The present study investigates the manufacturing and characterization of poly(lactic acid) (PLA)-based composites with raw and treated Poaceae, with loadings of 5, 10, and 20% wt. Before composite fabrication, the lignocellulosic fillers were analyzed using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and microscopy to assess their chemical composition, thermal stability, and morphological features. Composites were prepared by melting PLA in a molten state with fillers, followed by injection molding. Comprehensive characterization of the obtained composites included microscopic analysis, melt flow index (MFI) testing, and differential scanning calorimetry (DSC), as well as mechanical tests (tensile and bending tests, impact test). The addition of Poaceae fibers to the PLA matrix significantly affected the mechanical and rheological properties of the composites. Incorporating 5% of cooked or alkalized fibers increased the flexural strength by 57% and 54%, respectively, compared to neat PLA. The modulus of elasticity for the composite with 20% alkalized fibers increased by as much as 35%. The fibers acted as nucleating agents, reducing the cold crystallization temperature (T_cc) by up to 15.6 °C, while alkaline residues contributed to an increased melt flow index (MFI). The conducted research provides a valuable basis and insights into the design of sustainable bio-based composites.

In this study, the processing of stereocomplex poly(lactic acid) (sc‐PLA) via continuous compounding followed by thermoplastic foam injection molding (FIM) is investigated. Various nucleating agents are compounded with a mixture of poly(L‐lactide) (PLLA) and poly(D‐lactide) (PDLA). The crystalline material structures are greatly influenced by the cooling conditions of the extruded strand. In particular, a controlled two‐stage cooling strategy, consisting of initial air cooling followed by water‐bath cooling, effectively suppresses cold crystallization and promotes a predominantly stereocomplex crystallization behavior of the granulates. PLLA and PDLA are compounded with the aluminum complex NA‐21 and talc as nucleating agents and processed into foamed specimens using FIM with nitrogen as a physical blowing agent. X‐ray diffraction confirms a primarily stereocomplex crystalline structure in the foamed specimens, and scanning electron microscopy reveals a closed‐cell foam morphology within the PLA matrix. The present study thus demonstrates the feasibility of stereocomplex crystallite formation in thermoplastic foam injection molding, establishing a processing route for sc‐dominated PLA foam parts that combines the density reduction of foaming with the elevated melting range of the stereocomplex crystalline structure.

In this study, the processing of stereocomplex poly(lactic acid) (sc-PLA) via continuous compounding followed by thermoplastic foam injection moulding (FIM) was investigated. Various nucleating agents were compounded with a mixture of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA). The crystalline material structures were greatly influenced by various cooling conditions of the extruded strand. The resulting thermal morphology of the compounds had a considerable effect on the subsequent injection moulding. In particular, a controlled two-stage cooling-strategy, consisting of initial air cooling followed by water-bath cooling, effectively suppressed cold crystallisation and promoted a fully stereocomplex crystallisation behaviour of the granulates.PLLA and PDLA were compounded with the aluminium complex NA-21 and talc as nucleating agents and processed into foamed specimens using FIM with nitrogen as a physical blowing agent. X-ray diffraction results confirmed a predominantly stereocomplex crystalline structure in the foamed specimens and scanning electron microscopy revealed a closed-cell foam morphology within the PLA matrix. Foamed sc-PLA materials are expected to open new opportunities for the development of sustainable technical applications due to low density and high heat resistance.