Poly(lactic acid) (PLA), a biodegradable polymer, has high tensile strength, high gloss and clarity, good heat sealability and low coefficient of friction. However, it also has some drawbacks, such as low heat distortion temperature and high gas/liquid permeability (weak barrier properties). Furthermore, PLA is not suitable for some important polymer processing operations, such as film blowing and blow molding, due to its low melt strength. The present work considers the feasibility of improving the processability and mechanical properties of poly(lactic acid) (PLA) by a combination of some or all of the following approaches: (i) blending with another biodegradable polymer with lower glass transition temperature such as poly[(butylene succinate)-co-adipate)] (PBSA), (ii) the addition of an epoxy chain extender, and (iii) the formation of nanocomposites incorporating clay or nanocrystalline cellulose (NCC). Based on earlier work, the following PLA/PBSA blend ratios (90:10, 80:20, 70:30) were selected. The rheological and mechanical properties of these blends were evaluated at 2% wt. for both chain extender and nanoparticle contents. All the samples were prepared using a twin-screw extruder at two different screw speeds (50 and 150 rpm) , to evaluate the effects of residence times and processing conditions. The morphology and structure of the blends were examined using field emission scanning electron microscopy. XRD patterns were obtained to evaluate the structure of the nanocomposites. Branching and other chemical parameters were evaluated using NMR and other techniques. Rheological properties (dynamic oscillatory shear measurements and elongational viscosities) of the pure components, blends, and nanocomposites were studied in detail. The rheological and mechanical properties were correlated with the composition and morphology of the blends and the nanocomposites.