Assessing the Washing Fastness and Environmental Impact of Various Reduction Clearing Processes on High-Performance Polyetherimide (PEI) Fabrics

PEI fibers are considered a high-performance type of fiber, known for their exceptional heat resistance and mechanical strength. These fibers, made of polyetherimide (PEI) polymer, have a completely amorphous structure, and can be dyed with disperse dyes, similar to how polyester fibers are dyed. This study focused on the reduction clearing process after dyeing PEI fibers with disperse dyes and examined various clearing agents used in both alkaline and acidic conditions, assessing how different concentrations, temperatures, and durations of reduction clearing processes affected the PEI samples. The main goal was to find the best reduction clearing parameters for disperse-dyed PEI samples, taking into account environmental impact, fabric durability, and color fastness. Analytical techniques like chemical oxygen demand (COD), biological oxygen demand (BOD 5 ), total organic carbon (TOC), and carbon footprint analysis were used for evaluation. The study revealed that most disperse-dyed PEI fibers require a reduction clearing process, with few exceptions. It is important to note that clearing with sulfuric acid-based agents or in acidic conditions may slightly reduce the fiber’s strength. On the other hand, the study identified that utilizing a solution containing 2 g/l sodium dithionite and 4 g/l NaOH for 30 min at 70 °C resulted in the least strength loss. Similarly, when considering the environmental impact, this same reduction clearing process was found to have the least detrimental effects based on COD, BOD 5 , TOC, and carbon footprint analyses. The data collection process was thoroughly documented throughout the study.