Coconut oil driving plastic recycling

PLASTIC components from end-of-life vehicles could be recovered using coconut oil and then recycled into industrial foams, according to researchers in Eastern Europe.

Global automotive plastics consumption is expected to grow from 7.1m t in 2012 to 11.3m t by 2018. Of these plastics, 17% consists of polyurethanes, and 7% polycarbonates. Various methods of chemical recycling exist, but there has been little research into turning recovered polyols into novel materials, such as rigid foams. Foams are widely used for applications such as insulators in building construction and in packaging.

Following previous work showing that coconut oil could degrade polycarbonate, a collaborative team from Poland’s Cracow University of Technology and the Czech Republic’s Institute of Macromolecular Chemistry have sought to increase the potential applications of recovered polyols. The result, reported in ACS Sustainable Chemistry & Engineering, was the preparation of low-density rigid polyurethane and polycarbonate foams containing 50 wt % recycled polyols.

To recover polyols, the researchers used a waste fraction from the soap industry composed uniquely of medium-chain triglycerides of coconut oil. This was transesterified using glycerol, and then used as the reagent for conversions of polyurethanes and polycarbonate wastes. For this conversion, semirigid polyurethane foam and polycarbonate waste from end-of-life vehicles was pressed and cut into small pieces. This was then heated with the transesterified coconut oil in a multimode microwave reactor up to 210-215°C, then cooled and filtered.

Rigid polyurethane foams were then produced using a commercial virgin polyol, which was partially replaced by either of the recycled products up to 50 wt %. Polyols were mixed with a PMDTA catalyst, silicone surfactant and polymeric diphenylmethane diisocyanate, before foams were prepared using n-pentane as a physical blowing agent.

The paper reports that obtained foams demonstrated mechanical properties superior to unrecycled foams, including high compressive strength and a low density. Recycled foams were also demonstrated to be stable at temperatures up to 220°C, with authors suggesting they could be incorporated into insulating materials for the construction industry.

ACS Sustainable Chemistry & Engineering: http://doi.org/b8cw