Mechanism and Kinetics of the Spontaneous Thermal Copolymerization of Styrene/Maleic Anhydride. Experimental and Simulation Studies in the Presence of 4‐oxo‐TEMPO

The mechanism and kinetics of the spontaneous copolymerization of styrene (S) and maleic anhydride (MA) in the presence of 4‐oxo‐TEMPO nitroxide (N) were studied. Experiments were performed at 125 °C varying the S/MA and the N/S ratios and the evolution of conversion was measured by dilatometry up to 20% conversion. Clean induction periods or severe retardation in the initial stage of the reaction were observed. From a proposed kinetic mechanism a mathematical model was built, which was used for fitting the relevant kinetic constants for the self‐initiation steps, and the ratio ${{\bar {k}_{\rm p} } \mathord{\left/ {\vphantom {{\bar {k}_{\rm p} } {\bar {k}_{\rm t}^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} }}} \right. \kern-\nulldelimiterspace} {\bar {k}_{\rm t}^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} }}$ . The model performs well in certain concentration regimes, but it remains a challenge to completely understand this complex system in other concentration regimes.