Polyurethane Rigid Foam Derived from Reduced Sweet Whey Permeate

Low-pressure propoxylation of reduced whey permeate (RWP) with different water contents (12.7 and 33.4%) under alkaline conditions afforded polyether polyols (PEP) which have been characterized by their 1H-NMR, HPLC, hydroxyl number, viscosity, unsaturation content, and alpha color. The results were compared with those from lactitol- and sucrose-based polyether polyols (LPEP and SPEP, respectively). Compared with LPEP and SPEP, polyether polyols from reduced whey permeate (RWP-PEP) showed relatively higher hydroxyl number, lower viscosity, and a similar degree of unsaturation. RWP-PEP was generally darker in color. In addition, polyurethane rigid foams (PURFs) from RWP-PEP, LPEP, and commercial sucrose−glycerin-based polyols (Voranol-PEP) were prepared and characterized. All PURFs made from RWP-PEP have low densities (from 28 to 29 kg/m3) and high closed cell contents (>73%). Compressive strength ranged from 13 to 17 kg × 1000/m2 at 10% deformation. These foams have similar thermal stability as the commer...