Kinetic of Hydroxyl Growth on Natural Rubber Depolymerization with H₂O₂/Fenton Using Infrared Spectroscopy

The kinetic of NR depolymerization to HTNR using H2O2 under the presence of Fenton catalyst in acidic environment and ultraviolet radiation has been studied using Infrared Spectroscopy to inspect the changes of molecular weight and functionality of HTNR product. The kinetic model is studied follow reaction mechanism: 1) hydroxyl radical and NR produce radical NR and hydroxylated NR, 2) radical NR and hydroxyl radical produce hydroxylated NR, 3) hydroxylated NR is reacted with hydroxyl radical produce lower radical NR, hydroxylated terminated NR, radical NR, and hydroxylated NR. The NR polymer conversion and total hydroxyl was observed at absorption band of CH2-CH2 and OH group at 850 cm-1 and 3,400 cm-1. Absorption of CH3 at 1850 cm-1 was used as reference group. The average molecular weight is calculated using Stockmayer equation. The hydroxylated NR production follow 2th order, the hydroxylated terminated NR production was conformed to be 1st order. The average molecular weight and functionality of HTNR is well estimated. The temperature effect on depolymerization followed Arrhenius reaction with activation energy Ea1R and Ea34R are 750 K and 1200 K. The effect of H2O2/Fenton ratio on the depolymerization followed power equation with power coefficient are 1.97 and 1.82 for k1and k34.