Scientists in Iran used a mixture of used cooking oil and plastic waste to create polyols. The team at Imam Khomeini International University used these polyols to make rigid polyurethane foam.
Used cooking oils can be epoxidized, and these epoxides are then converted into bio-based polyols by reacting with some chemical reagents such as ethylene glycol, glycerol, and triethanolamine. Bio-based polyols can also be prepared by transesterification of oils.
Crude glycerol is the main by-product of the transesterification process of used cooking oil to produce biodiesel, but it contains high impurities such as water, methanol and acylglycerides. It is therefore not economically feasible to purify it.
Various waste plastics can also be used to produce polyols through the glycolysis reaction. The team used polyols from crude glycerol and epoxidized waste cooking oil in the process of recycling three different plastic wastes -- PET, PU and BPA -- resulting in novel plastics with different viscosities and hydroxyl values. Bio-based polyols.
The waste was first depolymerized in diethylene glycol and then reacted with a heated mixture of PGL and EUO over a magnetic nanoparticle catalyst. These new bio-based polyols were then mixed with commercial polyols at 20%, 40% and 60% ratios and reacted with isocyanates to create polyurethane foams.
The apparent density of the foam increases with bio-based polyol content, and high viscosity inhibits bubble growth. Foams made with 20 percent and 40 percent bio-based polyol blends showed "insignificant changes" in insulation, morphology and mechanical properties under heat compared to relatively rigid foam samples. At 60%, the bubble structure is partially deformed, and the mechanical properties under heat have relatively large changes.
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