scholarly journals Moisture uptake in nanocellulose: the effects of relative humidity, temperature and degree of crystallinity

Cellulose ◽  
2021 ◽  
Author(s):  
Mohit Garg ◽  
Varvara Apostolopoulou-Kalkavoura ◽  
Mathieu Linares ◽  
Tahani Kaldéus ◽  
Eva Malmström ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Uptake ◽  
Thermal Insulation ◽  
Cellulose Nanofibrils ◽  
Degree Of Crystallinity ◽  
Crystalline Cellulose ◽  
Moisture Uptake ◽  
Amorphous Cellulose ◽  
Hygroscopic Properties ◽  
Cellulose Nanomaterials

AbstractFoams made from cellulose nanomaterials are highly porous and possess excellent mechanical and thermal insulation properties. However, the moisture uptake and hygroscopic properties of these materials need to be better understood for their use in biomedical and bioelectronics applications, in humidity sensing and thermal insulation. In this work, we present a combination of hybrid Grand Canonical Monte Carlo and Molecular Dynamics simulations and experimental measurements to investigate the moisture uptake within nanocellulose foams. To explore the effect of surface modification on moisture uptake we used two types of celluloses, namely TEMPO-oxidized cellulose nanofibrils and carboxymethylated cellulose nanofibrils. We find that the moisture uptake in both the cellulose nanomaterials increases with increasing relative humidity (RH) and decreases with increasing temperature, which is explained using the basic thermodynamic principles. The measured and calculated moisture uptake in amorphous cellulose (for a given RH or temperature) is higher as compared to crystalline cellulose with TEMPO- and CM-modified surfaces. The high water uptake of amorphous cellulose films is related to the formation of water-filled pores with increasing RH. The microscopic insight of water uptake in nanocellulose provided in this study can assist the design and fabrication of high-performance cellulose materials with improved properties for thermal insulation in humid climates or packaging of water sensitive goods. Graphic abstract

Moisture Uptake in Nanocellulose: The Effect of Relative Humidity, Temperature and Degree of Crystallinity

2021 ◽  
Author(s):  
Mohit Garg ◽  
Varvara Apostolopoulou-Kalkavoura ◽  
Mathieu Linares ◽  
Tahani Kaldéus ◽  
Eva Malmström ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Uptake ◽  
Thermal Insulation ◽  
Cellulose Nanofibrils ◽  
Degree Of Crystallinity ◽  
Crystalline Cellulose ◽  
Moisture Uptake ◽  
Amorphous Cellulose ◽  
Hygroscopic Properties ◽  
Cellulose Nanomaterials

Abstract Foams made from cellulose nanomaterials are highly porous and possess excellent mechanical and thermal insulation properties. However, the moisture uptake and hygroscopic properties of these materials need to be better understood for their use in biomedical and bioelectronics applications, in humidity sensing and thermal insulation. In this work, we present a combination of hybrid Grand Canonical Monte Carlo and Molecular Dynamics simulations and experimental measurements to investigate the moisture uptake within nanocellulose foams. To explore the effect of surface modification on moisture uptake we used two types of celluloses, namely TEMPO-oxidized cellulose nanofibrils and carboxymethylated cellulose nanofibrils. We find that the moisture uptake in both the cellulose nanomaterials increases with increasing relative humidity (RH) and decreases with increasing temperature, which is explained using the basic thermodynamic principles. The measured and calculated moisture uptake in amorphous cellulose (for a given RH or temperature) is higher as compared to crystalline cellulose with TEMPO- and CM-modified surfaces. The high water uptake of amorphous cellulose films is related to the formation of water-filled pores with increasing RH. The microscopic insight of water uptake in nanocellulose provided in this study can assist the design and fabrication of high-performance cellulose materials with improved properties for thermal insulation in humid climates or packaging of water sensitive goods.

scholarly journals Hygroscopic behavior and chemical composition evolution of internally mixed aerosols composed of oxalic acid and ammonium sulfate

2017 ◽  
Author(s):  
Xiaowei Wang ◽  
Bo Jing ◽  
Fang Tan ◽  
Jiabi Ma ◽  
Yunhong Zhang ◽  
...  
Keyword(s):  
Growth Factors ◽  
Chemical Composition ◽  
Relative Humidity ◽  
Oxalic Acid ◽  
Ammonium Sulfate ◽  
Water Uptake ◽  
Atmospheric Environment ◽  
Dehydration Process ◽  
Hygroscopic Properties ◽  
Ammonium Hydrogen

