Optimizing Aluminum Oxyhydroxide Vapor Phase Infiltration for the Vapor Phase Mordanting of Natural Dyes to Polyester Fabrics

Abstract

Industrial textile dyeing and finishing processes are a significant environmental concern producing large quantities of wastewater that require significant treatment to remove unused synthetic chemicals. Polyester fabrics in particular utilize high temperatures and chemical carrier agents in their dyeing processes. In this work, we present a method for attaching natural dye materials derived from madder root to polyethylene terephthalate fabrics via the introduction of aluminum oxyhydroxides through vapor phase infiltration. Vapor phase infiltration (VPI) is an emerging polymer modification technique that exposes a polymer to metalorganic precursors that diffuse into the polymer and become entrapped as inorganic clusters. The resulting hybrids have unique properties of both organic and inorganic materials. The VPI process has found significant use in modifying the properties of textile materials including their mechanical and optical properties. Here, without VPI treatment, the PET fabric cannot be dyed with this natural dye. This talk will discuss how controlling the inorganic loading of hybrid AlOx-PET fabrics infiltrated with trimethylaluminum (TMA) and co-reacted with water vapor at 80 ˚C and 140 ˚C can optimize fabrics for dyeability while minimizing impact on key fabric mechanical properties. At low temperatures (80 ˚C) the resulting hybrid contains inorganic clusters not strongly bound to the polymer chain while at high temperatures (140 ˚C) the inorganic is chemically bound via the carbonyl group. Inorganic loading was controlled by varying the dose pressure of TMA (moles of TMA) and fabric mass (moles of carbonyl functional group) during VPI and quantified using thermogravimetric analysis (TGA). The resulting hybrid AlOx-PET fabrics had various inorganic loadings from one weight percent aluminum oxyhydroxide to above twenty weight percent. The hybrid fabrics were then dyed with Alizarin (derived from madder root) and the dye absorbance was quantified with UV-Vis spectroscopy. At low inorganic loadings for both temperatures, the strength of color varied with inorganic content, but a steady-state absorbance was reached at around 1.8 percent inorganic loading. At these low inorganic loadings, the hybrid fabrics maintain key mechanical behaviors such as stiffness (as measured by drape) which is seen to increase significantly with additional inorganic loading. In addition to optimizing strength of color and fabric stiffness, the time to dye saturation was also explored by varying dye times and quantifying with UV-Vis. By exploring dye saturation curves for different inorganic loadings and infiltration temperatures, kinetic information was gathered to further optimize this dyeing process for industrialization. Overall, using VPI as a vapor phase mordanting process to fix natural dyes to PET fabrics illustrates the impact that even small quantities of the vapor deposited inorganic can create enough of a base for dye to adhere to, highlighting the practical use of these fabrics in the field of textile sustainability.