Thermal stability of natural dye lakes from Canadian Goldenrod and onion peel as sustainable pigments

The transformation of petrol based polymers towards more sustainable and biodegradable materials includes the development bio-based pigments for mass coloration. Dye lakes prepared from aqueous plant sources could allow a substitution synthetic with material. shaping thermoplastic melt extrusion step at higher temperature e.g. 245 °C polyamide 6, thus suitable natural dye must exhibit sufficient thermal stability. Thermogravimetric analysis differential scanning calorimetry experiments aluminium canadian goldenrod onion peel demonstrated stability up to °C. In isothermal treatment onset colour change was found near 220 °C, where only minor changes CIELab coordinates were observed. Thermally treated also tested in miniaturised dyeing using wool as substrate. Remarkably test dyeings on samples remained constant studied withstand temperatures applied polylactic acid or 6. Thus by selected renewable resources be promising greener polymers.