Dynamic reactive synthesis of bio-based compatibilizer via diepoxide monomers grafting polylactic acid and reactive compatibilization of incompatible polylactic acid/bamboo powder composites

The synthesis of monomers with two epoxy structures (EIA) was successfully achieved by adopting holo-biobased feedstocks and in situ solvolysis reaction. The molecular structure of EIA was subjected to characterization through the use of infrared spectroscopy (IR), mass spectrometry (MS), and nuclear magnetic resonance hydrogen spectroscopy (¹H NMR). The EIA was employed as the epoxy monomers for the synthesis of the grafted compatibilizer, resulting in the successful preparation of a fully bio-based and high epoxy value grafted compatibilizer (PLA-g-EIA (PLE)). The effects of varying proportions of the monomer (EIA) and Bis(tert-butylperoxy-1-methylethyl)-benzene (BIBP) on the dynamic grafting reaction were investigated systematically using IR, ¹H NMR, melt flow index (MFR), and differential scanning calorimetry (DSC). Furthermore, the compatible effects of PLE on the mechanical performances, rheological properties, and microstructure of bamboo powder (BP) enhanced PLA composites were also investigated. Furthermore, a series of comparisons were conducted between PLE and a homemade PLG under identical conditions. The grafting degree (GD) of PLE reached 1.28 % under identical conditions (monomer mass addition of 3 %, monomer: initiator mass ratio of 20:3), whereas the GD of homemade PLA-g-GMA (PLG) was only 0.82 %. In comparison to PLG with varying contents, the prepared PLE markedly augmented the interfacial adhesion between two phases, thereby promoting an enhancement of impact, tensile, and flexural strength. Furthermore, the presence of PLE (5 wt%) enhanced the impact strength by up to 37 %, tensile strength by up to 3.03 MPa, and flexural strength by up to 6.16 MPa of PLA/BP composites compared to the absence of the compatibilizers. Meanwhile, PLE (5 wt%) was 1.68, 2.16, and 2.02 times more effective than PLG in enhancing the notch impact, tensile, and bending strength of composites, respectively.