skip to main content

This content will become publicly available on August 18, 2022

Title: Practical Online Monitoring of Ionic Liquid Fiber Welding Solvent
Ionic liquids (ILs) are becoming important solvents in commerce, but monitoring their purity and performance in industrial applications presents new challenges. Fiber welding technology utilizes ILs to mold and shape natural fibers (cotton, hemp, flax, silk, and wool) into morphologies that are typically attained only using synthetic, petroleum-based non-biodegradable plastics. The result is an atom-efficient process that up-converts fibrous substrates to value-added products and materials. A key aspect of bringing this and other IL-enabled technologies to market relies on efficient monitoring and recycling of IL-based solvents. Implementing online IL quality monitoring enhances the unit economics of these processes. Here, we characterize and report conductivity measurements, refractometry, and ATR–FTIR spectroscopy techniques for online IL monitoring during an industrial fiber welding process. The online analysis enables more efficient recycling of the IL solvent, increasing the process efficiency and product quality.
Award ID(s):
Publication Date:
Journal Name:
ACS omega
Sponsoring Org:
National Science Foundation
More Like this
  1. Computational simulations of ionic liquid solutions have become a useful tool to investigate various physical, chemical and catalytic properties of systems involving these solvents. Classical molecular dynamics and hybrid quantum mechanical/molecular mechanical (QM/MM) calculations of IL systems have provided significant insights at the atomic level. Here, we present a review of the development and application of the multipolar and polarizable force field AMOEBA for ionic liquid systems, termed AMOEBA–IL. The parametrization approach for AMOEBA–IL relies on the reproduction of total quantum mechanical (QM) intermolecular interaction energies and QM energy decomposition analysis. This approach has been used to develop parameters formore »imidazolium– and pyrrolidinium–based ILs coupled with various inorganic anions. AMOEBA–IL has been used to investigate and predict the properties of a variety of systems including neat ILs and IL mixtures, water exchange reactions on lanthanide ions in IL mixtures, IL–based liquid–liquid extraction, and effects of ILs on an aniline protection reaction.« less
  2. The theoretical promise of ionic liquids (ILs) as ‘green’ designer solvents that can be tuned to facilitate key steps of lignocellulosic biomass processing has not been fully realized due to the sheer number of possible cation–anion combinations and concerns about toxicity of this class of chemicals. Although computational methods are being applied to identify ILs with specific functions, such as dissolution of cellulose, they are not used to iteratively design new ionic liquids with the goal of simultaneously optimizing multiple criteria, such as performance and environmental safety. Here we describe a tiered computational approach to develop new ILs based onmore »mixed quantum and molecular mechanics simulations, which, combined with analysis of physicochemical properties of ILs can be used to guide structural modifications to design both better performing task-specific and safer IL analogs. The increase in computing requirements of the proposed approach over structure-based statistical models is relatively modest; yet, our approach is more robust than these models, and far less costly than highly-accurate but very demanding large-scale molecular simulations.« less
  3. Online repository: and also on: arXiv:2204.00909. Abstract: While welding of thermoplastic composites (TPCs) is a promising rivetless method to reduce weight, higher confidence in joints’ structural integrity and failure prediction must be achieved for widespread use in industry. In this work, we present an innovative study on damage detection for ultrasonically welded TPC joints with multi-walled carbon nanotubes (MWCNTs) and embedded buckypaper films. MWCNTs show promise for structural health monitoring (SHM) of composite joints, assembled by adhesive bonding or fusion bonding, through electrical resistance changes. This study focuses on investigating multifunctional films and their suitability for ultrasonic welding (USW)more »of TPCs, using two approaches: 1) MWCNT-filled polypropylene (PP) nanocomposites prepared via solvent dispersion, and 2) high conductivity MWCNT buckypaper embedded between PP films by hot pressing. Nanocomposite formulations containing 5 wt% and 10 wt% MWCNTs were synthesized using solvent dispersion method, followed by compression molding to manufacture films. The effect of MWCNT concentration on electrical and dynamic mechanical behavior of multifunctional films was examined with a Sourcemeter and Dynamic Mechanical Analyzer, and a comparison was made between 5 - 20 wt% MWCNT/PP films based on previous research. Glass fiber/polypropylene (GF/PP) composite joints were ultrasonically welded in a single lap shear configuration using buckypaper and MWCNT/PP films. Furthermore, electrical resistance measurements were carried out for joints under bending loads. It was observed that 15 wt% and 20 wt% MWCNT/PP films had higher stability and sensitivity for resistance response than embedded buckypaper and films with low MWCNT contents, demonstrating their suitability for USW and potential for SHM.« less
  4. Isothermal membrane-based air dehumidification (IMAD) is much more energy-efficient and economical than traditional air-dehumidification technologies. There are, however, no practical IMAD process technologies currently available mainly due to limitations of current membranes. Ionic liquids (ILs) are a promising air-dehumidification membrane material. Current supported IL membranes suffer from poor stability, limiting their performances. Herein, we propose new stable IL membranes, encapsulated IL membranes (EILMs) by encapsulating 1-butyl-3-methylimidazolium bromide ([C 4 MIM][Br]) into ultrathin polycrystalline UiO-66-NH 2 metal–organic framework membranes via a ship-in-a-bottle method. The stability of IL membranes is significantly enhanced due to the IL entrapped in the pore cages ofmore »UiO-66-NH 2 . The EILMs show unprecedentedly high H 2 O permeance (∼2.36 × 10 −4 mol m −2 s −1 Pa −1 ), an order of magnitude greater than that of the most permeable air-dehumidification membranes reported so far. Furthermore, the encapsulated [C 4 MIM][Br] drastically increases the H 2 O/N 2 separation factor to ∼1560, satisfying the minimally required H 2 O/N 2 separation performance for commercially viable air-dehumidification.« less
  5. Embedded fiber Bragg grating (FBG) sensors are attractive for in-situ structural monitoring, especially in fiber reinforced composites. Their implementation in metallic structures is hindered by the thermal limit of the protective coating, typically a polymer material. The purpose of this study is to demonstrate the embedding of FBG sensors into metals with the ultimate objective of using FBG sensors for structural health monitoring of metallic structures. To that end, ultrasonic additive manufacturing (UAM) is utilized. UAM is a solid-state manufacturing process based on ultrasonic metal welding that allows for layered addition of metallic foils without melting. Embedding FBGs through UAMmore »is shown to result in total cross-sectional encapsulation of the sensors within the metal matrix, which encourages uniform strain transfer. Since the UAM process takes place at essentially room temperature, the industry standard acrylate protective coating can be used rather than requiring a new coating applied to the FBGs prior to embedment. Measurements presented in this paper show that UAM-embedded FBG sensors accurately track strain at temperatures higher than 400 C. The data reveals the conditions under which detrimental wavelength hopping takes place due to non-uniformity of the load transferred to the FBG. Further, optical cross-sectioning of the test specimens shows inhibition of the thermal degradation of the protective coating. It is hypothesized that the lack of an atmosphere around the fully-encapsulated FBGs makes it possible to operate the sensors at temperatures well above what has been possible until now. Embedded FBGs were shown to retain their coatings when subjected to a thermal loading that would result in over 50 percent degradation (by volume and mass) in atmospherically exposed fiber.« less