Characterization and application of porous polylactic acid films prepared by nonsolvent-induced phase separation method.

Nonsolvent-induced phase separation (NIPS) method was employed to prepare polylactic acid (PLA) films using N-methyl-2-pyrrolidone (NMP) as a nonsolvent. The morphology and structure of PLA films were characterized, and the application of the films in pork preservation was investigated. When 10 wt% NMP was added, film with uniform porous structures was obtained. The crystalline and Fourier-transform infrared spectra analyses indicated that the addition of NMP during the preparation of PLA films caused their crystalline properties to change, but had no effect on their composition. However, the 10 wt% NMP/PLA film had improved thermal stability, water vapor transmission and oxygen permeability. The results on the changes in pH, total volatile basic nitrogen content and total viable counts of pork during refrigerated storage indicated that the 10 wt% NMP/PLA film could more effectively extend the shelf life of pork than polyethylene film. This work demonstrates the potential of the porous PLA film in pork packaging.