Comparison of dyeing of polyester fibers with natural dye and bio-mordant

In this study, dyeing of two regenerated polyester fibers, poly-trimethylene terephthalate (PTT) and polylactic acid (PLA), with natural dyes were compared with that of polyethylene terephthalate (PET) fiber. Lac was used as the primary natural colorant while Catechu was chosen as a natural color that can also act as a biomordant. The effects of temperature, initial pH of dye bath and dyeing time on color strength of the fibers were examined with Lac and LacCatechu combination. The results indicated the regenerated polyester fibers to have more number of functional groups and less compact structure than PET, favoring dyeing under milder conditions. PTT exhibited higher color uptake than the other fibers. Also, with Lac and Catechu in the same dye bath, the color strength was found to increase for all fibers, indicating that Catechu acted as a biomordant. Response Surface Methodology (RSM) based on 23Central Composite Design (CCD) was used for optimization of dyeing of PTT with LacCatechu combination. The optimal values for temperature, initial pH and dyeing time were found to be 127°C, 6 and 26 min, respectively. The quadratic regression model developed was found to be statistically significant using ANOVA, with R² value and adjusted R² value of 0.9708 and 0.9271 respectively.