Permeability of Polymer/Clay Nanocomposites

2011 ◽  
Vol 1312 ◽  
Author(s):  
Georgios A. Choudalakis ◽  
Alexandros D. Gotsis
Keyword(s):  
Free Volume ◽  
Diffusion Length ◽  
Volume Fraction ◽  
Interfacial Area ◽  
Barrier Properties ◽  
Polymeric Matrix ◽  
Nanocomposite Coatings ◽  
Clay Nanocomposites ◽  
The Matrix ◽  
Diffusion Mechanisms

ABSTRACTBecause of their large interfacial area, the presence of nanoplatelets in the polymeric matrix decelerates the process of diffusion of gases through the material. The particles are impermeable barriers to the diffusing molecules, forcing them to follow complicated paths, increasing, thus, the diffusion length. The barrier properties of the nanocomposites depend on the properties of the polymeric matrix, the volume fraction of the nanoplatelets, their aspect ratio, their orientation, and their interactions with the matrix. The mobility of the molecules is hindered by the crystallinity but it is facilitated by the free volume within the material. The size and shape of the free volume holes in the polymer affect, thus, the rate of diffusion. Interactions between the nanoparticles and the matrix may lower the barrier properties because they may increase the free volume in the material. The estimation of free volume in the nanocomposite is important for the proper choice of components and the manufacturing of nanocomposite coatings with optimum barrier properties. Detailed information about the diffusion mechanisms at atomic and molecular levels can be obtained using the approach of free volume.

scholarly journals Physical-Mechanical Behavior and Water-Barrier Properties of Biopolymers-Clay Nanocomposites

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6734
Author(s):  
Heidy Lorena Calambas ◽  
Abril Fonseca ◽  
Dayana Adames ◽  
Yaneli Aguirre-Loredo ◽  
Carolina Caicedo
Keyword(s):  
Barrier Properties ◽  
Polymeric Matrix ◽  
Clay Nanocomposites ◽  
Solvent Casting ◽  
Biodegradable Films ◽  
Elongation At Break ◽  
Biodegradable Packaging ◽  
Magnetic Stirring ◽  
The Matrix

The preparation and characterization of biodegradable films based on starch-PVA-nanoclay by solvent casting are reported in this study. The films were prepared with a relation of 3:2 of starch:PVA and nanoclay (0.5, 1.0, and 1.5% w/v), and glycerol as plasticizer. The nanoclays before being incorporated in the filmogenic solution of starch-PVA were dispersed in two ways: by magnetic stirring and by sonication. The SEM results suggest that the sonication of nanoclay is necessary to reach a good dispersion along the polymeric matrix. FTIR results of films with 1.0 and 1.5% w/v of sonicated nanoclay suggest a strong interaction of hydrogen bond with the polymeric matrix of starch-PVA. However, the properties of WVP, tensile strength, percentage of elongation at break, and Young’s modulus improved to the film with sonicated nanoclay at 0.5% w/v, while in films with 1.0 and 1.5% w/w these properties were even worse than in film without nanoclay. Nanoclay concentrations higher than 1.0 w/v saturate the polymer matrix, affecting the physicochemical properties. Accordingly, the successful incorporation of nanoclays at 0.5% w/v into the matrix starch-PVA suggests that this film is a good candidate for use as biodegradable packaging.

Toughening, Thermal Stability, Flame Retardancy, and Scratch–Wear Resistance of Polymer–Clay Nanocomposites

2007 ◽  
Vol 60 (7) ◽  
pp. 496 ◽  
Author(s):  
Aravind Dasari ◽  
Szu-Hui Lim ◽  
Zhong-Zhen Yu ◽  
Yiu-Wing Mai
Keyword(s):  
Thermal Stability ◽  
Wear Resistance ◽  
Flame Retardancy ◽  
Interfacial Area ◽  
Barrier Properties ◽  
Clay Nanocomposites ◽  
Positive Effects ◽  
Large Numbers ◽  
Mechanical And Physical Properties ◽  
Wear Response

Addition of a small percent of clay to polymers improves their stiffness, strength, dimensional stability, and thermal, optical, and barrier properties. Improvements are often attributed to the availability of large numbers of clay nanolayers with tremendous interfacial area. Despite the positive effects from the addition of clay, there are unresolved issues, such as embrittlement, thermal stability, flame retardancy, scratch–wear response of the resultant nanocomposites, and/or achieving a balance between different mechanical and physical properties. In this review, we discuss these issues and the approaches that have been adopted in the expectation of resolving and understanding them, with particular emphasis on our recent and current research.

