Poly(lactic acid) mass transfer properties

Poly(lactic acid) (PLA), a biodegradable and compostable polymer, is gaining market acceptance and has been extensively investigated. The versatility of PLA has led to its broad and different applications in medical, agriculture, and food packaging fields. Similar to other polymers, PLA is permeable to gases, vapors and organic compounds. Thus, the mass transfer properties of PLA can influence its suitability for end-use applications. Here, we present a comprehensive, systematic, and critical review of more than 300 papers published since 1990 reporting the mass transfer properties of PLA, which include permeability, diffusion and solubility to gases, water vapor and organic vapors, along with migration of chemical compounds from PLA. Overall, PLA provides moderate barrier to gases, water vapor, and organic compounds. Barrier enhancement can be achieved through modifications such as blending with other polymers and formation of composite structures. Most of the mass transfer parameters reported in the literature are based on two-phase mobile amorphous and crystalline fractions, omitting the role of the restricted amorphous fraction, which can lead to unclear comprehension of PLA barrier properties as well as what affects those properties. Additional research is needed to address this shortcoming. This review provides an in-depth analysis of PLA mass transfer and a foundation for future research and commercial development.