scholarly journals Moisture Absorption in Polymer Composites Reinforced with Vegetable Fiber: A Three-Dimensional Investigation via Langmuir Model

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1847 ◽  
Author(s):  
Brito ◽  
Santos ◽  
Correia ◽  
Queiroz ◽  
Tavares ◽  
...  
Keyword(s):  
Moisture Content ◽  
Polymer Composites ◽  
Layer Thickness ◽  
Moisture Absorption ◽  
Three Dimensional ◽  
Water Concentration ◽  
Langmuir Model ◽  
Sisal Fiber ◽  
Average Moisture Content ◽  
Material Surface

This work aims to study numerically the moisture absorption in polymer composite reinforced with vegetable fibers using the Langmuir model which considers the existence of free and entrapped water molecules inside the material. A three-dimensional and transient modeling for describing the water absorption process inside the composite and its numerical solution via finite volume method were presented and discussed. Application has been made for polymer composites reinforced with sisal fiber. Emphasis was given to the effect of the layer thickness of fluid close to the wall of the composite in the progress of water migration. Results of the free and entrapped solute (water) concentration, local moisture content and average moisture content, at different times of process, and inside the composite were presented and analyzed. It was verified that concentration gradients of the molecules (free and entrapped) are higher in the material surface, at any time of the process, and concentration of free solute is greater than the concentration of entrapped solute. It was verified that the water layer thickness surrounding the composite strongly affects the moisture absorption rate.

Drying of Sisal Fiber: Three-Dimensional Mathematical Modeling and Simulation

2020 ◽  
Vol 399 ◽  
pp. 202-207
Author(s):  
Jaqueline Félix de Brito Diniz ◽  
Gicélia Moreira ◽  
José Jefferson da Silva Nascimento ◽  
Rodolfo Pereira de Farias ◽  
Hortência Luma Fernandes Magalhães ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Experimental Data ◽  
Mass Transfer ◽  
Moisture Content ◽  
Three Dimensional ◽  
Sisal Fiber ◽  
Average Moisture Content ◽  
Proposed Model ◽  
Volume Method ◽  
Good Agreement

This work presents a theoretical drying study of sisal fiber. Fibers with moisture content of around 11.2% were dried in an oven in the temperature 90°C. A transient and three-dimensional mathematical modeling to predict heat and mass transfer in a bed of fiber was proposed and numerically solved by using the finite-volume method. Results of the average moisture content and surface temperature were compared with experimental data to verify the consistence of the proposed model, and good agreement was verified.

Heat and Mass Diffusion Including Shrinkage and Hygrothermal Stress during Drying of Holed Ceramics Bricks

2011 ◽  
Vol 312-315 ◽  
pp. 971-976 ◽  
Author(s):  
J. Barbosa da Silva ◽  
G. Silva Almeida ◽  
W.C.P. Barbosa de Lima ◽  
Gelmires Araújo Neves ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Moisture Content ◽  
Three Dimensional ◽  
Average Moisture Content ◽  
Stress Distributions ◽  
Drying Process ◽  
Convective Boundary ◽  
Volume Method ◽  
Hygrothermal Stress ◽  
Thermo Physical Properties ◽  
Good Agreement

The Aim of this Work Is to Present a Three-Dimensional Mathematical Modelling to Predict Heat and Mass Transport inside the Industrial Brick with Rectangular Holes during the Drying Including Shrinkage and Hygrothermalelastic Stress Analysis. the Numerical Solution of the Diffusion Equation, Being Used the Finite-Volume Method, Considering Constant Thermo-Physical Properties and Convective Boundary Conditions at the Surface of the Solid, it Is Presented and Analyzed. Results of the Temperature, Moisture Content and Stress Distributions, and Drying and Heating Kinetics Are Shown and Analyzed. Results of the Average Moisture Content and Surface Temperature of the Brick along the Drying Process Are Compared with Experimental Data (T = 80.0oC and RH = 4.6 %) and Good Agreement Was Obtained. it Was Verified that the Largest Temperature, Moisture Content and Stress Gradients Are Located in the Intern and External Vertexes of the Brick.

scholarly journals Non-Fickian Moisture Transport in Vegetable-Fiber-Reinforced Polymer Composites Using a Langmuir-Type Model

