world and is the second largest traded commodity after petroleum. According to the recent report of the United States Department of Agriculture, 160.5 million bags (60 kilograms per bag) of coffee beans were produced in 2017, which translates into 6.26 million tons of spent coffee grounds (SCG) residue left over from treatment of coffee powder with hot water or steam in preparation of coffee drinks. The facts that 1) SCG consist 98% of biomaterials (mostly cellulosic materials and extractable sugars) and less than 2% ash and 2) that about 50% of the total SCG is a readily available industrial waste generated in instant coffee manufacturing, makes this biomass residue a viable source for sustainable production of renewable products including polyols for polyurethanes. This study reports on synthesis of SCG-based polyol via an acid liquification process. The resulting SCG-based polyol meets acidity standards of commercial polyurethane polyols. The polyol was fully characterized and evaluated in a model rigid water-blown polyurethane pour-in-place foam system, a TDI-based resilient foam formulation model, and an MDI-based viscoelastic foam formulation model system. The impact of SCG-based polyols was assessed on the foaming reaction profile, polyurethane foam cell morphology, physico-mechanical properties, and dimensional stability.