High modulus regenerated cellulose fibers spun from a low molecular weight microcrystalline cellulose solution

Abstract

We have developed a novel process to convert low molecular weight microcrystalline cellulose into stiff regenerated cellulose fibers using a dry-jet wet fiber spinning process. Highly aligned cellulose fibers were spun from optically anisotropic microcrystalline cellulose/1-ethyl-3-methylimidazolium diethyl phosphate (EMImDEP) solutions. As the cellulose concertation increased from 7.6 wt% to 12.4 wt%, the solution texture changed from completely isotropic to weakly nematic. Higher concentration solutions (>15 wt%) showed strongly optically anisotropic patterns, with clearing temperatures ranging from 80 °C to 90 °C. Cellulose fibers were spun from 12.4 wt%, 15.2 wt% and 18.0 wt% cellulose solutions. The physical properties of these fibers were studied by Scanning Electron Microscopy (SEM), Wide Angle X-ray Diffraction (WAXD) and tensile testing. The 18.0 wt% cellulose fibers, with an average diameter of ~20 μm, possessed high Young’s modulus up to ~22 GPa, moderately high tensile strength of ~305MPa, as well as high alignment of cellulose chains along the fiber axis confirmed by X-ray diffraction. This process presents a new route to convert microcrystalline cellulose, which is usually used for low mechanical performance applications (matrix for pharmaceutical tablets and food ingredients, etc.) into stiff fibers which can potentially be used for high performance composite materials.