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2503
Author(s):  
Rafaela Q. C. Melo ◽  
Marcus V. Lia Fook ◽  
Antonio G. B. de Lima
Keyword(s):  
Moisture Content ◽  
Water Absorption ◽  
Polymer Composites ◽  
Layer Thickness ◽  
Water Layer ◽  
Fiber Reinforced Polymer ◽  
Type Model ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites ◽  
Vegetable Fiber

The purpose of this article was to theoretically study the non-Fickian moisture absorption process in vegetable-fiber-reinforced polymer composites using a Langmuir-type model. Here, the focus was on evaluating the effect of the water layer thickness that surrounds the composite during the water migration process. The solutions of the governing equations were obtained using the finite volume method, considering constant thermophysical properties and non-deformable material. The results for the local and average moisture content and concentration, gradient values, and the transient rates of the free and bound (water) molecules in the process were presented and analyzed. It was observed that the water layer thickness strongly influenced the water absorption kinetics, the moisture content gradient values, and the equilibrium moisture content inside the material. It is envisaged that this new approach will contribute to better interpretation of experimental data and a better understanding of the physical phenomenon of water absorption, which directly affects the properties of composite materials.

Water Absorption in Composites Reinforced with Caroá Fiber Fabrics: Modeling and Simulation via ANSYS CFX®

2014 ◽  
Vol 353 ◽  
pp. 84-89 ◽  
Author(s):  
C.J. Silva ◽  
T.H.F. de Andrade ◽  
E.G. Silva ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Moisture Content ◽  
Water Absorption ◽  
Moisture Absorption ◽  
Natural Fiber ◽  
Unsaturated Polyester ◽  
Fiber Reinforced Composites ◽  
Synthetic Fiber ◽  
Average Moisture Content ◽  
Reinforced Composites ◽  
Fiber Reinforced

Studies in polymer composites reinforced with vegetable fiber show that they are enough sensitive to influences from environmental agents such as water and temperature. The moisture causes degradation of the mechanical properties of natural fiber reinforced composites to a large extent when compared to synthetic fiber reinforced composites. This is a consequence of the higher moisture absorption, and the hydrofilic nature of the natural fiber. In this sense, the purpose of this work is to study theoretically the water absorption in unsaturated polyester composites reinforced with caroá natural fiber (Neoglazioviavariegata) at the temperature 50°C. The composite had a weight composition of 30% caroá and 70% unsaturated polyester resin and dimensions of 20× 20× 3 mm3. Results of the average moisture content and moisture content distribution during the absorption process are presented and analyzed. Comparison between numerical and experimental data of the average moisture content presented good agreement. We conclude that the water absorption rate is faster in the vertex region of the composites.

scholarly journals Mapping barrier island soil moisture using a radiative transfer model of hyperspectral imagery from an unmanned aerial system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rehman S. Eon ◽  
Charles M. Bachmann
Keyword(s):  
Soil Moisture ◽  
Radiative Transfer ◽  
Moisture Content ◽  
Layer Thickness ◽  
Soil Moisture Content ◽  
Hyperspectral Imagery ◽  
Barrier Island ◽  
Water Layer ◽  
Radiative Transfer Model ◽  
Transfer Model

AbstractThe advent of remote sensing from unmanned aerial systems (UAS) has opened the door to more affordable and effective methods of imaging and mapping of surface geophysical properties with many important applications in areas such as coastal zone management, ecology, agriculture, and defense. We describe a study to validate and improve soil moisture content retrieval and mapping from hyperspectral imagery collected by a UAS system. Our approach uses a recently developed model known as the multilayer radiative transfer model of soil reflectance (MARMIT). MARMIT partitions contributions due to water and the sediment surface into equivalent but separate layers and describes these layers using an equivalent slab model formalism. The model water layer thickness along with the fraction of wet surface become parameters that must be optimized in a calibration step, with extinction due to water absorption being applied in the model based on equivalent water layer thickness, while transmission and reflection coefficients follow the Fresnel formalism. In this work, we evaluate the model in both field settings, using UAS hyperspectral imagery, and laboratory settings, using hyperspectral spectra obtained with a goniometer. Sediment samples obtained from four different field sites representing disparate environmental settings comprised the laboratory analysis while field validation used hyperspectral UAS imagery and coordinated ground truth obtained on a barrier island shore during field campaigns in 2018 and 2019. Analysis of the most significant wavelengths for retrieval indicate a number of different wavelengths in the short-wave infra-red (SWIR) that provide accurate fits to measured soil moisture content in the laboratory with normalized root mean square error (NRMSE)< 0.145, while independent evaluation from sequestered test data from the hyperspectral UAS imagery obtained during the field campaign obtained an average NRMSE = 0.169 and median NRMSE = 0.152 in a bootstrap analysis.

