The challenge of predicting spinnability: Investigating benefits of adding lignin to cellulose solutions in air-gap spinning

In this study, the underlying mechanism for improved spinnability when mixing lignin and cellulose in solution was investigated. Co-processing of lignin and cellulose has previously been identified as a potential route for production of inexpensive and bio-based carbon fibers. The molecular order of cellulose contributes to the strength of the fibers and the high carbon content of lignin improves the yield during conversion to carbon fibers. The current work presents an additional benefit of combining lignin and cellulose; solutions that contain both lignin and cellulose could be air-gap spun at substantially higher draw ratios than pure cellulose solutions, that is, lignin improved the spinnability. Fibers were spun from solutions containing different ratios of lignin, from 0 to 70 wt%, and the critical draw ratio was determined at various temperatures of solution. The observations were followed by characterization of the solutions with shear and elongational viscosity and surface tension, but none of these methods could explain the beneficial effect of lignin on the spinnability. However, by measuring the take-up force it was found that lignin seems to stabilize against diameter fluctuations during spinning, and plausible explanations are discussed

Tailoring the physical characteristics of solution blown cellulosic nonwovens by various post-treatments

Nonwovens are increasing in demand due to their versatility which enables use in a broad range of applications. Most nonwovens are still produced from fossil-based resources and there is thus a need to develop competitive materials from renewable feedstock. In this work, nonwovens are produced from cellulose via a direct solution blowing method. Cellulose was dissolved using the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc) and was regenerated into nonwovens by coagulation in water. The properties of such nonwovens were previously rather stiff and papery-like and the aim of this work was to improve the softness and feel of the materials by simple adjustments of the post-processing steps, i. e. washing and drying. It was shown that by primarily changing the drying method, it was possible to create a much softer and bulkier material using the same solution blowing parameters

Effects of cellulose nanofibrils on the structure and properties of maleic anhydride crosslinked poly(vinyl alcohol) electrospun nanofibers

Nanofibers of poly(vinyl alcohol) (PVA) reinforced with cellulose nanofibrils (CNFs) and/or crosslinked with maleic anhydride (MA) were produced by electrospinning technique to compare the additivation effects of the polymeric matrix. The results suggested that the PVA mass fraction equal to 14%, CNFs volumetric fraction of 3% and maleic acid at the molar ratio 20:1 are the best proportions for renewable base fibres production. In this study, the best electrospinning parameters for membranes production were obtained at the applied voltage of 24 kV, needle tip-to-collector distance of 14.5 cm, feed rate of 0.3 mL h1 and using a plate collector. CNFs and MA additions allow to improve nanofiber thermal properties and resistance to water degradation, which result in an eco-friendlier, biocompatible and long-term biodegradable nanofiber mats with diameters of 74±33 nm for water filtration purposes.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for funding the project UID/CTM/00264/2013 and A. Zille contract IF/00071/2015.info:eu-repo/semantics/publishedVersio