Study On The Water Vapor Barrier Of Polylactide Or Poly (Lactic Acid)

Polylactide or poly(lactic acid) (PLA) as a completely biodegradable and bio-based polymer, with special performance:recycle, biocompatibility, biodegradability, has mechanical properties and processing correspond to petro-based resins. Under such circumstance of the shortage of oil resource, environmental pollution and low-carbon lifestyle, PLA attracts wide attentions, and is recognized as the most promising eco-friendly material. But PLA also has performance defects:brittleness, poor heat resistance, insufficient barrier properties, which limit the applied range. It is important to improve the barrier property for expanding the application in packaging industry. Three methods:annealing, blending with ethylene vinyl alcohol copolymer (EVOH), compositing with organic montmorillonite (OMMT) are researched in this study. The results as follow:with increasing crystallinity(Xc), water vapor permeability coefficient(Pv) does not change first (Xc<40%) and then decreases sharply(Xc>40%). Pv decreases by 45% compared to untreated PLA, when Xc is 59%. With increasing EVOH content, Pv of EVOH/PLA decreases gradually. Pv decreases by 61% compared to pure PLA, when the amount of EVOH reaches 50%. With increasing OMMT content, Pv of OMMT/PLA decreases gradually. Pv decreases by 58% compared to pure PLA, when the amount of OMMT reaches 9%.