Strength Enhancement of Regenerated Cellulose Fibers by Adjustment of Hydrogen Bond Distribution in Ionic Liquid

Abstract

To improve the physical strength of regenerated cellulose fibers, cellulose dissolution was analyzed with a conductor-like screening model for real solvents in which 1-allyl-3-methylimidazolium chloride (AMIMCl) worked only as a hydrogen bond acceptor while dissolving the cellulose. This process could be promoted by the addition of urea, glycerol, and choline chloride. The dissolution and regeneration of cellulose was achieved through dry-jet and wet-spinning. The results demonstrated that the addition of hydrogen bond donors and acceptors either on their own or in combination can enhance the tensile strength, but their effects on the crystallinity of the regenerated fibers were quite limited. Compared with the regenerated fibers without any additives, the tensile strength was improved from 54.43 MPa to 139.62 MPa after introducing the choline chloride and glycerol, while related the crystallinity was only changed from 60.06% to 62.97%. By contrast, a more compact structure and fewer pores on the fiber surface were identified in samples with additives along with well-preserved cellulose frameworks. Besides, it should be noted that an optimization in the overall thermal stability was obtained in samples with additives. The significant effect of regenerated cellulose with the addition of glycerol was attributed to the reduction of cellulose damage by slowing down the dissolution and cross-linking in the cellulose viscose. The enhancement of the physical strength of regenerated cellulose fiber can be realized by the appropriate adjustment of the hydrogen bond distribution in the ionic liquid system with additives.

Polymeric Wet-Strength Agents in the Paper Industry: An Overview of Mechanisms and Current Challenges

“…Regenerated cellulose fibers treated by choline chloride and glycerol ionic liquid showed a more compact structure and fewer pores on the fiber surface, along with wellpreserved cellulose frameworks compared to the untreated regenerated fibers. In addition, the tensile strength was improved from 54.43 MPa to 139.62 MPa after introducing the ionic liquid [91].…”

Recent Advances in Cellulose-Based Hydrogels Prepared by Ionic Liquid-Based Processes

“…Therefore, it has been a choice for creating regenerated cellulose hydrogels, especially in the form of fibers, because it requires less energy during the shaping process [71]. The AmimCl is also able to dissolve cellulose at a higher concentration than BmimCl [55,72], owing to its high Cl − concentration, electrochemical stability, and compatibility of hydrogen bond acceptors providing more interaction sites for hydroxyl groups of cellulose [73,74]. AmimCl is an effective IL for cellulose dissolution and hydrogel fabrication.…”

Switchable Deep Eutectic Solvents for Lignin Dissolution and Regeneration

“…All the other chemicals were obtained from the built-in database. For the COSMO-RS calculations, it was assumed that ILs were set as a mixture of an equimolar composition of cations and anions, and the DESs were set as a mixture of an equimolar composition of HBAs and HBDs [61].…”

“…However, for this specific use, it should be carefully selected to stabilize the SIL system and promote the hydrogen-bond network within. The molecular simulation was, therefore, conducted with the conductor-like screening model for real solvents (COSMO-RS), in which quantum chemical calculations were combined with statistical mechanics to explore the thermodynamic behavior of the DBU and HexOH used in this work [61]. As was previously demonstrated, charging CO 2 into SIL caused the formation of ionic SIL CO2 .…”