Discipline: Technology and Engineering
Subcategory: Chemical/Bimolecular/Process Engineering
Room: Exhibit Hall
Sarah Kelley - The University of Alabama
Co-Author(s): Stephen M.C. Ritchie, Ph.D., The University of Alabama, Tuscaloosa, AL; Shaun Sprinkle, The University of Alabama, Tuscaloosa, AL; Robert Scott, The University of Alabama, Tuscaloosa, AL
Hypothesis statement: Suitable landscape fabric can be made from up-cycled polypropylene (PP) fibers that will be as effective as commercial fabric. The surface chemistry of the fabric can be altered to promote the adsorption of a hydrophilic fungicide coating. The coating will act as a controlled release fungicide that will leach into the soil as rain and watering break it down. At the end of the season, the fabric can be recovered and the fungicide coating reloaded.Fungicides contribute to thirty-five percent of the pesticide market share worldwide. Those in liquid form pose issues, including risks for aquatic ecosystems and mild to severe reactions within humans who come into direct contact. A solid phase, controlled-release fungicide reduces the required dose and limits human exposure.Methods and control: Recycled PP was melt-spun using a steel rod to draw fibers from molten plastic. The fibers were then laid onto aluminum sheets, and hot pressed to form a non-woven material. Commercial landscaping fabric made from virgin PP and a PP non-woven backing were used as controls. All materials were tested for air and water permeability. In addition, dog bone-shaped samples were prepared to measure tensile strength. Finally, the sample was coated by thermal polymerization of sodium styrene sulfonate. The successful coating was confirmed by dye testing with Methylene Blue and comparison with an unaltered control sample.Results: Our tests produced several different outcomes. The landscape fabric control had negligible resistance to airflow. The PP non-woven control had ten percent lower air permeance than the landscape fabric, and our hot press samples showed about twenty percent lower air permeance than the landscape fabric. This was probably due to the larger fiber diameter and high density. There was no significant difference in water permeabilities between any of the materials. Using the Instron to test tensile strength, we found that our samples had the highest strains and stretched at least two times their initial length. The PP non-woven control was the stiffest and had the highest Young’s Modulus. The result after we altered the surface chemistry of our sample was positive. The altered sample showed dye uptake, and the unaltered did not. This showed that we successfully altered the surface chemistry to be charged and more hydrophilic. Conclusions and future research questions: After evaluating the data from our tests, we concluded that a suitable landscape fabric can be made from up-cycled polypropylene and that the surface chemistry can be altered to be charged and more hydrophilic. Future work would include adding a fungicide to the coating and evaluating the controlled release of fungicide to the soil targeting the fungus Phytophthora cactorum, which causes harm to strawberry crops. Also, tests would be done to see how effectively the fabric can be recovered, reloaded, and reused for another garden season.
Funder Acknowledgement(s): National Science Foundation
Faculty Advisor: Stephen M.C. Ritchie, Ph.D. Chemical & Biological Engineering, The University of Alabama, Tuscaloosa, AL, firstname.lastname@example.org
Role: I developed the method for drawing fibers out of the polypropylene melt. I then tested different wet-lay methods to stabilize the fibers before bonding in a hot press. The hot press overpressed our first samples, so I devised a way to keep the machine from overpressing. I then worked with my REU student mentor to test the water and air permeability. We also worked with faculty from MTE to test the stress/strain of our samples. Lastly, I worked with a graduate student to thermally coat our non-woven sample with the negatively charged polymer. The graduate student dye-tested the material.