Skills:
- Written Communication
- Oral Communication
- IT/Technology
- Field Work
- Research Skills
- Problem Solving
- Critical Thinking
Starting in the Spring of 2023, I began doing research on biodegradable plastic alternatives in straws, using polyhydroxyalkanoates (PHAs) and comparing them to another biopolymer, polylactic acid (PLA), and conventional plastic. My research advisor, Professor John Tippett, and I were curious to see how Air Carbon PHA straws actually break down compared to how they were marketed and wanted to compare them to this other biopolymer; PLA is marketed as compostable and biodegradable, however, this is only under industrial conditions, often using incinerators as their first step.
PHA is a biopolymer that is created by bacteria in nutrient-deficient conditions that is collected and refined into a product that has the same structure as conventional plastic. It degrades from the enzyme, PHAase, in soil, marine, and aquatic bacteria.
We first decided that varying salinity was going to be our first test through our experiment. This drew us to run tests in Fredericksburg, VA (freshwater), Tappahannock, VA (oligohaline), and Norfolk, VA (mesohaline). We set up these three structures with two layers, one that floated on the surface and one that sank to the bottom of the water, to test the effects of sunlight on degradation. Each had 20 PHA, 20 PLA, and 5 conventional plastic straws, and the top rig had two mesh bags that would be collected at the end of the experiment to see if there were smaller fragmented pieces or if there was full degradation over the duration of the study. Each of the straws, after a 30-day waiting period, was collected from the top and bottom rig weekly to test the degradation rates. The mesh bags, however, were left untouched until the end of the experiment.
While this experiment was going on, we also wanted to test the degradation rates of the PHA and PLA plastics in four liquid bottles, Gatorade, vinegar, apple juice, and cola, to understand the possibility of shelf stability of these bioplastics.
Below are two images of me at our Fredericksburg site collecting the straws.
Throughout the experiment, I tracked the date the straws were collected, the number of days elapsed since it was first deployed, the location they were taken from, and a checklist of what straws were able to be collected (Image 1). If a box was not checked off, it meant that the straw had completely degraded and was not able to be collected. The next image below is the calculations that I had to make for each straw. This was set up by location, with specification of the material, and then I took the mass of each straw after finding the largest amount of the straw that was not broken down, and the length and surface area of this piece. This was to find the final mass remaining, which was compared to the bottom photograph, which was the dimensions and mass for a new straw of each material.
By collecting this data, I was able to find and graph the degradation rates, which can be seen on my final poster in my findings section. Lastly, over the last 9 months, since Feb. 2024, neither the PHA nor PLA straws have shown any degradation in our liquid bottle experiment, showing the possibility of future shelf stability of PHA plastics, and this test will be ongoing until at least my graduation in May 2025.
You can see the results and my final research poster below.
Above was the final poster that I created and presented at the 2024 Rappahannock Roundtable Symposium, the 2024 Chesapeake Watershed Forum, and the Fall Research and Creativity Showcase at the University of Mary Washington. I also had the opportunity to present a PowerPoint of my research at the Chesapeake Watershed Forum as a part of the Student Research Showcase. This can be seen below.
