MULTISCALE MODELING OF POLYMER/CLAY NANOCOMPOSITES

Multiscale molecular modeling (M3) is applied in many fields of material science, but it is particularly important in the polymer science, due to the wide range of phenomena occurring at different scales which influence the ultimate properties of the materials. In this context, M3 plays a crucial role in the design of new materials whose properties are infiuenced by the structure at nanoscale. In this work we present the application of a multiscale molecular modeling procedure to characterize polymer/clay nanocomposites obtained with full/partial dispersion of nanofillers in a polymer. This approach relies on a step-by step message-passing technique from atomistic to mesoscale to finite element level; thus, computer simulations at all scales are completely integrated and the calculated results are compared to available experimental evidences. In details, nine polymer nanocomposite systems have been studied by different molecular modeling methods, such as atomistic Molecular Mechanics and Molecular Dynamics, the mesoscale Dissipative Particles Dynamics and the macroscale Finite Element Method. The entire computational procedure has been applied to a number of diverse polymer nanocomposite systems based on montmorillonite as clay and different clay surface modifiers, and their mechanical, thermal and barrier properties have been predicted in agreement with the available experimental data.

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Rambutan peel: An unconventional source of lignin and its potential applications in polymer science

Research Society and Development ◽

10.33448/rsd-v11i1.25320 ◽

2022 ◽

Vol 11 (1) ◽

pp. e49911125320

Author(s):

Emanoel Igor da Silva Oliveira ◽

Jean Brito Santos ◽

Silvana Mattedi ◽

Nádia Mamede José

Keyword(s):

Uv Light ◽

Barrier Properties ◽

Polymer Science ◽

Ftir Analysis ◽

Ph Measurements ◽

Polymeric Matrices ◽

Wide Range ◽

Acidic Form ◽

Potential Applications ◽

Soda Lignin

This study aimed to evaluate the properties of soda lignin obtained from an unconventional and abundant waste - the rambutan peel - since lignin has been shown as the most promising natural organic feedstock alternative to petroleum for polymer science. FTIR analysis and pH measurements have confirmed the acidic form of lignin, which has shown solubility in a wide range of polarities and so many solvents, making its insertion easy on polymeric matrices. While the ability to absorb UV-light was higher than commercial lignin tested as reference, the morphology and size distribution at microscopic level were less regular than that. When added to a starch-based film, the lignin decreases its natural affinity for water, improving the barrier properties, as well as increasing its thermal resistance. Microorganisms could be developed easily on starch-based films containing this kind of lignin. This material, still underreported for technological applications, points towards as promisor to be a component or additive in polymeric matrices.

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Finite Element Analysis of Gas Diffusion in Polymer Nanocomposite Systems Containing Rod-like Nanofillers

Polymers ◽

10.3390/polym13162615 ◽

2021 ◽

Vol 13 (16) ◽

pp. 2615

Author(s):

Thouaiba Htira ◽

Sarra Zid ◽

Matthieu Zinet ◽

Eliane Espuche

Keyword(s):

Finite Element ◽

Volume Fraction ◽

Effective Diffusivity ◽

Polymer Nanocomposite ◽

Interfacial Area ◽

Barrier Properties ◽

Gas Diffusion ◽

Poly Lactic Acid ◽

Barrier Effect ◽

Element Analysis

Polymer-based films with improved gas barrier properties are of great interest for a large range of applications, including packaging and coatings. The barrier effect is generally obtained via the addition of a sufficient amount of impermeable nanofillers within the polymer matrix. Due to their low environmental footprint, bio-based nanocomposites such as poly(lactic acid)–cellulose nanocrystal (PLA–CNC) nanocomposites seem to be an interesting alternative to synthetic-polymer-based nanocomposites. The morphology of such systems consists of the dispersion of impermeable rod-like fillers of finite length in a more permeable matrix. The aim of this work is to analyze, through finite element modeling (FEM), the diffusion behavior of 3D systems representative of PLA–CNC nanocomposites, allowing the determination of the nanocomposites’ effective diffusivity. Parametric studies are carried out to evaluate the effects of various parameters, such as the filler volume fraction, aspect ratio, polydispersity, and agglomeration, on the improvement of the barrier properties. The role of the filler–matrix interfacial area (or interphase) is also investigated and is shown to be particularly critical to the overall barrier effect for highly diffusive interphases.

