Optimizing crystallinity of engineered poly(lactic acid)/poly(butylene succinate) blends: the role of single and multiple nucleating agents

This work deals with the design and experimental development of formulations based on bioplastic materials optimized for the production processes of high-performance packaging products, suitable for food contact and characterized by high thermo-mechanical stability. For this purpose, mixtures of poly (L-lactic acid) (PLLA)/poly (butylene succinate) (PBS) (PLA/PBS) containing micro-lamellar talc as reinforcing agent and inorganic nucleating agent have been obtained on a pre-industrial scale. Through the addition in formulation of two organic nucleating agents, ethylene (bis)stereamide (EBS) and poly (D-lactic acid) (PDLA), evaluated separately and in combination with each other, four different PLA/PBS formulations were produced by means of a co-rotating twin screw extruder. The effects on the crystallinity of the materials obtained first in the form of pre-dried pellets, then in the form of films by casting extrusion and, finally, as thermoformed items were compared, according to the variation of the chosen nucleation system. The effect on the crystallinity of the materials was assessed by differential scanning calorimetry (DSC) and by Fourier transform infrared analysis in attenuated total reflection mode (ATR-FTIR). This approach aims to provide data for the further investigation on the processability and the thermo-mechanical properties of end-goods achievable by converting processes (melt processing) of the bioplastic compounds.