Effect of the epichlorohydrin grafting of starch on its pyrolysis behavior and mechanism

Crosslinking is a common method for preparing biomass-based carbon materials. Corn starch grafted with epichlorohydrin was prepared and then stabilized and carbonized to obtain starch-based near-spherical carbon materials. The pyrolysis of corn starch under the influence of epichlorohydrin was analyzed by TG-MS, and the micro-morphology and crystal structure of the near-spherical carbon materials were characterized by SEM and XRD. The surface chemical evolution of the starch before and after pyrolysis was characterized by in-situ FTIR. The modified starch pyrolysis and the cross-linking reactions between epichlorohydrin and starch were investigated. Results indicate that for the modified starch the temperature at which the weight loss rate is a maximum is lowered so that the pyrolysis is relatively mild, and the destruction of the basic skeleton is reduced and the carbon yield greatly increased compared with pristine starch. The cross-linked starch tends to transform to aromatic structures in pyrolysis, the carbonization degree of the hydrolysate is improved, and the yield of the final product is increased compared to the non-crosslinked material. During pyrolysis, epichlorohydrin cross-links with starch to form a network structure, which stabilizes the starch skeleton, thus reducing the production of volatile small molecules.