POLYIMIDE MODIFIED PHENOLIC FOAM

To overcome the shortcomings of pure phenolic resin, such as high brittleness and easy pulverization,the blending modification of phenolic resin with polyimide was introduced. Polyethylene glycol was also added into the phenolic/polyimide composite to investigate its influence on the composite properties. The composites were characterized by FTIR, TG and HRTEM. The peak of C-O stretching vibration (1008 cm(-1)) becomes weaker in phenolic/polyimide composite than that in neat phenolic resin which means that hydrogen bonds form between PI and PF polymer molecules. From the HRTEM morphologies, the formation of interpenetrating networks in phenolic resin composite could be observed. The modified phenolic resin by polyimide shows obvious improvement in thermal stability, compression strength and thermal insulation properties. The chalking rate and water absorption are also reduced. However, the brittleness of the phenolic/polyimide composite still remains high. The addition of polyethylene glycol into the phenolic/polyimide composite can well resolved this problem. The brittleness of the phenolic/polyimide composite system got better while the other properties such as the compression strength, thermal stability and thermal insulation became worse. From the study we could draw a conclusion that the optimum addition quantities of polyimide and polyethylene glycol are 3% to 5% for the improvement of the overall performance of phenolic foam plastic which makes such material meet the criterion for ship standard.