Modeling Gas Barrier Property Improvements in Polymer-Clay Nano-Composites

2014 ◽  
Vol 29 ◽  
pp. 75-84 ◽  
Author(s):  
A. Al-Abduljabbar
Keyword(s):  
High Efficiency ◽  
Volume Fraction ◽  
Barrier Properties ◽  
Two Dimensions ◽  
Clay Nanocomposites ◽  
Gas Barrier ◽  
Clay Nanoparticles ◽  
Bulk Matrix ◽  
Clay Platelets ◽  
Gas Barrier Properties

Polymer-clay nanocomposites (PCNC) offer better properties at very low volume fraction of the nanofiller compared to conventional polymer composites, thus minimizing the effect on other favored properties of the polymer. The mechanism by which clay platelets, which have thicknesses of a few nanometers in size compared with several hundred nanometers in the other two dimensions, introduce mechanical and other properties improvement can be attributed to their high efficiency in introducing a discontinuity to flows through the bulk matrix polymer material. The extent of this improvement depends on the success of intercalation or separation of the clay platelets through the bulk matrix. This paper contains a general overview of polymer-clay nanocomposites in terms of properties and processing. The improvements in gas barrier properties are discussed in detail; and a model to represent the effect of introduction of nanofillers on the permeability is proposed. The model builds on previous models to explain the improvements in the gas barrier properties due to the presence of clay nanoparticles and by assuming a proper distribution of these particles.

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

Polymers ◽  
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.

scholarly journals Physical-Mechanical Behavior and Water-Barrier Properties of Biopolymers-Clay Nanocomposites

2021 ◽  
Author(s):  
Heidy Lorena Calambas ◽  
Abril Fonseca ◽  
Dayana Adames ◽  
Yaneli Aguirre-Loredo ◽  
Carolina Caicedo
Keyword(s):  
Mechanical Properties ◽  
Barrier Properties ◽  
Clay Nanocomposites ◽  
Solvent Casting ◽  
New Materials ◽  
Vapour Permeability ◽  
Biodegradable Packaging ◽  
The Matrix ◽  
Response To Water

The preparation of new materials based on starch for the development of biodegradable packaging is increasing, however, the poor properties of this biopolymer for this application causes an area of opportunities for the improvement of water vapour permeability (WVP), mechanical properties, thermal properties, hydrophilicity, water absorption, among others. Hence, starch has been combined with other polymers such as polyvinyl alcohol, which has shown an improvement in the mechanical properties of starch, also, the use of clays suggests that the properties of response to water can be improved. Therefore, in this work, the preparation and characterization of starch-PVA-nanoclay films prepared by solvent casting is reported. The results obtained suggest that the sonication of nanoclay is necessary to reach a good dispersion, which promotes a strong interaction among starch-PVA-nanoclay. In addition, the properties of WVP and mechanical properties of films improved with incorporation of nanoclay, the concentration of 0.5% w/v of nanoclay showed to be the best concentration due to concentrations of 1.0 and 1.5% w/v were poorer than 0.5% w/v. Accordingly, the successful incorporation of nanoclays into the matrix starch-PVA suggests that this material is a good candidate for use as packaging.

