Biodegradation of Rigid Polyurethane Foam from Castor Oil with Polylactic Acid Addition

This research aimed to synthesize the rigid polyurethane insulation foam from castor oil with an addition of polylactic acid (PLA) to increase its biodegradability. Castor oil was modified to contain a higher hydroxyl value, before it was later polymerized with polymeric diphenylmethane diisocyanate (PMDI). In this research, the effect of an isocyanate index on the mechanical and physical properties as well as the effect of PLA addition on the biodegradability of the synthesized foam were studied. The foam was found to contain closed spherical cells in the range of an isocyanate index of 100 – 180. When the isocyanate index was increased from 100 to 180, the compressive strength and apparent density of the synthesized foam were increased while the thermal conductivity was decreased. The lowest thermal conductivity of 0.019 W/m.K was satisfactorily obtained in this work. Using the isocyanate index of 180 with an PLA addition of 0 – 20 php, it was found that the higher PLA content resulted in a decrease in compressive strength and apparent density and an increase in the thermal conductivity. However, the highest foam biodegradability from the hydrolysis in phosphate buffer solution and being buried in the soil for 40 days were observed with the 20 php PLA addition at 16.61 % and 8.47 %, respectively.