Abstract. Although water uptake of aerosols plays an important role in the atmospheric environment, the effects of interactions between components on chemical composition and hygroscopicity of aerosols are still not well constrained. The hygroscopic properties and phase transformation of oxalic acid (OA) and mixed particles composed of ammonium sulfate (AS) and OA with different organic to inorganic molar ratios (OIRs) have been investigated by using confocal Raman spectroscopy. It is found that OA droplets first crystallize to form oxalic acid dihydrate at 77 % relative humidity (RH), and further lose crystalline water to convert into anhydrous oxalic acid around 5 % RH during the dehydration process. The deliquescence and efflorescence point for AS is determined to be 80.1 ± 1.5 % RH and 44.3 ± 2.5 % RH, respectively. The observed efflorescence relative humidity (ERH) for mixed OA/AS droplets with OIRs of 1:3, 1:1 and 3:1 is 34.4 ± 2.0 % RH, 44.3 ± 2.5 % RH and 64.4 ± 3.0 % RH, respectively, indicating the elevated OA content appears to favor the crystallization of mixed systems at higher RH. However, the partial deliquescence relative humidity (DRH) for mixed OA/AS particles with OIR of 1:3 and 1:1 is observed to occur at 81.1 ± 1.5 % RH and 77 ± 1.0 % RH, respectively. The Raman spectra of mixed OA/AS droplets indicate the formation of ammonium hydrogen oxalate (NH4HC2O4) and ammonium hydrogen sulfate (NH4HSO4) from interactions between OA and AS in aerosols after slow dehydration process in the time scale of hours, which considerably influence the subsequent deliquescence behavior of internally mixed particles with different OIRs. The mixed OA/AS particles with 3:1 ratio exhibit no deliquescence transition over the RH range studied due to the considerable transformation of (NH4)2SO4 into nonhygroscopic NH4HC2O4. Although the hygroscopic growth of mixed OA/AS droplets is comparable to that of AS or OA at high RH during the dehydration process, Raman growth factors of mixed particles after deliquescence are substantially lower than those of mixed OA/AS droplets during the efflorescence process and further decrease with elevated OA content. The discrepancies for Raman growth factors of mixed OA/AS particles between the dehydration and hydration process at high RH can be attributed to the significant formation of NH4HC2O4 and residual OA, which remain solid at high RH and thus result in less water uptake of mixed particles. These findings improve the understanding of the role of reactions between dicarboxylic acid and inorganic salt in the chemical and physical properties of aerosol particles, and might have important implications for atmospheric chemistry.

scholarly journals An investigation on hygroscopic properties of 15 black carbon (BC) from different carbon sources: Roles of organic and inorganic components

2020 ◽  
Author(s):  
Minli Wang ◽  
Yiqun Chen ◽  
Heyun Fu ◽  
Xiaolei Qu ◽  
Bengang Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Organic Carbon ◽  
Black Carbon ◽  
Water Uptake ◽  
Carbon Sources ◽  
High Relative Humidity ◽  
Gravimetric Analysis ◽  
Hygroscopic Properties ◽  
Kinetics Of

Abstract. The hygroscopic behavior of black carbon (BC) has a significant impact on global and regional climate change. However, the mechanism and factors controlling the hygroscopicity of BC from different carbon sources are not well understood. Here, we systematically measured the equilibrium and kinetics of water uptake by 15 different BC (10 herb-derived BC, 2 wood-derived BC, and 3 soot) using gravimetric water vapor sorption method combined with in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In the gravimetric analysis, the sorption/desorption equilibrium isotherms were measured under continuous-stepwise water vapor pressure conditions, while the kinetics was measured at a variety of humidity levels obtained by different saturated aqueous salt solutions. The equilibrium water uptake of the BC pool at high relative humidity (> 80 %) positively correlated to the dissolved mineral content (0.01–13.0 wt %) (R2 = 0.86, P = 0.0001) as well as the content of the thermogravimetrically analyzed organic carbon (OCTGA, 4.48–15.25 wt %) (R2 = 0.52, P = 0.002) and the alkali-extracted organic carbon (OCAE, 0.14–8.39 wt %) (R2 = 0.80, P = 0.0001). In contrast, no positive correlation was obtained with the content of total organic carbon or elemental carbon. Among the major soluble ionic constituents, chloride and ammonium were each correlated with the equilibrium water uptake at high relative humidity. Compared with the herbal BC and soot, the woody BC had much lower equilibrium water uptake, especially at high relative humidity, likely due to the very low dissolved material content and OC content. The DRIFTS analysis provided generally consistent results at low relative humidity. The kinetics of water uptake (measured by pseudo-second order rate constant) correlated to the content of OCTGA and OCAE as well as the content of chloride and ammonium at low relative humidity (33 %), but to the porosity of bulk BC at high relative humidity (94 %). This was the first study to show that BC of different types and sources has greatly varying hygroscopic properties.

