Introduction to Polylactic Acid (PLA) Composites: State of the Art, Opportunities, New Challenges, and Future Outlook

The first two decades of the 21st century saw immense interest in biodegradable polymer composite systems, sparked by government legislation responding to environmental concerns from organizations and the public. Polylactic acid (PLA) is currently the most prominent bio-polymer, with production estimated to double every few years in the near future, offering an alternative to traditional fossil-based plastics in terms of stiffness and strength. Cellulose, as a reinforcement for PLA, is an abundant natural fiber, and in the form of cellulose nanofibrils (CNFs) or cellulose nanocrystals (CNCs), has been shown to enhance mechanical and barrier properties of PLA. In order for the constituents to interact efficiently, different approaches are chosen to chemically modify cellulose, preventing agglomeration of the fibers and enabling stress transfer to the PLA matrix. The current chapter focusses on environment-friendly production methods and structure-property relationships, to create cellulose-PLA composites for industrial applications where tailored properties and degradability are required, for example, in food packaging.