No abstract

A sustainable and hydrolysis-free dyeing process was developed for polylactic acid (PLA) fibers. PLA is a biobased alternative to petroleum based polyethylene terephthalate (PET), which is the most widely used textile fiber. However, the hydrolytic degradation of PLA fibers under the conventional aqueous dyeing conditions limited its applications in textile industry. A new solvent dyeing process was developed using liquid paraffin as a nonaqueous dyeing medium. High quality dyed PLA fabrics were obtained without consuming water and auxiliaries. Minimal strength loss of dyed fibers was achieved by postheat setting treatment. The 3R principle (reduce, reuse, and recycle) was implemented to ensure the environmental friendliness of solvent dyeing process. The result of a 9-cycle reuse sequence demonstrated excellent color consistency of dyed PLA fabrics. The sustainability of our new dyeing process was quantified in the framework of environmental-health-social impact. The dyeing process sustainability index indicated that the solvent dyeing process was preferred over the aqueous dyeing. The method developed in the present work enabled the practical applications of PLA as textile fibers. It represented an important step toward a sustainable textile industry.

Lignin has received significant attention as a waste product from industrial and agricultural processing, yet technical lignins are typically low in phenolic contents and its use scenarios are still largely limited. Herein, we report highly phenolic lignin nanoparticles (HP-LNPs) obtained by alkaline treatments followed by a enzymatic treatment using laccase. Urea and H 2 O 2 were used in the alkaline treatments to enhance the LNPs with antioxidant properties and to cut down the absorption in the visible range. As a result, the HP-LNPs (N-U-L-lignin) exhibited excellent antioxidant properties, with scavenging rates of 76.12 ± 5.64% and 51.50 ± 4.26% for DPPH and PTIO radicals, respectively. The whiteness value of the HP-LNPs (N-H-L-lignin) increased from 43.50 to 56.39, thereby qualifying them as a natural anti-UV filler in sunscreens. We have also demonstrated, for the first time, that LNPs can be directly used for food preservation: the shelf life of fruits, such as bananas, was extended by 7 days.