Effect of Mixing Strategy on the Structure-Properties of the PLA/PBAT Blends Incorporated with CNC

Abstract

Polylactide (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) blend nanocomposites including 3 wt% of cel-lulose nanocrystals (CNCs) were prepared by melt compounding method in a twin-screw extruder and an inter-nal mixer. Blend nanocomposites were formulated by diluting three different masterbatches prepared by solution casting method that contained 7 wt% of CNC. These masterbatches were: (m1) PLA/PBAT/CNC masterbatch; (m2) PLA/CNC masterbatch; and (m3) PBAT/CNC masterbatch. These were to explore how different prepara-tion methods affect the dispersion and localization of CNC and hence the properties of PLA/PBAT/CNC blend nanocomposites. Scanning electron microscopy (SEM) was used to study the structural changes of the blends. Rheological properties of PLA/PBAT blends and PLA/PBAT/CNC blend nanocomposites were also investigated. In the samples prepared by internal mixer, the rheological behavior of blend nanocomposite prepared through premixing of CNC particles with PLA showed a transition from liquid-like to a gel-like behavior. According to the rheological results and differential scanning calorimetry (DSC) analysis, it was found that the CNC overall enhanced the viscoelastic properties of blends and improved the PLA crystallization, respectively. Dynamic mechanical analysis (DMA) illustrated that the incorporation of CNC also enhanced the elastic modulus of PLA/PBAT blends specifically above the glass transition temperature of PLA. The expected improvements in mechanical properties did not occur due to the possible existence of residual solvent in the blends.