Poly(lactic acid)/montmorillonite blown films: Crystallization, mechanics, and permeation

ABSTRACT The study focuses on the development and characterization of poly(lactic acid) (PLA)/montmorillonite (clay) nanocomposite films. Samples of 0%, 1%, 3%, and 6% (by weight) clay were shear‐mixed, melt‐blended, and blown‐film processed. Afterward, the effects of clay on the kinetics of cold‐crystallization, mechanical properties, and the oxygen barriers are investigated using differential scanning calorimetry, dynamic mechanical analyzer, and permeation tester, respectively. Through the traditional Avrami analysis, clay is found to accelerate the crystallization process with a higher crystallization rate constant. The Avrami exponent obtained for composites is higher than the neat PLA although all samples show a decreased Avrami exponent with increase of the crystallization temperature. At the same time, the clay exhibits reinforcement effects on the glassy modulus of the composites and influences the cold‐crystallization event, similar to the calorimetric results. In addition, the oxygen permeation slightly decreases on adding the clay. With 3% clay concentration, the permeation coefficient is reduced by 24%. The implication of the results is discussed in the article. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45260.