Polyethylene-Kevlar Composite Foams I: Morphology

Zhang, Yaolin; Rodrigue, Denis; Aı̈t-Kadi, A.

doi:10.1177/026248930302200501

Cited by 5 publications

(10 citation statements)

References 21 publications

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“…Finally, there is a densification phase when the network is collapsed onto itself and contact between network elements, which results in dramatic stiffening of the material. Although actual cell microstructure is very complicated, these regimes of deformation have been studied extensively and significant understanding has been obtained using idealized models 3–9. Currently, the quite popular theoretical model used to predict the compression properties of low density foams was put forth by Gibson and Ashby,2 which shows that in idealized cubic cell model the mechanical properties are closely relative to the foam relative densities and material properties, which is further proved by many experimental results 1, 10, 11.…”

Section: Introductionmentioning

confidence: 98%

Compressive response and energy absorption of foam EPDM

Wang

Peng

Zhang

et al. 2007

J of Applied Polymer Sci

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Ethylene-propylene-diene terpolymer foam was prepared by two different processing routes. The microstructure and mechanical properties of the foams with wide relative density ranging from 0.11 to 0.62 have been studied via scanning electron microscopy and mechanical testing, respectively. Scanning electron microscopy shows that the foam with lower relative density has a unique bimodal cell size structure, which the larger cells inlay among the smaller cells, while the foam articles with higher relative density have thicker cell walls with few small cells. The compressive stress-strain curves show that the foam articles with lower relative density have three regimes: linear elastic, a wide slightly rising plateau, and densification, while the foam articles with higher relative density have only two regimes: the longer linear elastic and densification. The relative modulus increases with the increase in the relative density. The contribution of the gas trapped in the cell to the modulus could be neglected. The energy absorbed per unit volume is relationship with the permitted stress and the relative density. The efficiency and the ideality parameter were evaluated from the compressive stress-strain plots. The parameters were plotted against stress to obtain maximum efficiency and the maximum ideality region, which can be used for optimizing the choice for practical applications in cushioning and packaging.

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Section: Introductionmentioning

confidence: 98%

Compressive response and energy absorption of foam EPDM

Wang

Peng

Zhang

et al. 2007

J of Applied Polymer Sci

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“…According to Gibson and Ashby 25 , there is a transition at a normalized density of about 0.3 between a cellular structure and one better considered as a filled composite consisting of a matrix and isolated voids. The normalized density of our composites foams are between 0.70 and 0.83, 22 so the latter case applies. Thus, for high density polymeric foams, the dependence of the modulus can be represented in terms of the mechanical properties of a two phase composites material: a solid matrix enclosing gas 'inclusions'.…”

Section: Modulus Relationship Between the Foamed And Unfoamed Compositesmentioning

confidence: 97%

“…The 3D Halpin-Tsai model still overestimates the elastic modulus because this model was developed for aligned discontinuous and oriented fibre composite, which was modified for 3D randomly, distributed fibers. In their model, the shape of inclusion is cylindrical, but the shape of our closed cell foams is mostly spherical 22 . The Gibson-Ashby model was developed for low-density foams and includes one additional parameter (φ).…”

Section: Halpin-tsai Model 34-37mentioning

confidence: 99%

“…In the first part of this study 22 , polyethylene/Kevlar PFC and MBC foams were prepared and their morphology was investigated. It was found that the foams have a nearly spherical closed cell structure but the cell sizes of MBC foams were smaller than their PFC counterparts, and the cell size distributions of MBC foams were also narrower than their PFC counterparts.…”

Section: Introductionmentioning

confidence: 99%

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Polyethylene-Kevlar Composite Foams II: Mechanical Properties

2004

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Polyethylene-Kevlar composite foams were prepared by polymerization-compounding and melt blending to investigated and understand the effect of fibers. In the first part of this study (Zhang et al., Cellular Plastics, 22, (2003), 279), we reported on the preparation and morphology of these composite foams. In this second part, the effect of fibers on the mechanical properties of composite foams is investigated. Using several models for particulate composites, it was found that the normalized modulus of our composite foams can be well predicted by the simple Moore's empirical equation to take into account the foam morphology in combination with Berlin's approach and Rosen's model for critical fiber aspect ratio to account for the effect of fibers.

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“…The materials prepared by this technique had signifi cantly improved tensile break strain compared to composites produced by standard melt blending (MBC). A review on the subject was provided in the fi rst parts of this study (3,4) .…”

Section: Introductionmentioning

confidence: 99%

Polyethylene-Kevlar Composite Foams III: Torsion Properties

Zhang

Rodrigue

2005

Cellular Polymers

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High density closed-cell Kevlar-polyethylene composite foams (17 - 30% void fraction) were prepared by compression molding and characterized via torsion rectangular tests in order to determine the effect of thin unfoamed skins and Kevlar content on shear modulus. It was found that structural foam models gave better results than uniform foam models indicating that thin skins have an important effect on the shear modulus of polymer foams. The normalized modulus of our composite structural foams can be predicted by a sandwich model in combination with Berlin's approach and Rosen's model for the aspect ratio of the fibres.

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Polyethylene-Kevlar Composite Foams I: Morphology

Cited by 5 publications

References 21 publications

Compressive response and energy absorption of foam EPDM

Compressive response and energy absorption of foam EPDM

Polyethylene-Kevlar Composite Foams II: Mechanical Properties

Polyethylene-Kevlar Composite Foams III: Torsion Properties

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