Reactive extrusion preparation and characterization of canola meal composites reinforced by a novel polymeric chain extender

Highlights: • Green canola meal (CM) composite was prepared using PSMG consisting of epoxy and anhydride groups as chain extender. • Canola proteins in the CM meal matrix were cross-linked by PSMG. • Fibers in CM matrix were bonded with canola proteins, thus increasing the interfacial adhesion between them. • The reaction between glycerol used as plasticizer and CM matrix took place and increased the cross-linking degree. • Both mechanical property and thermostability of the modified CM composites were increased. To increase the usage value of canola meal (CM), a by-product of canola oil extraction, poly (styrene-co-maleic anhydride-co-glycidyl methacrylate) (PSMG) was prepared and used as a novel chain extender to modify CM. FTIR tests showed that cross-linking took place in the CM matrix and PSMG was covalent bonded with canola proteins; furthermore, the surface of fibers present in the CM composite was covered by proteins, attributed to the reactivity of anhydride groups on PSMG. The modified CM composites showed more apparent amorphous characteristic with the addition of PSMG, according to DSC results. DMA results suggested that cross-linked proteins could be further coupled by glycerol reacting with the anhydride groups remaining in the cross-linked proteins, and thus the storage moduli and the glass transition temperature (T_g) of the modified CM composites increased with the addition of more PSMG. The reactions of proteins with proteins, proteins with fibers, and proteins with glycerol were further confirmed by TGA. SEM images showed that the CM matrix became much denser and the interfacial adhesion between fibers and the CM matrix was increased by the chemical modification, which also contributed to an increase in the tensile strength of the modified CM composites.