New nanocomposite design from zeolite and poly(lactic acid)

• New composites based on PLA and zeolites for packaging applications have been prepared, studied and compared.
• The barrier properties were slightly improved and no significant differences have been found between the composites and the nanocomposites.
• The mechanical properties of the nanocomposites are significantly improved in comparison to the neat PLA and to the biocomposites.
• The bacteriostatic tests showed that antibacterial properties are significantly improved in comparison to the neat PLA.

We studied the effect of zeolites (NaAlO2, SiO2) and their dispersion in biopolymer poly(lactic acid) (PLA), with a particular interest in the improvement of antibacterial properties, permeability to water vapor, oxygen permeability and mechanical properties. Using two zeolite particles of a different size: micrometric (zeolites) and nanometric (Nanozeolites) sizes, we prepared these composites using the melt mixing process/technique by means of a Brabender mixer. We started by characterizing the morphology of these composite materials using a scanning electronic microscope (SEM) and NanoSIMS microscopies. A good dispersion of nanozeolites is ensured only when a stabilizer (polyethylene glycol (PEG) with M = 1000 g/mol) is used. Then a comparative study on the physical (gas barrier properties) and mechanical properties (high strain mechanical properties) of these two families of composites has been conducted. It was shown that these two families present almost similar barrier and anti-bacterial properties. The strong point of the nanocomposites is their good mechanical properties (high young modulus and high tensile strength). These mechanical and physical properties of the nanocomposites are ensured only when a PEG of M = 1000 g/mol is used as stabilizer.