Fabricating Strong and Stiff Bioplastics from Whole Spirulina Cells |
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Authors: | Hareesh Iyer Paul Grandgeorge Andrew M. Jimenez Ian R. Campbell Mallory Parker Michael Holden Mathangi Venkatesh Marissa Nelsen Bichlien Nguyen Eleftheria Roumeli |
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Affiliation: | 1. Materials Science and Engineering, University of Washington, 302 Roberts Hall, Seattle, WA, 98195 USA;2. Microsoft Corporation, 1 Microsoft Way, Redmond, WA, 98052 USA |
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Abstract: | Since the 1950s, 8.3 billion tonnes (Bt) of virgin plastics have been produced, of which around 5 Bt have accumulated as waste in oceans and other natural environments, posing severe threats to entire ecosystems. The need for sustainable bio-based alternatives to traditional petroleum-derived plastics is evident. Bioplastics produced from unprocessed biological materials have thus far suffered from heterogeneous and non-cohesive morphologies, which lead to weak mechanical properties and lack of processability, hindering their industrial integration. Here, a fast, simple, and scalable process is presented to transform raw microalgae into a self-bonded, recyclable, and backyard-compostable bioplastic with attractive mechanical properties surpassing those of other biobased plastics such as thermoplastic starch. Upon hot-pressing, the abundant and photosynthetic algae spirulina forms cohesive bioplastics with flexural modulus and strength in the range 3–5 GPa and 25.5–57 MPa, respectively, depending on pre-processing conditions and the addition of nanofillers. The machinability of these bioplastics, along with self-extinguishing properties, make them promising candidates for consumer plastics. Mechanical recycling and fast biodegradation in soil are demonstrated as end-of-life options. Finally, the environmental impacts are discussed in terms of global warming potential, highlighting the benefits of using a carbon-negative feedstock such as spirulina to fabricate plastics. |
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Keywords: | biodegradation bioplastics recycling spirulina |
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