Green and Efficient Degradation of Polyester/Cotton Blended Fabrics by Ethanolamine and Recycled Cotton and Bheta

Abstract

The improper treatment of waste polyester/cotton blended fabrics results in significant environmental pollution and resource wastage. The predominant recycling method employed is chemical recycling. However, it still presents drawbacks such as high costs, harsh reagents, and limited added value. Consequently, there is an urgent need to address the efficient treatment of waste polyester/cotton blended fabrics. The present study employs a more environmentally friendly, gentle, and energy-efficient approach known as "polyester dissolution for cotton retention" to effectively separate and recycle waste polyester/cotton blended fabrics. Firstly, the waste polyester/cotton blended fabrics are swollen using acetic acid to increase the gaps of the polyester molecular chain to facilitate contact between the polyester and the degradation solvent. Then, the polyester of the polyester/cotton blended fabrics was efficient degraded by ethanolamine and the regenerated cotton fibers were obrained after simple filtration. The effects of pretreatment condition, degradation temperature and time on the degradation efficiency of polyester under atmospheric pressure and catalyst-free conditions were investigated, and the regenerated cotton were characterized and compared with virgin cotton. Considering the comprehensive energy consumption and other factors, the optimal dissolution conditions were 40°C for 50 min. The optimal degradation conditions were 80°C degradation for 3 h, and the degradation rate of polyester reached 96.00%. The chemical structure and crystal structure of regenerated cotton is comparable to that of virgin cotton, and the tensile properties are weakened by about 0.67 N. Polyester degradation product bis(2-hydroxyethyl)terephthalamide (BHETA) can be used as a precursor for foams and adhesives. The "polyester dissolution for cotton retention" technology enables high value utilisation of waste polyester/cotton blended fabrics. The wide application of this technology is of great significance to the economy, ecological and environmental protection.

Keywords: waste polyester/cotton blended fabrics, amine degradation, regenerated cotton, "polyester dissolution for cotton retention", BHETA