Transform poly (lactic acid) packaging film from brittleness to toughness using traditional industrial equipments

Abstract

In order to produce the poly lactide (PLA) packaging film with excellent toughness, we adopted a new technological process: isothermal crystallization and then blowing film at the temperature lower than that completely melting of PLA crystals. The elongation at break of PLA film increased to around 67.50% and 104.83% in the transverse direction (TD) and machine direction (MD), respectively. Besides, the tensile strength increased to about 45.4 MPa and 78.0 MPa in TD and MD, respectively. The desirable balance between tension ductility and strength of film attributed to the introduced crystal-cross linked network. During blow molding, the crystallization fields and surrounding linked non-crystalline regions oriented and formed a network under the effect of inflating and pulling forces. The crystal network, bearing the external forces, induced the amorphous regions plastic deformation during stretching, and so improved the tension toughness and strength of PLA film.