Depolymerization of Nylon 6 Using Subcritical Water

When nylon 6 is decomposed for 20 minutes at 350 degrees C, and 16.5 MPa of saturated vapor pressure in subcritical water, the decomposition ratio of nylon 6 was 99.1% and the yields of epsilon-caprolactam and epsilon-aminocaproic acid were 69.2% and 13.4%, respectively. In subcritical water, the reversible reaction between epsilon-caprolactam and epsilon-aminocaproic acid occurs and their equilibrium molar ratio was about 10:1 at 300 degrees C and with saturated vapor pressure. Furthermore, epsilon-aminocaproic acid decomposed to a byproduct. The calculated reaction time dependences of the yields of epsilon-caprolactam and epsilon-aminocaproic acid and the amount of the remaining nylon 6 for the whole hydrolysis route in subcritical water, agreed well with the experimental data. (C) 2013, The Society of Polymer Science, Japan