Highly efficient reactive compatibilization of biodegradable PBAT/EVOH blend by pMDI

Abstract Polymeric methylene diphenyl isocyanate (pMDI) was used as a reactive compatibilizer to improve the mechanical properties of the PBAT/EVOH blend. Initially, pMDI was blended with pure polymers. Adding pMDI led to a 10‐fold rise in the viscosity of PBAT/pMDI compared to pure PBAT, with an enhancement in tensile properties, attributed to pMDI's chain‐extending effect in the PBAT phase. Conversely, a reduction in the elongation at the break of EVOH/pMDI indicated a cross‐linking role for pMDI in the EVOH phase. Notably, the blend with 1 wt% of pMDI showed a high tensile strength of 38 MPa by route II, much above 13.5 MPa for the one prepared by route I, and 14 MPa for the blank PBAT/EVOH blend without pMDI. Fourier transform infrared (FTIR) spectra, FE‐SEM images, and dynamic mechanical thermal analysis (DMTA) results confirmed the occurrence of effective reactions in route II. Modification of the blend with pMDI decreased the crystallinity of EVOH, the size of EVOH droplets, and the oxygen transmission rate (OTR) of the blends. However, an increase in the pMDI content above 0.5 wt% decreased OTR. Therefore, the modified blends of PBAT/EVOH with pMDI can be used as an efficient compatibilizer or adhesive layer in PBAT/EVOH blends or multilayer films for agricultural or food packaging applications.