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Factors Affecting Molecular Self-Assembly and Its Mechanism

Scientific Research Journal ◽

10.24191/srj.v9i1.5385 ◽

2012 ◽

Vol 9 (1) ◽

pp. 43 ◽

Cited By ~ 1

Author(s):

Hueyling Tan

Keyword(s):

Self Assembly ◽

Building Blocks ◽

Molecular Engineering ◽

Molecular Structures ◽

Polymer Science ◽

New Approach ◽

Factors Affecting ◽

Dna Structures ◽

Self Assembling ◽

Wide Range

Molecular self-assembly is ubiquitous in nature and has emerged as a new approach to produce new materials in chemistry, engineering, nanotechnology, polymer science and materials. Molecular self-assembly has been attracting increasing interest from the scientific community in recent years due to its importance in understanding biology and a variety of diseases at the molecular level. In the last few years, considerable advances have been made in the use ofpeptides as building blocks to produce biological materials for wide range of applications, including fabricating novel supra-molecular structures and scaffolding for tissue repair. The study ofbiological self-assembly systems represents a significant advancement in molecular engineering and is a rapidly growing scientific and engineering field that crosses the boundaries ofexisting disciplines. Many self-assembling systems are rangefrom bi- andtri-block copolymers to DNA structures as well as simple and complex proteins andpeptides. The ultimate goal is to harness molecular self-assembly such that design andcontrol ofbottom-up processes is achieved thereby enabling exploitation of structures developed at the meso- and macro-scopic scale for the purposes oflife and non-life science applications. Such aspirations can be achievedthrough understanding thefundamental principles behind the selforganisation and self-synthesis processes exhibited by biological systems.

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Some Aspects of Parallel Implementation of the Finite Element Method on Message Passing Architectures

10.21236/ada198731 ◽

1988 ◽

Cited By ~ 2

Author(s):

I. Babuska ◽

H. C. Elman

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Message Passing ◽

Parallel Implementation ◽

The Finite Element Method ◽

Element Method

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Production of Microfibrillated Cellulose from Fast-Growing Poplar and Olive Tree Pruning by Physical Pretreatment

Applied Sciences ◽

10.3390/app11146445 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6445

Author(s):

David Ibarra ◽

Raquel Martín-Sampedro ◽

Bernd Wicklein ◽

Úrsula Fillat ◽

María E. Eugenio

Keyword(s):

Negative Impact ◽

Raw Materials ◽

Olive Tree ◽

Barrier Properties ◽

Microfibrillated Cellulose ◽

Mechanical Resistance ◽

Fast Growing ◽

Wide Range ◽

Pfi Refining ◽

Tree Pruning

Motivated by the negative impact of fossil fuel consumption on the environment, the need arises to produce materials and energy from renewable sources. Cellulose, the main biopolymer on Earth, plays a key role in this context, serving as a platform for the development of biofuels, chemicals and novel materials. Among the latter, micro- and nanocellulose have been receiving increasing attention in the last few years. Their many attractive properties, i.e., thermal stability, high mechanical resistance, barrier properties, lightweight, optical transparency and ease of chemical modification, allow their use in a wide range of applications, such as paper or polymer reinforcement, packaging, construction, membranes, bioplastics, bioengineering, optics and electronics. In view of the increasing demand for traditional wood pulp (e.g., obtained from eucalypt, birch, pine, spruce) for micro/nanocellulose production, dedicated crops and agricultural residues can be interesting as raw materials for this purpose. This work aims at achieving microfibrillated cellulose production from fast-growing poplar and olive tree pruning using physical pretreatment (PFI refining) before the microfibrillation stage. Both raw materials yielded microfibrillated cellulose with similar properties to that obtained from a commercial industrial eucalypt pulp, producing films with high mechanical properties and low wettability. According to these properties, different applications for cellulose microfibers suspensions and films are discussed.

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Nonlinear dynamic behaviour of guy cables in turbulent winds

Canadian Journal of Civil Engineering ◽

10.1139/l00-089 ◽

2001 ◽

Vol 28 (1) ◽

pp. 98-110 ◽

Cited By ~ 4

Author(s):

Bruce F Sparling ◽

Alan G Davenport

Keyword(s):

Finite Element ◽

Dynamic Behaviour ◽

Aerodynamic Drag ◽

Numerical Study ◽

Horizontal Displacement ◽

Wind Loading ◽

Second Phase ◽

Nonlinear Coupling ◽

Wide Range ◽

Cable Vibrations

Large amplitude cable vibrations are difficult to predict using linear theory due to the presence of sag in the suspended profile. A numerical study was therefore undertaken to investigate the dynamic behaviour of inclined cables excited by imposed displacements. To model the nonlinear nature of cable response, a time domain finite element approach was adopted using nonlinear catenary cable elements. Two types of horizontal displacement patterns were enforced at the upper end of the guy. In the first phase of the study, harmonic displacement histories with a wide range of forcing frequencies were considered. In the second phase, random enforced displacements were used to simulate the motion of a guyed mast in gusty winds. The influence of aerodynamic drag and damping forces was investigated by performing analyses under still air, steady wind, and turbulent wind conditions. It was found that nonlinear coupling of related harmonic response components was significant at certain critical frequencies, particular when the excitation was harmonic and acted in the plane of the guy. Positive aerodynamic damping was shown to effectively suppress resonant and nonlinear coupling response.Key words: cables, structural dynamics, wind loading, finite element method, nonlinear analysis, guyed towers.

