Separation of polyamide 66 from mixtures with cellulose fibers by selective dissolution in calcium chloride-ethanol-water solvent

Abstract

The investigation focused on the separation, through selective dissolution, of polyamide 66 (PA 66) from mixtures with cellulose fibers with calcium chloride-ethanol-water (CEW). The dissolved PA 66 was reprecipitated by addition of water. Analysis of the cellulose after separation revealed no change in mechanical strength, suggesting the polymer was undamaged by the treatment. There were residues of the polyamide retained on the cellulose, but a substantial proportion could be removed by carding. About 80–90% of the PA 66 originally present in the mixtures was recovered. Effective removal of calcium residues from the recovered PA 66 is found to be critical, as calcium contents of greater than ca. 0.8 wt% in the polymer is observed to change the melt behavior. These investigations are being conducted in the broad context of fiber-to-fiber recycling from textiles, and will be followed up by investigations on the impact and fate of colorants present in the fibers.