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Nowadays, the development of products from renewable raw material has been an important subject of interest for a great number of researchers. Poly(lactic acid) is versatile polymer, synthesized from renewable resources, biodegradable and biocompatible and that has been considered as stronger candidate to replace fossil-based polymers in many application. However, the PLA still has some shortcomings to be solved, such as low thermal resistance, rate crystallization, impact resistance and gas barrier properties. Thus, adding nanofiller can be an interesting method to extend and to improve the PLA properties. The aim of this work is to evaluate the rheological and thermal properties of composites based on PLA/nano-CaCO3/HDPE by using a design of experiments (DOE)-2n Factorial, with three center points. Three factors were studied: HDPE/nano-CaCO3 masterbatch content, temperature and mixer speed. All PLA/Nano-CaCO3/HDPE experiments were characterized by differential scanning calorimetry (DSC), torque rheometry and melt flow index analysis (MFI). It was noticed that torque rheometry was affected by the addition of the HDPE/nano- CaCO3 masterbatch content and it was also observed a synergism among the factors. The nanofiller content, added in the masterbatch, also affected the flow behavior of composites produced. [ABSTRACT FROM AUTHOR]

In recent years, extensive studies have been conducted on the study of the poly(lactic acid) (PLA) properties, because of its being a typical biobased and biodegradable polymer, with good mechanical properties. However, its toughness and gas barrier properties are not satisfactory and can be improved by the addition of nanofillers, such as calcium carbonate (n-CaCO3). The present work PLA composites with nano-sized precipitated calcium carbonate (n-NPCC) were prepared by melt extrusion. Thermal, mechanical and flow properties of the composites were evaluated by using a factorial design. The results showed that the addition of the nanofiller in the PLA matrix didn't improve thethermal and mechanical properties of the matrix significantly. This behavior is probably due to the presence of the stearic acid that is coating on the n-NPCC particles, resulting in a weak polymer-particle interaction. Beyond this, it was also observed a decrease in MFI of the composites when nanofiller was added and at a higher screw speed. [ABSTRACT FROM AUTHOR]