Biodegradable packaging from plant fibre composites Flax and hemp have been cultivated for centuries for their use in fabrics, paper and felt, and as a source of animal feed. An EU research project investigated how these plants can become a source of sustainable packaging. Industrial Technologies © Thinkstock The packaging industry is extremely interested in materials derived from renewable resources such as natural fibres. However, the use of biodegradable materials for food packaging has been limited because of the low barrier properties and weak mechanical properties shown by natural polymers. One of the potential approaches to solve this issue and provide enhanced properties was developed on the FLHEA (Flax and hemp advanced fiber based composites) project, which explored the use of these two plants as sustainable source materials for improved packaging. Flax and hemp fibres were selected because of their high cellulose and low lignin contents, offering a faster processing route for the isolation of cellulose micro/nanofibres. As source of cellulose, extraction of fundamental crystalline cellulose regions by acid hydrolysis, resulted in the isolation of cellulose nanocrystalline fractions, also known as nanowhiskers. During the project, researchers developed methods for the easy handling and manipulation of cellulose fibres. From these fibres, nanocrystalline cellulose fractions were isolated. The surfaces of the nanoparticles were chemically modified in order to increase their compatibility with the hydrophobic polymer matrices and to prevent their agglomeration during compounding, achieving a good dispersion and interaction with polymeric matrices. Once compounding process parameters were optimised to ensure the desired distribution of the reinforcing phase in the polymeric matrix, co-extruded sheets were performed at pilot scale. Industrial up-scaling was also carried out, obtaining thermoformed trays for food packaging applications. Scientists found that flax was the best source of fibre due to its higher cellulose content. Researchers also managed to improve the extracted cellulose yield of flax by more than 20 % compared to hemp. FLHEA outcomes will contribute to the development and use of biodegradable materials for packaging purposes. Furthermore, developing these materials from sustainable plants may improve the economy and reduce the environmental costs of packaging. Keywords Flax, hemp, biodegradable materials, food packaging, FLHEA, cellulose
