Preparation and characterization of maleic anhydride-based double-monomer grafted polylactic acid compatibilizer

Grafted maleic anhydrides (MAHs) are common compatibilizers, and the Epoxy (EP) group exhibits high activity of epoxy functional groups and strong affinity with both acidic and basic groups. Therefore, high efficiency and broad-spectrum compatibilizers can be obtained by grafting these two monomers onto the polymer molecular chain. In this study, the grafted MAH was used as the graft platform to add the second graft monomer, and the bisphenol A epoxy resin (E51) with two epoxy functional groups or the tri-epoxy functional triglycidyl isocyanurate (TGIC), was added into the polylactic acid molecular chain, in order to prepare the double-monomer grafted PLA compatibilizers. Three kinds of compatibilizers, polylactic acid grafted maleic anhydride (PLA-g-MAH), polylactic acid double grafted maleic anhydride/bisphenol A epoxy resin (PLA-g-MAH-E51), and polylactic acid double grafted maleic anhydride/triglycidyl isocyanurate (PLA-g-MAH-TGIC) were successfully prepared using this single-step method. Finally, FTIR and H-1-NMR were adopted to measure the grafting degrees and structures of the grafted products. The grafting degree of PLA-g-MAH20% was 5.36%, the MAH and EP grafting degrees of PLA-g-MAH 20%-E51 6% were 2.47% and 1.15%, respectively, and the MAH and EP grafting degrees of PLA-g-MAH 20%-TGIC6% were 2.30% and 0.93%, respectively. A portion of that EP was grafted onto the PLA molecular chain by reacting with grafted anhydride, resulting in a decrease in the number of grafted anhydride groups.