Depolymerization of polyamide 6 in hydrophilic ionic liquids

摘要

Polyamide 6 underwent an efficient depolymerization in hydrophilic ionic liquids under microwave irradiation at 300℃.The depolymerization completed within 60 min.Caprolactam was readily separated by simple extraction procedure and the ionic liquids were recovered and reused for several times.Addition of catalytic amounts of DMAP(N,N-dimethylaminopyridine)promoted the depolymerization effectively.The present improved procedure provides a method to avoid direct distillation procedure,which consumes energy for the separation of caprolactam from ionic liquids.Although some contamination of ionic liquids was observed,the present procedure provides a new possibility for the use of ionic liquids for plastic chemical recycling from the viewpoint of development of an energy-saving methodology.Use of solubility switchable ionic liquids is also examined to explore a possibility for better separation although depolymerization did not work well.