Packaging: how to improve the thermo-mechanical properties of PLA (poly lactic acid)?
The team Green chemistry and physico-chemistry of ITERG is working on a new research project in collaboration with Henri Cramail of LCPO (Laboratory of Organic Polymer Chemistry) and Patrice Dole of CTCPA.
Entitled Pla2Pack, it is led by Jamie Rubinsten.
Because of its biocompatible nature, PLA has been used for many years in the medical field (suture threads, orthopedic pins or galenics). Due to technological developments and process optimizations, PLA is now available for mass markets such as packaging, single-use objects, fibers, etc.
For the packaging sector, the thermo-mechanical properties of PLA still need to be improved and more particularly
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modulate its gas permeability properties (O2,CO2,H2O) for a better preservation of foodstuffs requiring either aslightly higherO2 barrierthan a standard PLA (delicatessen applications not requiring the contribution of modified atmosphere), or on the contrary a control of respiration requiring levels ofCO2 permeabilityslightly higher than those provided by the standard PLA (cheeses, salads4th range)
- improve its resistance to low temperature impacts,
- to increase its resistance to temperature above Tg (60°C) (e.g. use of the packaging for microwaveable ready meals).
During the thesis, many additives were synthesized.
Pilot scale implementation tests were carried out
at CTCPA. Thus, fatty acid amides have been tested as nucleating agents to increase the crystallization kinetics.
In parallel, structures of estolide type from castor oil but also from rapeseed oil with high erucic content have been implemented to improve the performance of PLA.
These oligomers, post-functionalized or not with epoxy or carbonate groups, have been implemented in PLA by extrusion/molding. The cups produced in this way are currently being evaluated from the point of view of mechanical and thermal properties and gas barrier properties. According to the first elongation analyses, the mechanical gains seem to be confirmed for the non-functionalized estolides. Epoxidized and carbonated estolides seem to decrease the mechanical reinforcement effect.