The Preparation and Performance of Phenolic Foams Modified by Active Polypropylene Glycol

A series of active polypropylene glycols (APPGs) were synthesized by the reaction of hexamethylene-1,6-diisocyanate (HDI) and polypropylene glycol (PPG). They were then mixed and reacted with resol resin in catalyst condition to prepare the phenolic foams. The structure of modified phenolic foams was investigated. The influence of M _n of PPG and proportion of APPG on mechanical and fire-retardant performances of foams was discussed. The research results showed that the flexible PPG can be inducted into the crosslink structure of phenolic foam by the together crosslink reaction of –NCO groups in APPG with –CH ₂ –OH groups in resol resin. When the molecular weight of PPG was 2000 and the dosage of APPG was 15% the max strain increased by 87%, mass loss (friability) decreased by 52%, thermal conductivity decrease from 0.033 to 0.028 W/(m·K), meanwhile the LOI can maintain above 30.