vor 2 Monaten


  • Text
  • Bioplastics
  • Materials
  • Talc
  • Injection
  • Biobased
  • Moulding
  • Plastics
  • Renewable
  • Products
  • Properties

Materials Case Study-3:

Materials Case Study-3: Light-24 Product description Pigmented profiled panels (Light-24), processed by hand lay-up open moulding technique (cold process) for interior and exterior architectural cladding systems. Materials, design and production description Palm-fibres were applied in their long natural form, without chopping after being combined in a mat-form, with a bioresin of two components that hardened at room temperature in 24 hours. This bioresin is a vacuum moulding low-viscosity resin prepared from sunflower esters and caprolactones with various additives. Black light pigment was mixed in a ratio of 2% to the total bioresin mixture. Then by hand lay-up technique, the fibres were impregnated with the resin and pressed in several layers and finally pressed as one thick layer. Conclusions -The manufactured green biocomposites were tested for weathering conditions (according to Free Weathering Test- DIN EN ISO 877) for 24 months as well as mechanically tested. The results were satisfactory and have shown high stability of the material against UV rays and weathering conditions. Mechanical testing showed comparable stiffness values with existing non-structural materials available in local markets that are applied in different architectural applications. This reveals the potential of replacing existing conventional materials with renewable resourced products based on cheap natural fibres and bioresins. Further experimentations and designs should be proceeded by architects, designers and material engineers to reveal more attractive ecological biocomposite products for eco-architecture. - Using agro-fibres and applying them in the form of biocomposites, utilizing biobased matrices based on renewable resources, can offer the opportunity to open a new market for green biocomposite materials with lower prices and acceptable performances, reducing resources consumption and providing more sustainability aspects. Fig. 5. Illustration of the Light-24 product, during manufacturing and after fabrication. Photo credit: Dahy, H. CO 2 as Chemical feedstock – a challenge for sustainable chemistry 3 rd 1 st Day (2 December 2014, 10 am – 7 pm): Political framework and vision: 2 nd Day (3 December 2014, 9 am – 7 pm): Chemicals and energy from CO 2 : Entrance Fee ye s y (2 nue Undergraduate and PhD students can attend the conference with a 50 % discount. Dominik Vogt Venue nova-Institute 30 bioplastics MAGAZINE [03/14] Vol. 9

Materials Bioplastic from shrimp shell (Photo: Harvard‘s Wyss Institute) Researchers at Harvard‘s Wyss Institute (Boston, Massachussetts, USA) have developed a bioplastic from chitosan, a form of chitin, which is a powerful player in the world of natural polymers and the second most abundant organic material on Earth. Chitin is a long-chain polysaccharide that is responsible for the hardy shells of shrimps and other crustaceans, the exoskeleton of many insects, tough fungal cell walls — and flexible butterfly wings. The majority of available chitin in the world comes from discarded shrimp shells, and is either thrown away or used in fertilizers, cosmetics, or dietary supplements, for example. However, engineering successes have been limited to fabricate complex three-dimensional shapes using chitinbased materials — until now. The Wyss Institute team, led by Javier Fernandez and Founding Director Don Ingber, developed a new way to process the material so that it can be used to fabricate large objects with complex shapes using traditional casting or injection molding manufacturing techniques. What‘s more, their chitosan bioplastic is biodegradable in appropriate environments and it releases rich nutrients that efficiently support plant growth. “There is an urgent need in many industries for sustainable materials that can be mass produced,“ Ingber said. Ingber is also the Judah Folkman Professor of Vascular Biology at Boston Children‘s Hospital and Harvard Medical School, and Professor of Bioengineering at the Harvard School of Engineering and Applied Sciences. “Our scalable manufacturing method shows that chitosan, which is readily available and inexpensive, can serve as a viable bioplastic that could potentially be used instead of conventional plastics for numerous industrial applications.“ It turns out the small stuff really mattered, Fernandez said. After subjecting chitosan to a battery of tests, he learned that the molecular geometry of chitosan is very sensitive to the method used to formulate it. The goal, therefore, was to fabricate the chitosan in a way that preserves the integrity of its natural molecular structure, thus maintaining its strong mechanical properties. “Depending on the fabrication method, you either get a chitosan material that is brittle and opaque, and therefore not usable, or tough and transparent, which is what we were after,“ said Fernandez. After fully characterizing in detail how factors like temperature and concentration affect the mechanical properties of chitosan on a molecular level, Fernandez and Ingber honed in on a method that produced a pliable liquid crystal material that was just right for use in large-scale manufacturing methods, such as casting and injection molding. Significantly, they also found a way to combat the problem of shrinkage whereby the chitosan polymer fails to maintain its original shape after the injection molding process. Adding wood flour, a waste product from wood processing, solved this problem. “You can make virtually any shape with impressive precision from this type of chitosan,“ said Fernandez, who molded a series of chess pieces to illustrate the point. The material can also be modified for use in water and also easily dyed by changing the acidity of the chitosan solution. And the dyes can be collected again and reused when the material is recycled. The next challenge is for the team to continue to refine their chitosan fabrication methods so that they can take them out of the laboratory, and move them into a commercial manufacturing facility with an industrial partner. MT bioplastics MAGAZINE [03/14] Vol. 9 31

bioplastics MAGAZINE ePaper