scholarly journals Size-resolved aerosol water uptake and cloud condensation nuclei measurements as measured above a Southeast Asian rainforest during OP3

2011 ◽  
Vol 11 (1) ◽  
pp. 3117-3159 ◽  
Author(s):  
M. Irwin ◽  
N. Robinson ◽  
J. D. Allan ◽  
H. Coe ◽  
G. McFiggans
Keyword(s):  
Relative Humidity ◽  
Water Uptake ◽  
Radiative Forcing ◽  
Tropical Rainforest ◽  
Hydrological Cycle ◽  
Cloud Condensation Nuclei ◽  
Tropical Atmosphere ◽  
Condensation Nuclei ◽  
Hygroscopic Properties ◽  
Diameter Range

Abstract. The influence of the properties of fine particles on the formation of clouds and precipitation in the tropical atmosphere is of primary importance to their impacts on radiative forcing and the hydrological cycle. Measurements of aerosol number size distribution, hygroscopicity in both sub- and supersaturated regimes and composition were taken between March and July 2008 in the tropical rainforest in Borneo, Malaysia, marking the first study of this type in an Asian tropical rainforest. Hygroscopic growth factors (GF) at 90% relative humidity (RH) for the dry diameter range D0=32–258 nm, supersaturated water uptake behaviour for the dry diameter range D0=20–300 nm and aerosol chemical composition were simultaneously measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA), a Droplet Measurement Technologies Cloud Condensation Nuclei counter (CCNc) and an Aerodyne Aerosol Mass Spectrometer (AMS), respectively. The derived hygroscopicty parameter κ ranged from between 0.05–0.37 for the supersaturation range 0.11–0.73% compared to those between 0.17–0.37 for measurements performed at a relative humidity of 90%. In contrast, results from a study with similar methodology performed in the Amazon basin report more similar values for κ, indicating that the aerosol as measured from both sites shows similar hygroscopic properties. However, the derived number of cloud condensation nuclei (NCCN) were much higher than those measured in the Amazon, due to the higher particle number concentrations in the rainforests of Borneo. This first contrast between the two environments may be of substantial importance in describing the impacts of particles in the tropical atmosphere.

scholarly journals An investigation on hygroscopic properties of 15 black carbon (BC)-containing particles from different carbon sources: roles of organic and inorganic components

2020 ◽  
Vol 20 (13) ◽  
pp. 7941-7954
Author(s):  
Minli Wang ◽  
Yiqun Chen ◽  
Heyun Fu ◽  
Xiaolei Qu ◽  
Bengang Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Organic Carbon ◽  
Black Carbon ◽  
Water Uptake ◽  
Mineral Content ◽  
Carbon Sources ◽  
High Relative Humidity ◽  
Hygroscopic Properties ◽  
Kinetics Of