scholarly journals Study on the Moisture Absorption and Thermal Properties of Hygroscopic Exothermic Fibers and Related Interactions with Water Molecules

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 98 ◽  
Author(s):  
Yi Cui ◽  
Shuyi Gao ◽  
Ruiyun Zhang ◽  
Longdi Cheng ◽  
Jianyong Yu
Keyword(s):  
Moisture Content ◽  
Thermal Performance ◽  
Water Sorption ◽  
Moisture Absorption ◽  
Bound Water ◽  
Absorption Process ◽  
Heating Performance ◽  
Hygroscopic Behavior ◽  
Water Sorption Capacity ◽  
Main Factor

The aim of this paper is to study the hygroscopic behavior of hygroscopic exothermic fiber-based materials and to obtain a better understanding of the thermal performance of these fibers during the moisture absorption process. The temperature distribution of different kinds of hygroscopic exothermic fibers in the process of moisture absorption, observed by infrared camera, demonstrated two types of heating performance of these fibers, which might be related to its hygroscopic behavior. Based on the sorption isotherms, a Guggenheim-Anderson-de Boer (GAB) multi-layer adsorption model was selected as the optimal moisture absorption fitting model to describe the moisture absorption process of these fibers, which illustrated that water sorption capacity and the water–fiber/water–water interaction had a significant influence on its heating performance. The net isosteric heats of sorption decreased with an increase of moisture content, which further explained the main factor affecting the heat dissipation of fibers under different moisture contents. The state of adsorbed water and water vapor interaction on the fiber surface were studied by simultaneous thermal analysis (TGA-DSC) measurement. The percentage of bound and unbound water formation at low and high humidity had a profound effect on the thermal performance of fibers. It can therefore be concluded that the content of tightly bound water a strong water–fiber interaction was the main factor affecting the heating performance of fibers at low moisture content, and the content of loosely bound water reflected that water sorption capacity was the main factor affecting the heating performance of fibers at high moisture content. This was further proven by the heat of desorption.

scholarly journals Titanium oral implants: surface characteristics, interface biology and clinical outcome

2010 ◽  
Vol 7 (suppl_5) ◽  
Author(s):  
Anders Palmquist ◽  
Omar M. Omar ◽  
Marco Esposito ◽  
Jukka Lausmaa ◽  
Peter Thomsen
Keyword(s):  
Surface Properties ◽  
Cellular Response ◽  
Randomized Clinical Trials ◽  
Three Dimensional ◽  
Cell Communication ◽  
Surface Characteristics ◽  
Titanium Implants ◽  
Material Surface ◽  
Oral Implants

Bone-anchored titanium implants have revolutionized oral healthcare. Surface properties of oral titanium implants play decisive roles for molecular interactions, cellular response and bone regeneration. Nevertheless, the role of specific surface properties, such as chemical and phase composition and nanoscale features, for the biological in vivo performance remains to be established. Partly, this is due to limited transfer of state-of-the-art preparation techniques to complex three-dimensional geometries, analytical tools and access to minute, intact interfacial layers. As judged by the available results of a few randomized clinical trials, there is no evidence that any particular type of oral implant has superior long-term success. Important insights into the recruitment of mesenchymal stem cells, cell–cell communication at the interface and high-resolution imaging of the interface between the surface oxide and the biological host are prerequisites for the understanding of the mechanisms of osseointegration. Strategies for development of the next generation of material surface modifications for compromised tissue are likely to include time and functionally programmed properties, pharmacological modulation and incorporation of cellular components.

Sign in / Sign up

Export Citation Format

Share Document