The use of Bio-based and biodegradable materials in packaging industry requires many improvements in mechanical, optical and performance of commercially available biopolymers. Specifically in this study, our focus is on the improvement of their properties for use in seal layer application. Many studies on Poly (lactic acid) have shown that its brittleness is the main draw back and attempts have been made to overcome this shortage. In this study, two different aliphatic polyesters, with low stiffness and high elongation at break, have been chosen to be melt blended with PLA. The main difference between the two modifiers is in their melting point with respect to PLA seal initiation temperature. The samples have been melt extruded into films with the thickness of 30μm. A PET film was adhesively laminated to the PLA modified films. The results obtained from differential scanning calorimetry (DSC) suggest a strong relation between surface adhesion of the film in seal area and crystal content of blends. The significant decrease in the crystallinity of phases have provided more mobile chains in the elevated temperature of sealing process leading to significantly improved seal strength of up to twice and seal initiation temperature decrease of up to 30°C. The latter combined with the laminar morphology of blends, which was developed under the elongational flow field of film casting process, provide us with seal layer films of good mechanical and seal properties. Lower modulus and higher elongation at break were obtained even for modifier concentrations as low as 10%. Elongation at break increased from 4% in PLA to around 150% for blends of 10% modifier. The clarity of the blends with 10% and 20% modifier was also in an acceptable range. Both modifiers were effective in decreasing the seal initiation temperature of the PLA but as the content of modifier increased, the seal initiation temperature shifts to the melting point of each modifier.