Toughening of cement and other brittle solids with fibres

1983 ◽  
Vol 310 (1511) ◽  
pp. 175-190 ◽  
Keyword(s):  
Unit Volume ◽  
Volume Fraction ◽  
Interfacial Area ◽  
Theoretical Models ◽  
Brittle Solids ◽  
Final Failure ◽  
Critical Volume Fraction ◽  
The Matrix ◽  
Critical Flaw ◽  
Work Done

In common with other brittle solids, cements are toughened much more by the incorporation of fibres than by inclusions of other geometries. The largest energies required to break a specimen are found when multiple fracture of the specimen occurs before final failure. Theoretical models of a crack moving normal to a set of parallel fibres will be considered, to show that the crack spacing and first cracking strain should depend on the area of fibre-matrix interface per unit volume of composite. The first cracking strain is shown to increase for all fibre volumes provided that the fibre spacing is less than the critical flaw size according to the Griffith’s equation. The theoretical models are compared with experiment and the practical difficulties of defining first cracking strain and interfacial area mentioned. The best practical means of assessing the resistance to failure of the composite is the work done per unit volume of the specimen in separating it into two distinct pieces. The maximum values of toughness attainable - some 10 6 J m -3 - can decrease with time under external weathering, owing to continuing hydration of the matrix and consequent increase in the critical volume fraction of fibres.

scholarly journals Synergic Effect of TiO2 Filler on the Mechanical Properties of Polymer Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2017
Author(s):  
Cristina Cazan ◽  
Alexandru Enesca ◽  
Luminita Andronic
Keyword(s):  
Mechanical Properties ◽  
Polymer Nanocomposites ◽  
Polymer Matrix ◽  
Time Pressure ◽  
Volume Fraction ◽  
Interfacial Area ◽  
Polymeric Matrix ◽  
Inorganic Filler ◽  
Polymeric Nanocomposites ◽  
Technological Parameters

Nanocomposites with polymer matrix offer excellent opportunities to explore new functionalities beyond those of conventional materials. TiO2, as a reinforcement agent in polymeric nanocomposites, is a viable strategy that significantly enhanced their mechanical properties. The size of the filler plays an essential role in determining the mechanical properties of the nanocomposite. A defining feature of polymer nanocomposites is that the small size of the fillers leads to an increase in the interfacial area compared to traditional composites. The interfacial area generates a significant volume fraction of interfacial polymer, with properties different from the bulk polymer even at low loadings of the nanofiller. This review aims to provide specific guidelines on the correlations between the structures of TiO2 nanocomposites with polymeric matrix and their mechanical properties. The correlations will be established and explained based on interfaces realized between the polymer matrix and inorganic filler. The paper focuses on the influence of the composition parameters (type of polymeric matrix, TiO2 filler with surface modified/unmodified, additives) and technological parameters (processing methods, temperature, time, pressure) on the mechanical strength of TiO2 nanocomposites with the polymeric matrix.

Formation of Persistent Slip Band in Fatigued Copper Single Crystals

1982 ◽  
Vol 40 ◽  
pp. 470-471
Author(s):  
N. Y. Jin
Keyword(s):  
Volume Fraction ◽  
Fatigue Cracks ◽  
Wall Structure ◽  
Matrix Structure ◽  
Dislocation Dipole ◽  
Slip Bands ◽  
Persistent Slip Bands ◽  
The Matrix ◽  
Hard Shell ◽  
Copper Single Crystals

Localised plastic deformation in Persistent Slip Bands(PSBs) is a characteristic feature of fatigue in many materials. The dislocation structure in the PSBs contains regularly spaced dislocation dipole walls occupying a volume fraction of around 10%. The remainder of the specimen, the inactive "matrix", contains dislocation veins at a volume fraction of 50% or more. Walls and veins are both separated by regions in which the dislocation density is lower by some orders of magnitude. Since the PSBs offer favorable sites for the initiation of fatigue cracks, the formation of the PSB wall structure is of great interest. Winter has proposed that PSBs form as the result of a transformation of the matrix structure to a regular wall structure, and that the instability occurs among the broad dipoles near the center of a vein rather than in the hard shell surounding the vein as argued by Kulmann-Wilsdorf.

Preparation of Electron Transparent Metal-Matrix Composites

1968 ◽  
Vol 26 ◽  
pp. 334-335 ◽  
Author(s):  
M. R. Pinnel ◽  
A. Lawley
Keyword(s):  
Stainless Steel ◽  
Load Transfer ◽  
Volume Fraction ◽  
Steel Wire ◽  
Initial Step ◽  
Interfacial Region ◽  
Matrix Composites ◽  
Specific Test ◽  
The Matrix ◽  
The One

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.

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