Thesis Details

Thesis Title: Evaluation of Repellent Finishes Applied by Atmospheric Plasma
Thesis Author: David Wade Tyner
Abstract: The conventional pad-dry-cure method to impart a water repellent fluoropolymer finish onto a textile has been used effectively for many years. Although this process has been very successful and is the most common method of repellent finishing, it does have disadvantages. The largest draw back to this method is that it is a wet process requiring high levels of thermal energy to evaporate the water and cure the fluoropolymer. Plasma processing can also impart a repellent finish on a textile and does not require high levels of thermal energy because there is no water to evaporate and the fluoropolymer polymerizes in the plasma therefore it does not need to be cured. Until recently, plasmas for industrial processing were only available under reduced pressure. This limited manufacturing because of the high cost of the vacuum equipment and the limitations of batch processing. Plasma processing is now available at atmospheric pressure resulting in the ability to polymerize a water repellent fluoropolymer onto the surface of a textile in a continuous full width process. This process has been successful in research labs although there has been very little research conducted on fabrics treated with industrial machinery. This research studied the repellency, durability, and cost associated with Dow Corning Plasma Solutions (DCPS) Atmospheric Pressure Plasma Liquid Deposition (APPLD) technology and the conventional pad-dry-cure method. The core objective of this project was to determine if the APPLD process could be a viable replacement for the conventional pad-dry-cure method at this current state of technology for the cotton, nylon, polyester, and polyester/cotton fabrics tested in this research. It should be noted that the fluoropolymers used in the conventional and plasma treatments are not the same and the environmental impact of the plasma treatment is not known at this time. Spray, impact, water/alcohol, oil, and contact angle tests suggested that all fabrics treated by the atmospheric plasma process exhibited equal levels of water repellency as a commercial product finished by the conventional pad-dry-cure method. Only the cotton and polyester/cotton fabrics treated by atmospheric plasma showed a decrease in repellency after multiple wash cycles when compared to the conventional finishes under identical washings. This research has also taken an in depth look at the costs associated with both the atmospheric plasma and the conventional processing methods. It has been determined that the atmospheric plasma cost associated with the fabric used in this research was $1.13 per square yard. It was also calculated that the cost to finish a square yard of the fabric by the conventional method was $0.20. Although this is a large discrepancy, a theoretical cost projection for the DCPS APPLD process in a fully engineered industrial scenario was estimated at $0.15 per square yard. The results of this research have lead to two main recommendations for future research. First, additional fabric should be run by Dow Corning at settings from which the theoretical cost calculation was based, which more accurately portrays an industrial scenario in order to determine if comparable results will be observed. Secondly, a company named APJeT should be investigated because they also have a continuous full width atmospheric plasma machine and have the following differences from Dow Corning: APJeT can recycle the helium gas used in the process, can coat different finishes on each side of the fabric, and has the ability to run faster because of a higher plasma density, leading to a projected cost per square yard of fabric of $0.10.