MSGID: 1:317/3 64acdb4e   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    New biodegradable plastics are compostable in your backyard    
      
     Date:   
         July 10, 2023   
     Source:   
         University of Washington   
     Summary:   
         Researchers have developed new bioplastics that degrade on the   
         same timescale as a banana peel in a backyard compost bin.   
      
      
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   We use plastics in almost every aspect of our lives. These materials   
   are cheap to make and incredibly stable. The problem comes when we're   
   done using something plastic -- it can persist in the environment   
   for years. Over time, plastic will break down into smaller fragments,   
   called microplastics, that can pose significant environmental and health   
   concerns.   
      
   The best-case solution would be to use bio-based plastics that biodegrade   
   instead, but many of those bioplastics are not designed to degrade in   
   backyard composting conditions. They must be processed in commercial   
   composting facilities, which are not accessible in all regions of the   
   country.   
      
   A team led by researchers at the University of Washington has developed   
   new bioplastics that degrade on the same timescale as a banana peel in a   
   backyard compost bin. These bioplastics are made entirely from powdered   
   blue-green cyanobacteria cells, otherwise known as spirulina. The team   
   used heat and pressure to form the spirulina powder into various shapes,   
   the same processing technique used to create conventional plastics. The   
   UW team's bioplastics have mechanical properties that are comparable to   
   single-use, petroleum-derived plastics.   
      
   The team published these findings June 20 in Advanced Functional   
   Materials.   
      
   "We were motivated to create bioplastics that are both bio-derived and   
   biodegradable in our backyards, while also being processable, scalable and   
   recyclable," said senior author Eleftheria Roumeli, UW assistant professor   
   of materials science and engineering. "The bioplastics we have developed,   
   using only spirulina, not only have a degradation profile similar to   
   organic waste, but also are on average 10 times stronger and stiffer   
   than previously reported spirulina bioplastics. These properties open   
   up new possibilities for the practical application of spirulina-based   
   plastics in various industries, including disposable food packaging or   
   household plastics, such as bottles or trays."  The researchers opted   
   to use spirulina to make their bioplastics for a few reasons. First of   
   all, it can be cultivated on large scales because people already use   
   it for various foods and cosmetics. Also, spirulina cells sequester   
   carbon dioxide as they grow, making this biomass a carbon-neutral,   
   or potentially carbon-negative, feedstock for plastics.   
      
   "Spirulina also has unique fire-resistant properties," said lead   
   author Hareesh Iyer, a UW materials science and engineering doctoral   
   student. "When exposed to fire, it instantly self-extinguishes,   
   unlike many traditional plastics that either combust or melt. This   
   fire-resistant characteristic makes spirulina- based plastics advantageous   
   for applications where traditional plastics may not be suitable due to   
   their flammability. One example could be plastic racks in data centers   
   because the systems that are used to keep the servers cool can get very   
   hot."  Creating plastic products often involves a process that uses heat   
   and pressure to shape the plastic into a desired shape. The UW team took   
   a similar approach with their bioplastics.   
      
   "This means that we would not have to redesign manufacturing lines   
   from scratch if we wanted to use our materials at industrial scales,"   
   Roumeli said. "We've removed one of the common barriers between the lab   
   and scaling up to meet industrial demand. For example, many bioplastics   
   are made from molecules that are extracted from biomass, such as seaweed,   
   and mixed with performance modifiers before being cast into films. This   
   process requires the materials to be in the form of a solution prior   
   to casting, and this is not scalable."  Other researchers have used   
   spirulina to create bioplastics, but the UW researchers' bioplastics   
   are much stronger and stiffer than previous attempts.   
      
   The UW team optimized microstructure and bonding within these bioplastics   
   by altering their processing conditions -- such as temperature, pressure,   
   and time in the extruder or hot-press -- and studying the resulting   
   materials' structural properties, including their strength, stiffness   
   and toughness.   
      
   These bioplastics are not quite ready to be scaled up for industrial   
   usage. For example, while these materials are strong, they are still   
   fairly brittle.   
      
   Another challenge is that they are sensitive to water.   
      
   "You wouldn't want these materials to get rained on," Iyer said.   
      
   The team is addressing these issues and continuing to study the   
   fundamental principles that dictate how these materials behave. The   
   researchers hope to design for different situations, by creating an   
   assortment of bioplastics. This would be similar to the variety of   
   existing petroleum-based plastics.   
      
   The newly developed materials are also recyclable.   
      
   "Biodegradation is not our preferred end-of-life scenario," Roumeli   
   said. "Our spirulina bioplastics are recyclable through mechanical   
   recycling, which is very accessible. People don't often recycle plastics,   
   however, so it's an added bonus that our bioplastics do degrade quickly   
   in the environment."  Co-authors on this paper are UW materials science   
   and engineering doctoral students Ian Campbell and Mallory Parker;   
   Paul Grandgeorge, a UW postdoctoral scholar in materials science and   
   engineering; Andrew Jimenez, who completed this work as a UW postdoctoral   
   scholar in materials science and engineering and is now at Intel;   
   Michael Holden, a UW master's student studying materials science and   
   engineering; Mathangi Venkatesh, a UW undergraduate student studying   
   chemical engineering; Marissa Nelsen, who completed this work as a UW   
   undergraduate student studying biology; and Bichlien Nguyen, a principal   
   researcher at Microsoft. This research was funded by Microsoft, Meta   
   and the National Science Foundation.   
      
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   Story Source: Materials provided by University_of_Washington. Original   
   written by Sarah McQuate. Note: Content may be edited for style and   
   length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Hareesh Iyer, Paul Grandgeorge, Andrew M. Jimenez, Ian R. Campbell,   
         Mallory Parker, Michael Holden, Mathangi Venkatesh, Marissa   
         Nelsen, Bichlien Nguyen, Eleftheria Roumeli. Fabricating Strong and   
         Stiff Bioplastics from Whole Spirulina Cells. Advanced Functional   
         Materials, 2023; DOI: 10.1002/adfm.202302067   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/07/230710132950.htm   
      
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