Materials BIO4SELF
Materials BIO4SELF Biobased self-functionalised selfreinforced composite materials based on high performance nanofibrillar PLA fibres By: Thomas Köhler, Pavan Manvi, Christian Vierkötter, Klaus Vonberg, Thomas Gries Institut für Textiltechnik, RWTH Aachen University, Aachen, Germany Guy Buyle, Lien Van der Schueren Centexbel Textile Research Center, Gent, Belgium Gunnar Seide Maastricht University, Maastricht Sci Programme, Maastricht, Netherlands The worldwide demand for replacing fossil-based raw materials for the production of polymers leads to a significant growth of bioplastics in terms of technological developments. However, existing drawbacks for certain bioplastics hinder exploring new fields of application. Polylactic acid (PLA) has proven itself as a potential thermoplastic polymer and a candidate in medical and injection moulding application. Though PLA shows good melt processability, the deployment in high performance applications is still a mile stone due to following drawbacks: • Lower mechanical performance: The mechanical properties of PLA allow the uses in films, packaging, containers (bottles and cups) and medical applications but not enough to use PLA in high performance applications like composites, where filament properties are required equivalent to polyethylene terephthalate (PET) and polyamides (PA). • Limited durability: PLA is sensitive to the hydrolytic degradation, which is also a factor of temperature, moisture and pH value of the medium. In high performance applications with long lifetime, PLA has not yet been a primary choice. Enhancement of mechanical properties and hydrolytic stability is still a challenge for PLA. The application of PLA in high performance applications demands improvement in stiffness, impact strength and product durability. Approach The BIO4SELF project aims for enhanced mechanical properties (stiffness, tensile strength, impact strength) and temperature resistance by reinforcing PLA with LCPs (Liquid Crystalline Polymer) via melt compounding process. Furthermore, the durability of PLA based composites will be improved via incorporating well-chosen anti-hydrolysis agents. Further, inherent self-functionalization via photocatalytic polymers (self-cleaning properties), tailored microcapsules (self-healing) and deformation detection fibres (self-sensing) will be added. The potential of these new to be developed biobased composites will be proven in advanced prototypes for automotive and home appliances. Cost-efficient production of fully biobased composites meeting the demand for high technical performances and sustainability will be pursued by investigating the performances of new biobased materials in plastic manufacturing. Figure 1 displays the production process and the advantages of a yarn based self-reinforced composite that will be investigated in this project. To meet the overall goals 36 bioplastics MAGAZINE [04/16] Vol. 11
Materials there will be developments in each step of the process: incorporation of additives via melt compounding, filament melt spinning of additive incorporated low and high melting point PLA grades, commingling of PLA filaments with variable melting points, weaving commingled PLA yarns and consolidation via hot pressing process to produce composites. The Institut für Textiltechnik of RWTH Aachen University (ITA) will contribute to the project in the development of composite intermediates. ITA will develop a process to combine the filament yarns with low and high melting point (for matrix and reinforcement respectively) by a commingling nozzle. The commingling nozzle has one or more additional openings in cross direction to the yarn path, through which compressed air passes into the yarn path. The compressed air creates turbulences that mix the filaments of both components to produce a hybrid yarn. Furthermore, a weaving process for these yarns will be developed. Composite test specimens will be produced using hot pressing of the woven specimen and will be tested for its mechanical properties. The BIO4SELF consortium is strongly industry driven, including five large enterprises and five SMEs. These are completed with three universities and three research centres. This way BIO4SELF covers all required expertise and infrastructure from academic, applied research and industry from 10 different EU countries. Acknowledgement BIO4SELF is an H2020 project, meaning that it is cofunded by the European Union (grant of EUR 6.8 million). It will last 40 months and started on March 1 st , 2016. It is coordinated by Centexbel, the Belgian research centre for textiles and plastics. www.ita.rwth-aachen.de www.centexbel.be www.maastrichtuniversity.nl Figure 1: Advantages of yarn based approach for the production of self-reinforced PLA composites Compounding Melt spinning Commingling Weaving Consolidation Advantages of yarn based thermoplastic composites Advantages of self reinforced PLA composites • High stiffness and strength at low weight • Use of various textile fabrics possible • Multiple possibilities of function intregration on fibre level • Lower melt flow paths of matrix polymer compared to film stacking • Excellent impact properties • Lower density than glass or carbon fibre reinforced materials • High recyclability • No use of fossil-based polymers bioplastics MAGAZINE [04/16] Vol. 11 37
