Scientific African (Jul 2021)
Determination of thermo-mechanical properties of recycled polyurethane from glycolysis polyol
Abstract
Polyurethane foam is one of the most versatile polymers widely used in the automotive industry. However, due to the rising amount of polyurethane foam waste in the environment, there is growing research attention focusing on circular economy solutions to closing the material loop. This study aimed to determine the possible changes in thermo-mechanical properties between rigid polyurethane prepared using polyols derived from depolymerization of commercial polyurethane foam with benchmark rigid polyurethane (Ben PU). Polyurethane foams containing dispersion polyol were reacted with dipropylene glycol (DPG) and diethylene glycol (DEG) with a ratio of DPG: DEG of 1:1 in the presence of a consumable catalyst (Di-n-butyl amine). The recovered polyol was used as a raw material replacing 100% benchmark rigid polyurethane petroleum-based polyester polyol to produce the recycled polyurethane (Rec PU). Thermal analysis was conducted to measure the recycled polyurethane's glass transition temperatures (Tg) using differential scanning calorimetry (DSC). Tensile strength, elastic modulus, toughness, and hardness test of the recycled polyurethane were conducted under three different temperatures; 24°C, 40°C, and 60°C. From the DSC results, the glass transition temperatures for the recycled and the benchmark rigid polyurethane occurred at 43°C and 50.4°C, respectively. Both polymers showed the brittle-ductile transition from 24°C to 40°C. Tensile strength for recycled polyurethane was lower than that of benchmark rigid polyurethane by 29-43% and a corresponding 24-50% decrease in elastic modulus. Recycled polyurethane recorded lower toughness than petroleum-based pure polyurethane by 13-16%. However, the recycled polymer recorded high shored D values than the benchmark rigid polyurethane by 9-29%. This study reveals that recycled polyol could be used as feedstock for polyurethane production with applications tailored to its mechanical properties.
