Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

Biopack PLA-based materials

Material Selection and Developments:

Several different polylactides (PLA) have been produced in the course of the project:
- Linear poly (L-lactide);
- Slightly branched polymer with long-chain branching obtained by applying melt-modification during a secondary processing step;
- Copolymer of L-lactide and epsilon-caprolactone;
- Four-arm branched homopolymer based on L-lactide.

The materials have been thoroughly characterised (by GPC, NMR, DSC, TGA) and tested with regards to processing, mechanical and barrier properties. One problem with the manufactured polymers was the high content of residual monomers, which was found to result in a higher water uptake and accordingly in a poor stability of the processed samples. This problem was solved later on in the project by optimisation of the manufacturing process. The lower content of the residual lactide caused a more brittle material, which had to be solved by introducing a softening agent, which was based on a lactic acid copolyester resin. Materials with good mechanical properties could be produced when applying the softening agent. Transparent materials could be produced from the PLA resin. The material produced and tested showed acceptable properties except for the barrier properties, which was found to be too poor for cheese packaging materials. Especially the water vapour transmission was too high.

A solution to the poor barrier properties was sought by means of the following approaches:
- Plasma treatment of the PLA film;
- Coating/compounding with chitosan;
- Coating/compounding with nanoclays (preparation of nanocomposites).

The PLA materials were mainly based on annually renewable, non-gmo resources.

Migration levels of the PLA materials complied with current EU legislation and the PLA materials were in compliance with the EN13432 on compostability.

B. Processing and Processability:
The polylactides are generally considered to be processable by using standard processing equipment and film extrusion, injection moulding and thermoforming was possible to perform on all the materials produced in the project. However, the inclusion of cyclodextrin proved to be difficult. The results indicate that there is a potential for polylactide based materials for use as cheese packaging materials, but the barrier properties need to be further improved or storage time reduced.

The PLA materials have good sealant qualities and may be printed on using standard equipment.

C. Application sectors:
The polylactide materials proved suitable for short-term storage of chilled food and storage of foods with low moisture at room temperature. The use temperature is -30 degrees Celsius to 70 degrees Celsius depending on moisture content.

Contact

Anders SÖDERGÅRD, (Head of Research)
Tél.: +31-59-4505769
Fax: +31-59-4506253
E-mail