Triboelectric properties of recycled poly(ethylene terephthalate) nanofibrous web from waste clothes

This study systematically investigates how different DCM-to-TFA solvent ratios influence the properties of electrospun PET nanofibrous webs, including solubility, morphology, chemical composition, mechanical behavior, and triboelectric performance. Solubility tests showed that PET dissolves poorly (<70 %) under pure DCM conditions (10:0), whereas ratios with less than 90 % DCM (9:1-0:10) achieved over 80 % dissolution. As the TFA fraction increased, the average fiber diameter dropped from about 1.0 mu m (9:1) to below 0.5 mu m (1:9, 0:10), and FT-IR spectra (notably in the 1300-1600 cm(-1)) revealed partial azo dye decomposition. XRD analysis indicated predominantly amorphous structures at low TFA content, transitioning to more crystalline domains when TFA was equal to or exceeded DCM, notably around a 5:5 ratio. This increase in crystallinity strengthens intermolecular interactions and contributes to improved mechanical behavior; indeed, the Young's modulus reached approximately 1.8 MPa under these conditions. Although triboelectric outputs generally remained in the millivolt range, the highest (similar to 70 mV) were observed at 5:5 and 3:7, then dropped to about 30 mV with excessive TFA-likely due to over-decomposition of the dye and polymer, which can hinder efficient charge generation pathways. Notably, this approach demonstrates that strong mechanical and triboelectric properties can be realized without fully removing or degrading both the dye and PET, thereby reducing process complexity by omitting separate decolorization or high-temperature treatments. Further work to quantify dye decomposition and assess long-term stability could advance the industrial feasibility of these sustainable, high-value recycled PET materials. Moreover, by leveraging the residual dyes inherently present in recycled PET garments-rather than removing them-we simplify the dye-separation process and discover new avenues for resource-efficient, triboelectric nanofibrous materials.