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Local Hydrostatic Pressure Test for Cylindrical Vessels

Journal of Pressure Vessel Technology ◽

10.1115/1.4033533 ◽

2016 ◽

Vol 139 (1) ◽

Cited By ~ 1

Author(s):

H. Al-Gahtani ◽

A. Khathlan ◽

M. Sunar ◽

M. Naffa'a

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Hydrostatic Pressure ◽

Cylindrical Vessel ◽

Geometrical Parameters ◽

The Finite Element Method ◽

Wide Range ◽

Pressure Test ◽

Local Test ◽

Alternative Test

The juncture of a small cylindrical nozzle to a large cylindrical vessel is very common in the pressure vessel industry. Upon fabrication, it is required that the whole structure is subjected to pressure testing. The test can be expensive as it necessitates pressurizing the whole structure typically having a large volume. Hence, it is proposed to make a “local test,” which is considerably simpler as it involves capping the small nozzle and testing only a relatively small portion of the structure. This paper investigates the accuracy and reliability of such an alternative test, using the finite-element method. Two different finite-element types are used in the study, specifically a shell-based element and a solid-based element. The verification of the finite-element results for two different cases shows that the models used in the study are valid. It also proves that the two element types yield very similar stress results. In addition, the study includes a numerical investigation of more than 40 different nozzle-to-vessel junctures with a wide range of parameters for the nozzle and vessel. The results indicate that the use of cylindrical caps that are slightly larger than the nozzle is not recommended as it produces stresses that are significantly different from those for the original required pressure test. As such, the study provides an estimate of the smallest size of the cap that may be used in the local test to generate stresses that agree with the full test. For most practical geometries, it is shown that the size of the cap needs to be at least 2–30 times larger than that of the nozzle, depending on the geometrical parameters of the juncture.

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NOVEL COUPLING CONSTRAINT TECHNIQUE FOR EXPLICIT FINITE ELEMENT ANALYSIS

International Journal of Computational Methods ◽

10.1142/s0219876204000150 ◽

2004 ◽

Vol 01 (02) ◽

pp. 309-328

Author(s):

R. J. HO ◽

S. A. MEGUID ◽

R. G. SAUVÉ

Keyword(s):

Finite Element ◽

Current Method ◽

Explicit Integration ◽

Rotation Tensor ◽

Element Analysis ◽

Explicit Finite Element ◽

Explicit Finite Element Analysis ◽

Wide Range ◽

Large Rotations ◽

Generalized Constraint

This paper presents a unified novel technique for enforcing nonlinear beam-to-shell, beam-to-solid, and shell-to-solid constraints in explicit finite element formulations. The limitations of classical multi-point constraint approaches are examined at length, particularly in the context of explicit solution schemes. Novel formulation of a generalized constraint method that ensures proper element coupling is then presented, and its computer implementation in explicit integration algorithms is discussed. Crucial in this regard is the accurate and efficient representation of finite rotations, accomplished using an incremental rotation tensor. The results of some illustrative test cases show the accuracy and robustness of the newly developed algorithm for a wide range of deformation, including that in which large rotations are encountered. When compared to existing works, the salient features of the current method are in evidence.

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Based on Numerical Simulation of High-Performance Parallel Machine Muffler Experimental Calibration

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.718-720.1645 ◽

2013 ◽

Vol 718-720 ◽

pp. 1645-1650

Author(s):

Gen Yin Cheng ◽

Sheng Chen Yu ◽

Zhi Yong Wei ◽

Shao Jie Chen ◽

You Cheng

Keyword(s):

Numerical Simulation ◽

Finite Element ◽

Boundary Element ◽

Message Passing ◽

High Performance ◽

Message Passing Interface ◽

Parallel Machine ◽

Simulation Software ◽

Experimental Calibration ◽

The Cost

Commonly used commercial simulation software SYSNOISE and ANSYS is run on a single machine (can not directly run on parallel machine) when use the finite element and boundary element to simulate muffler effect, and it will take more than ten days, sometimes even twenty days to work out an exact solution as the large amount of numerical simulation. Use a high performance parallel machine which was built by 32 commercial computers and transform the finite element and boundary element simulation software into a program that can running under the MPI (message passing interface) parallel environment in order to reduce the cost of numerical simulation. The relevant data worked out from the simulation experiment demonstrate that the result effect of the numerical simulation is well. And the computing speed of the high performance parallel machine is 25 ~ 30 times a microcomputer.

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