The poly (lactic acid) (PLA) is a bio-sourced and biodegradable polymer. It could be an alternative to petroleum-based polymers. This biopolymer and its blends shows poor melt strength properties for usual forming process. In this work, we present some promising routes to enhance its processing ability which presents several challenges. Two main routes were selected: (i) the modification structure and architecture of PLA, (ii) blending it with other ductile thermoplastic biopolymer such as the poly (butylene adipate-co-terephtalate) (PBAT).To achieve this objective, various formulations of PLA and its blends with multifunctionalized epoxy, nucleants and plasticizer were prepared and characterized on the basis of their linear viscoelasticity, extensional properties. Interfacial properties of blends were also investigated systematically. The balance of chain extension and branching has also been investigated using solution viscosimetry, Steric exclusion chromatography (SEC) and rheology. We pushed further by characterizing both the structure and thermo-mechanical properties of PLA formulations. The optimized formulations obtained from the two routes were well processed by (i) batch foaming assisted with supercritical CO2. The influence of the foaming parameters, the extent of chain modification as well as the contribution of crystallization on cell morphology was studied. (ii) Blown extrusion which the stability maps of modified PLA and its blends were indeed established. As well, chain extension/branching and a good compatibilization of biopolymer blends allow a great enhancement of the blown processing windows. Furthermore, induced crystallization during process was also demonstrated and assessed. Finally, improvements of thermo-mechanical properties have been obtained. 1. R. Al-Itry, K. Lamnawar, and A. Maazouz, Rheologica acta 53, 7, 2014, 501-517 DOI: 10.1007/s00397-014-0774-2. 2. R. Al-Itry, K. Lamnawar, and A. Maazouz, European Polymer Journal 58, 2014, 90-102 DOI: 10.1016/j.eurpolymj.2014.06.013 3. Mallet B.; Lamnawar K.; Maazouz A. 2014. Polymer Engineering and Science. 54(4), 840-85, DOI: 10.1002/pen.23610.