Monomerization of nylon 6 in sub- and supercritical water

Nylon 6, which is a polymer synthesized by ring-opening polymerization of epsilon -caprolactam, was decomposed by hydrolysis in sub- and supercritical water. Nylon 6 and degassed water were charged into a batch reactor and heated to a reaction temperature in the range of 573 similar to 673 K for 5 to 60 min in a salt bath. The liquid phase of the product was analyzed by HPLC and GC-MS. As a result of HPLC analysis, epsilon -caprolactam and epsilon -aminocaproic acid were detected in the product liquid phase. The yields of monomer components were plotted as a function of reaction time and temperature. The total yields of these monomers were about 100% for reactions at 573 K in 60 min and at 603 K in 30 min. The yield of epsilon -aminocaproic acid decreased rapidly as reaction time increased. Nylon 6 was decomposed by hydrolysis to epsilon -aminocaproic acid followed by cyclodehydration to epsilon -caprolactam or decomposition further to smaller molecules in sub- and super critical water.