A Study on the Mechanical Properties, Physical Properties and Biodegradation of Rigid Polyurethane Foam Synthesized from Castor and Palm Oils Based Polyol

This study aimed to synthesize rigid polyurethane foam as an insulating material using castor oil and palm oil to improve biodegradability and replace petroleum-based polyols. Both oils were modified to increase their hydroxyl values before being polymerized with polymeric diphenylmethane diisocyanate (PMDI). The research varied the weight ratios of castor oil and palm oil and examined their effects on the mechanical and physical properties of the synthesized foam, including microstructure, bulk density, compressive strength, thermal conductivity, and biodegradability through hydrolysis. The foam exhibited a predominantly spherical, closed-cell structure. An increased proportion of palm oil-based polyol led to higher bulk density and compressive strength, which can be attributed to its higher hydroxyl value of 437.2 as compared to 414.8 for castor oil polyol, as well as the smaller foam cell size associated with higher palm oil content. However, ANOVA analysis indicated no significant change in thermal conductivity at a 95% confidence level, with values remaining within the range of 0.0512–0.0542 W/m·K.  All measured properties exceeded the standard values for commercial foam. Additionally, biodegradability in the phosphate buffer solution decreased as the palm oil polyol content increased. Further optimization of synthesis conditions or renewable raw materials is necessary to achieve properties comparable to commercial foam.