Analysis of Factors Affecting the Recycling of Waste Polyisocyanurate Foams

Polyisocyanurate (PIR) foam is a modified polyurethane material that cannot be easily degraded using conventional methods. A process route for degrading PIR waste via alcoholysis was investigated in this study. The effects of conditions such as the type of alcoholysis agent, amount of alcoholysis agent used, duration of alcoholysis, ratio of two-component alcoholysis agent compounding, and amount of catalyst were discussed. The optimum alcoholysis process parameters for waste polyisocyanurate and the use of alcoholysis products for preparing recycled PIR were determined. It was found that the alcoholysis material obtained from the alcoholysis of PIR using diethylene glycol or butylene glycol had low viscosity. The compound ratio of butylene glycol: diethylene glycol a = 43:57 was found to be the best two-component alcoholysis type and ratio under the experimental conditions of alcoholysis time = 2 h, alcoholysis temperature = 180°C, and catalyst = 0.3 w% NaOH; the viscosity of the alcoholysis material was 2351 mPa·s. The resulting recycled-PIR foams showed the best thermal stability and compressive strength and demonstrated the best compressive properties. They had a 17.6% lower thermal conductivity and 12.7% higher compressive strength compared with those of commercially available PIR shells.