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

Area of Science:

• Polymer Chemistry
• Chemical Kinetics
• Materials Science

Background:

• Natural rubber (NR) depolymerization is crucial for producing functionalized polymers.
• Understanding the kinetics of NR modification is essential for process optimization.

Purpose of the Study:

• To investigate the kinetics of natural rubber (NR) depolymerization to hydroxyl-terminated natural rubber (HTNR).
• To elucidate the reaction mechanisms and the influence of process parameters like temperature and reactant ratios.

Main Methods:

• Utilized infrared spectroscopy to monitor changes in molar mass and functional groups.
• Analyzed kinetic models based on elementary reaction mechanisms.
• Employed absorption bands at 850 cm⁻¹ (CH₂-CH₂) and 3400 cm⁻¹ (OH) for conversion and hydroxyl content determination.
• Used the CH₃ peak at 1850 cm⁻¹ for calibration.

Main Results:

• Depolymerization kinetics followed Arrhenius and power law models.
• Activation energies were determined to be 750 K and 1200 K.
• Power coefficients for the H₂O₂/Fenton ratio were 1.97 and 1.82.
• Infrared spectroscopy effectively tracked NR conversion and HTNR formation.

Conclusions:

• The study provides a detailed kinetic analysis of NR to HTNR conversion.
• Temperature and H₂O₂/Fenton ratio significantly influence the depolymerization process.
• The findings offer insights for controlled synthesis of hydroxyl-terminated natural rubber.