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Enhancement of molecular weight reduction of natural rubber in triphasic CO2/toluene/H2O systems with hydrogen peroxide for preparation of biobased polyurethanes
Author(s)
Date Issued
January 28, 2019
Type
Article
Abstract
Molecular weight reduction of natural rubber (NR) with hydrogen peroxide (H2O2) oxidizing agent is limited in biphasic water-toluene systems that is attributed to mass transfer. In this work, CO2 was applied to the (aqueous H2O2)-(toluene-NR) systems with the objective of improving reaction efficiency. Experiments were performed on the reaction system with CO2 at 12 MPa and at reaction temperatures and times of 60°C-80°C and 1 h-10 h to evaluate the reaction kinetics. CO2 could enhance the NR molecular weight reduction by lowering the activation energy (from 121 kJ·mol-1 to 38 kJ·mol-1). The role of CO2 in the reaction system seems to be the formation of oxidative peroxycarbonic acid intermediate and promotion of mass transport due to the reduction in the toluene-NR viscosity and interfacial tension. The epoxidized liquid NRs (Mn=4.9×103 g·mol-1) obtained from NR molecular weight reduction was further processed to prepare hydroxyl telechelic NR (Mn=1.0×103 g·mol-1) and biobased polyurethane.
Citation
Green Processing and Synthesis, 8(1), 288-296, 2019