Abstract. The hygroscopic behavior of black carbon (BC)-containing particles (BCPs) has a significant impact on global and regional climate change. However, the mechanism and factors controlling the hygroscopicity of BCPs from different carbon sources are not well understood. Here, we systematically measured the equilibrium and kinetics of water uptake by 15 different BCPs (10 herb-derived BCPs, 2 wood-derived BCPs, and 3 soot-type BCPs) using a gravimetric water vapor sorption method combined with in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In the gravimetric analysis, the sorption–desorption equilibrium isotherms were measured under continuous-stepwise water vapor pressure conditions, while the kinetics was measured at a variety of humidity levels obtained by different saturated aqueous salt solutions. The equilibrium water uptake of the tested group of BCPs at high relative humidity (>80 %) positively correlated to the dissolved mineral content (0.01–13.0 wt %) (R2=0.86, P=0.0001), the content of the thermogravimetrically analyzed organic carbon (OCTGA, 4.48–15.25 wt %) (R2=0.52, P=0.002), and the content of the alkali-extracted organic carbon (OCAE, 0.14–8.39 wt %) (R2=0.80, P=0.0001). In contrast, no positive correlation was obtained with the content of total organic carbon or elemental carbon. Among the major soluble ionic constituents, chloride and ammonium were each correlated with the equilibrium water uptake at high relative humidity. Compared with the herbal BCPs and soot, the woody BCPs had much lower equilibrium water uptake, especially at high relative humidity, likely due to the very low dissolved mineral content and OC content. The DRIFTS analysis provided generally consistent results at low relative humidity. The kinetics of water uptake (measured by pseudo-second-order rate constant) correlated to the content of OCTGA and OCAE as well as the content of chloride and ammonium at low relative humidity (33 %) but to the porosity of BCPs at high relative humidity (94 %). This was the first study to show that BCPs of different types and sources had greatly varying hygroscopic properties.

scholarly journals Water uptake and chemical composition of fresh aerosols generated in open burning of biomass

2010 ◽  
Vol 10 (11) ◽  
pp. 5165-5178 ◽  
Author(s):  
C. M. Carrico ◽  
M. D. Petters ◽  
S. M. Kreidenweis ◽  
A. P. Sullivan ◽  
G. R. McMeeking ◽  
...  
Keyword(s):  
Growth Factors ◽  
Chemical Composition ◽  
Relative Humidity ◽  
Water Uptake ◽  
Particle Sizes ◽  
Differential Mobility Analyzer ◽  
Differential Mobility ◽  
Biomass Smoke ◽  
Hygroscopic Properties ◽  
Wide Range

Abstract. As part of the Fire Lab at Missoula Experiments (FLAME) in 2006–2007, we examined hygroscopic properties of particles emitted from open combustion of 33 select biomass fuels. Measurements of humidification growth factors for subsaturated water relative humidity (RH) conditions were made with a hygroscopic tandem differential mobility analyzer (HTDMA) for dry particle sizes of 50, 100 and 250 nm. Results were then fit to a single-parameter model to obtain the hygroscopicity parameter, κ. Particles in freshly emitted biomass smoke exhibited a wide range of hygroscopicity (individual modes with 0

Starch/clay aerogel reinforced by cellulose nanofibrils for thermal insulation

Cellulose ◽  
2021 ◽  
Vol 28 (6) ◽  
pp. 3505-3513
Author(s):  
Yan-Wen Zhao ◽  
Mao-Zhang Tian ◽  
Pei Huang
Keyword(s):  
Thermal Insulation ◽  
Cellulose Nanofibrils

Effect Of Moisture On The Physical Properties Of Polyimide Films

1991 ◽  
Vol 227 ◽  
Author(s):  
Rajeevi Subramanian ◽  
Michael T. Pottiger ◽  
Jacqueline H. Morris ◽  
Joseph P. Curilla
Keyword(s):  
Dielectric Constant ◽  
Steady State ◽  
Electrical Properties ◽  
Relative Humidity ◽  
Quartz Crystal ◽  
Moisture Absorption ◽  
Relative Dielectric Constant ◽  
Moisture Uptake ◽  
Polyimide Films ◽  
Effect Of Moisture

ABSTRACTMoisture absorption and its effect on electrical properties were measured for several polyimides. A Quartz Crystal Microbalance (QCM) was used to investigate the moisture absorption in BPDA/PPD, PMDA/ODA, and BTDA//ODA/MPD polyimides. The steady-state moisture uptake in polyimides as a function of relative humidity (RH) was determined by exposing film samples to successively higher RH values ranging from 10 to 85% at 25°C. The isothermal moisture absorption as a function of percent RH was found to be nearly linear for all of the polyimides studied. The effect of moisture on the electrical properties of a BPDA/PPD polyimide was also investigated. The relative dielectric constant at 25 °C was found to be a linear function of the moisture absorbed.

scholarly journals The impact of molded pulp product process on the mechanical properties of molded Bleached Chemi-Thermo-Mechanical Pulp

