Reaction of asphalt and maleic anhydride: Kinetics and mechanism

Reaction of asphalt and maleic anhydride (MAH) was investigated by FTIR and chemical titration. FTIR results indicated that chemical reaction between asphalt and MAH did occur, and the cyclic anhydride band in MAH retained during the reaction. Kinetics of the reaction was analyzed by model fitting method when the influence of diffusion was excluded by L9 (34) orthogonal array design. Consequently, models of 3-order reaction and John–Mehl–Avrami (JMA, 1/4) were both justified to be the most possible mechanism functions (MPMFs) of this reaction. The two MPMFs could be understood from diverse viewpoints. Apparently, since the molecular dimension of reaction product enlarged during the reaction, JMA equation was introduced to simulate the process, and Avrami exponent exhibited the disassociation of asphaltenes with temperature. Essentially, from the viewpoint of chemical reaction, 3-order reaction model demonstrated that the reaction occurred not through the single mechanism of Diels–Alder, alternating copolymerization or charge transfer (CT) but through the compound of them; besides, CT mechanism was the basic one. These results provide a new approach to improve the performances of asphalt by CT mechanism and a kind of novel reactive asphalt useful for advanced researches and technologies.