Viscoelastic response of nanocomposite poly(vinyl acetate)‐hydroxyapatite with varying particle shape—Dynamic strain softening and modulus recovery

Kalfus, Jan; Jančář, J.

doi:10.1002/pc.20331

Cited by 29 publications

(32 citation statements)

References 15 publications

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“…This can be attributed to the chain immobilization in the vicinity of filler surfaces, which is consistent with results published in literature [11,[13][14][15]. It was also demonstrated that the particle size affects thermal stability of the Mg(OH) 2 filled EVA significantly.…”

Section: Discussionsupporting

confidence: 91%

“…Dolan [12] demonstrated that inorganic powder can suppress the methane burning with the magnitude of the effect proportional to the particle specific surface area. As it has already been shown by Kalfus and Jancar [13][14][15], filler nanoparticles may cause considerable immobilization effects in the polymer matrix even in the case of weak filler-particle interaction. As a consequence, one can observe sharp enhancement of composite elastic modulus.…”

Section: Introductionmentioning

confidence: 87%

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Effect of Particle Size on the Thermal Stability and Flammability of Mg(OH)2/EVA Nanocomposites

Kalfus

Jančář

2010

Composite Interfaces

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The effect of the Mg(OH) 2 particle size on the thermal degradation and flammability of a model nanocomposite is presented. In order to investigate the effect of particle size on the flammability and thermal stability of materials intended for cable coatings, the ethylene-vinyl acetate copolymer (EVA) was filled with two types of magnesium hydroxide (Mg(OH) 2 ) with the average particle size 20 nm and 2000 nm. The thermogravimetric experiments performed under nitrogen and air atmosphere did not reveal any substantial effect of particle size on the mechanisms and kinetics of Mg(OH) 2 decomposition. Both types of Mg(OH) 2 , at temperatures above 350 • C, decomposed endothermally to MgO and H 2 O. At the same filler volume fraction, composites with the larger Mg(OH) 2 particles exhibited greater value of the limiting oxygen index (LOI) compared to Mg(OH) 2 nanocomposites. It is proposed that the reduction of Mg(OH) 2 particle size below 200 nm results in the catalytic effect of Mg 2+ to become more prominent compared to coarser particles. In the case of nano-sized Mg(OH) 2 , a large portion of polymer matrix is in direct contact with filler surface due to the high specific surface area of the filler used. Large filler-matrix contact area most probably resulted in the surface-induced catalytic effects of the Mg 2+ ion on degradation of polyolefins, already described in the literature, accelerating thermal degradation of EVA matrix. This process acts against the flame retarding effect of the Mg(OH) 2 thermal decomposition. Furthermore, larger filler surface of nano-filler led to the indispensable change of the deformation response of EVA compared to the micro-filled composite.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 87%

Effect of Particle Size on the Thermal Stability and Flammability of Mg(OH)2/EVA Nanocomposites

Kalfus

Jančář

2010

Composite Interfaces

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“…There is a large literature showing a strong softening of NP-filled networks where the effect is temperature dependent and where the effect is observed following a small extent of deformation. The Payne effect is often attributed to the breakdown of particle-polymer associations within the network,68 as in our model, or the irreversible breakup of NP clusters within the network. The breakup of the physical associations should be reversible while this is not the case for the breakup of the NP clusters.…”

Section: Resultsmentioning

confidence: 82%

Development of minimal models of the elastic properties of flexible and stiff polymer networks with permanent and thermoreversible cross-links

2010

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We review the elasticity of flexible and stiff polymer networks with permanent cross-links and synthesize these results into a unifying polymer chain network model. This framework is then used to address how the network elasticity becomes modified when the network cross-linking is thermoreversible in nature, changes in the stability of the network with deformation, and the effect of a variable rate of network deformation on the non-linear elastic response. Comparisons are made between this class of simplified network models with elasticity measurements performed on flexible chain and stiff fiber networks, both with permanent and associative cross-links. Although these network models are highly idealized, they are apparently able to capture many aspects of the elastic properties of diverse real networks.

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“…So far, serious attempts to investigate the reinforcing mechanism in polymer nanocomposites have been predominantly restricted to systems with amorphous matrices [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In these matrices above their T g , the chains can undergo segmental immobilization induced even by weak interactions on the large filler-matrix internal interface.…”

Section: Introductionmentioning

confidence: 99%

Effect of weakly interacting nanofiller on the morphology and viscoelastic response of polyolefins

Kalfus

Jančář

Kučera

2008

Polymer Engineering & Sci

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Effect of silica nanofiller on the deformation response and morphology of low-and high-density polyethylene (HDPE, LDPE) and isotactic polypropylene (PP) modified with fumed silica was investigated. The dynamicmechanical thermal spectroscopy, differential scanning calorimetry, optical microscopy, and density measurements were carried out to determine the temperature dependence of storage and loss moduli as well as nanocomposite morphology. It was demonstrated that the degree of matrix reinforcement is considerably affected by the extent of matrix crystallinity, especially, in the temperature range from (T m -1308C) to T m . Based on experimental evidence and literature review, it is proposed that this phenomenon may be attributed to the alpha-mechanical relaxation process occurring above matrix T g . As a result of adding silica into the melted matrix, mobility of chains in contact with silica particles became reduced. This caused substantial changes in morphology of these semicrystalline nanocomposites.

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Viscoelastic response of nanocomposite poly(vinyl acetate)‐hydroxyapatite with varying particle shape—Dynamic strain softening and modulus recovery

Cited by 29 publications

References 15 publications

Effect of Particle Size on the Thermal Stability and Flammability of Mg(OH)2/EVA Nanocomposites

Effect of Particle Size on the Thermal Stability and Flammability of Mg(OH)2/EVA Nanocomposites

Development of minimal models of the elastic properties of flexible and stiff polymer networks with permanent and thermoreversible cross-links

Effect of weakly interacting nanofiller on the morphology and viscoelastic response of polyolefins

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