In situ graft copolymerization of l-lactide onto cellulose and the direct melt spinning

Abstract

In order to prepare bio-degradable cellulose-based fibers in an environmentally-friendly way, graft copolymerization of L-lactide (LLA) onto cellulose was carried out through a co-rotating twin-screw extruder and then the blend melt was directly spun. Ionic liquid, namely 1-allyl-3-methylimidazolium chloride ([AMIM]Cl), was used as the reaction medium and tin(II) octoate was used as a catalyst. The graft copolymerization effect was evaluated by the study of FTIR, ¹³C-NMR, WAXD, TGA and SEM. The results indicated that LLA successfully in situ grafted onto the cellulose backbone and PLA long-chain branches were formed, which restrained the thermal and photo degradation of regenerated cellulose and hindered the crystallization of cellulose. The morphology of the cellulose-graft-polylactide blend fiber showed a smooth surface and ductile cross section due to the destruction of the hydrogen bond network of cellulose and the better thermoplastic properties of the PLA branches. Because cellulose-g-PLA blend with 1000 g LLA prepared at 50 rpm rotation speed has good spinnability, drawability and thermostability, the mechanical properties of this fiber were better than other cellulose-g-PLA blend fibers. Compared to other commercial cellulose fibers, the in situ graft copolymerization modification of cellulose with LLA resulted in better mechanical properties of cellulose-based fibers, high efficiency of cellulose fiber production and less energy consumption in solvent recycling.