Although bio-based polylactic acid (PLA) thermoplastics are relatively eco-friendly and easy to recycle, composite materials (such as carbon fiber) are much stronger. Now, German scientists claim to combine the advantages of the two with a new PLA composite material.
Unlike traditional petroleum-based plastics, PLA is made from renewable resources such as corn starch, cassava and sugar cane. Not only can it be fully recovered (in places where equipment is available), but it can also be biodegraded within a few years under appropriate conditions, and it can be composted industrially.
Like other plastics used alone, it does not have the mechanical strength or rigidity exhibited by composite materials. However, since these composite materials are made of at least two mixtures, recycling them is a complicated process-generally not considered worth any effort or expense. With this in mind, researchers at the Fraunhofer Institute for Chemical Technology helped create a composite made of braided PLA fibers, which is located in the PLA matrix.
Fiber and matrix are actually made of two different types of bioplastics, the former has a higher melting point than the latter. This means that during the production process, the solid fibers are embedded in a liquid matrix (composed of molten PLA particles), after which the matrix also becomes solid. The recovery process involves simply melting the fiber and matrix at different temperatures.
Fraunhofer claims that PLA composites are stronger and stiffer than the "pure" form of plastics and reportedly can "compete with commercially available self-reinforced polypropylene composites." Moreover, it is said that the manufacturing process is about half that of petroleum-based composite materials, and the amount of carbon dioxide generated per kilogram of material is about half.
Once the technology is further developed, researchers hope that PLA composite materials can find applications in sports, automotive and medical fields. The material is part of the EU Bio4self project, which also includes the Danish Technical University, the Belgian Textile Research Group CENTEXBEL and the Danish Comfil company.