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Claire Dislaire ◽  
Yves Grohens ◽  
Bastien Seantier ◽  
Marion Muzy
Keyword(s):  
Mechanical Properties ◽  
Water Uptake ◽  
Process Parameters ◽  
Manufacturing Process ◽  
Water Immersion ◽  
Young Modulus ◽  
Drying Time ◽  
Mechanical Pulp ◽  
Hygroscopic Properties ◽  
The Impact

AbstractThis study was carried out using bleached softwood Chemi-Thermo-Mechanical Pulp to evaluate the influence of Molded Pulp Products’ manufacturing process parameters on the finished products’ mechanical and hygroscopic properties. A Taguchi table was done to make 8 tests with specific process parameters such as moulds temperature, pulping time, drying time, and pressing time. The results of these tests were used to obtain an optimized manufacturing process with improved mechanical properties and a lower water uptake after sorption analysis and water immersion. The optimized process parameters allowed us to improve the Young’ Modulus after 30h immersion of 58% and a water uptake reduction of 78% with the first 8 tests done.

First global assessment of modelled aerosol hygroscopicity in the context of other aerosol optical properties

2021 ◽  
Author(s):  
Maria Ángeles Burgos Simón ◽  
Elisabeth Andrews ◽  
Gloria Titos ◽  
Angela Benedetti ◽  
Huisheng Bian ◽  
...  
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Relative Humidity ◽  
Water Uptake ◽  
Chem Phys ◽  
Earth System ◽  
Aerosol Optical Properties ◽  
System Models ◽  
Earth System Models

<p>The particle hygroscopic growth impacts the optical properties of aerosols and, in turn, affects the aerosol-radiation interaction and calculation of the Earth’s radiative balance. The dependence of particle light scattering on relative humidity (RH) can be described by the scattering enhancement factor f(RH), defined as the ratio between the particle light scattering coefficient at a given RH divided by its dry value.</p><p>The first effort of the AeroCom Phase III – INSITU experiment was to develop an observational dataset of scattering enhancement values at 26 sites to study the uptake of water by atmospheric aerosols, and evaluate f(RH) globally (Burgos et al., 2019). Model outputs from 10 Earth System Models (CAM, CAM-ATRAS, CAM-Oslo, GEOS-Chem, GEOS-GOCART, MERRAero, TM5, OsloCTM3, IFS-AER, and ECMWF) were then evaluated against this in-situ dataset. Building on these results, we investigate f(RH) in the context of other aerosol optical and chemical properties, making use of the same 10 Earth System Models (ESMs) and in-situ measurements as in Burgos et al. (2020) and Titos et al. (2021).</p><p>Given the difficulties of deploying and maintaining instrumentation for long-term, accurate and comprehensive f(RH) observations, it is desirable to find an observational proxy for f(RH). This observation-based proxy would also need to be reproduced in modelling space. Our aim here is to evaluate how ESMs currently represent the relationship between f(RH), scattering Ångström exponent (SAE), and single scattering albedo (SSA). This work helps to identify current challenges in modelling water-uptake by aerosols and their impact on aerosol optical properties within Earth system models.</p><p>We start by analyzing the behavior of SSA with RH, finding the expected increase with RH for all site types and models. Then, we analyze the three variables together (f(RH)-SSA-SAE relationship). Results show that hygroscopic particles tend to be bigger and scatter more than non-hygroscopic small particles, though variability within models is noticeable. This relationship can be further studied by relating SAE to model chemistry, by selecting those grid points dominated by a single chemical component (mass mixing ratios > 90%). Finally, we analyze model performance at three specific sites representing different aerosol types: Arctic, marine and rural. At these sites, the model data can be exactly temporally and spatially collocated with the observations, which should help to identify the models which exhibit better agreement with measurements and for which aerosol type.</p><p> </p><p>Burgos, M.A. et al.: A global view on the effect of water uptake on aerosol particle light scattering. Sci Data 6, 157. https://doi.org/10.1038/s41597-019-0158-7, 2019.</p><p>Burgos, M.A. et al.: A global model–measurement evaluation of particle light scattering coefficients at elevated relative humidity, Atmos. Chem. Phys., 20, 10231–10258, https://doi.org/10.5194/acp-20-10231-2020, 2020.</p><p>Titos, G. et al.: A global study of hygroscopicity-driven light scattering enhancement in the context of other in-situ aerosol optical properties, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2020-1250, in review, 2020.</p>

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