Design, modeling, and optimization of PLA-PBAT using response surface method: Rheology and comprehensive characterization for 3D printing applications

This study optimized PLA/PBAT blends using the Response Surface Method-Box Behnken Design, resulting in an optimized PLA-PBAT-Joncryl composition based on modeled responses. A strong agreement between predicted and experimental results was observed. Scanning Electron Microscopy images revealed that Joncryl reduced the size of dispersed PBAT particles by 42% and their distribution by 65% compared to the PLA-PBAT sample, leading to a 2314% increase in elongation at break compared to neat PLA. In contrast, samples containing Lotader exhibited larger particle sizes, despite improvements in elongation at break and toughness. The largest reduction in melting temperature (T m ) was observed for PLA-PBAT-Joncryl, confirming improved miscibility. Although crystallinity decreased in the compatibilized blends due to reduced polymer chain mobility, the nucleating effect of PBAT improved crystal quality, as evidenced by higher crystallization temperature (T c ) and enthalpy (ΔH c ). FTIR analysis confirmed complete epoxy group consumption, indicating the effective performance of compatibilizers. The complex viscosity of PLA-PBAT-Joncryl was significantly higher compared to the PLA/PBAT blends and the neat PLA, suggesting enhanced phase interaction. Additionally, higher storage modulus at low frequencies, a steeper terminal slope in Han plots, and a lower intersection between storage and loss moduli indicated superior miscibility in PLA-PBAT-Joncryl. The analysis of 3D-printed samples revealed that the mechanical properties of PLA–PBAT–Joncryl and PLA–PBAT exhibited elongation at break values that were 450% and 1000% higher, respectively, than neat PLA. • Processing parameters and compositions of PLA–PBAT blends optimized using RSM. • Joncryl addition enhanced toughness, elongation, and viscosity of PLA–PBAT blends. • Optimized blend showed finer morphology and superior 3D print performance.