Iligan City, Philippines – Scientists at the Iligan Institute of Technology’s Centre for Sustainable Polymers have developed a way to make a hydroxyl-rich biopolyol from coconut oil. They believe it should have applications in insulation.
Vegetable oils require chemical modification to insert the necessary hydroxyl groups, typically by double bond epoxidation followed by ring opening reactions. While saturated oils can be modified by transesterification and amidation, the resulting polyols still have low hydroxyl numbers, meaning fossil-based polyol replacement is still necessary if effective rigid PU foams are to be made.
Coconut oil is widely used as a renewable source of raw materials for polyols as it is cheap and abundant, but it is unsaturated. The scientists overcame this by taking triglycerides from coconut oil, and subjecting them to a glycerolysis reaction followed by a catalytic amidation. The result was an amine-based polyol, p-CDEA, with a higher hydroxyl value of 361mg KOH/g than earlier polyols from coconut oil, which ranged from 270–333.
The polyol was then used to make a poly(urethane-urea) hybrid foam with MDI. With a compressive strength of 226kPa and a thermal conductivity of 23.2m–1K–1, according to ASTM standards it can be classified as Type 1 for rigid structural sandwich panel cores, and Type 2 for rigid thermal insulation foam applications.
The team believe this is the first time a coconut oil-based polyol has been created that could be used in insulation applications in place of PU derived from petrochemical sources. A patent application has been filed.
The work has been published in the journal RSC Advances.