Gradient of glass transition temperature in filled elastomers

Berriot, Julien; Montès, H.; Lequeux, François; Long, Didier; Sotta, Paul

doi:10.1209/epl/i2003-00124-7

Cited by 165 publications

(201 citation statements)

References 26 publications

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“…One possible explanation may be related to the kinetics of the glass transition of the amorphous part of matrix. During the cooling stage of the test as the specimen approaches the T g , polymer chains near the filler particles may be further from the equilibrium response in comparison to the unperturbed bulk chains due to the surface induced segmental immobilization [7]. Described effect may be responsible for the lower density of matrix shell surrounding silica nanoparticle core and causing the reduction of composite modulus in comparison to the K-N based prediction.…”

Section: Resultsmentioning

confidence: 97%

“…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%

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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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Section: Resultsmentioning

confidence: 97%

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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“…However, this is due to changes in the small-strain rubbery response, arising primarily from the interparticle network. Proposed immobilized rubber or glassy shell concepts [48][49][50][51][52][53][54] do not appear to have much relevance to the overall viscoelastic glass transition, at least for the two commercially important rubbers investigated in this study.…”

Section: Final Commentsmentioning

confidence: 99%

Influence of Particle Size and Polymer−Filler Coupling on Viscoelastic Glass Transition of Particle-Reinforced Polymers

et al. 2008

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The viscoelastic glass-to-rubber softening transition is analyzed for various cross-linked polymers reinforced with filler particles. We find that the loss modulus peak corresponding to the segmental relaxation process (glass transition) is not significantly affected by the particle surface area in carbon black-filled polybutadiene or by silane chemical coupling of poly(styrene-co-butadiene) to silica. Large differences in shape and magnitude of the peak in the loss tangent (tan δ) vs temperature are noted for these materials; however, this is due to variations in the storage modulus at small strains in the rubbery state, which is influenced by the nature of the jammed filler network. The use of a simple relaxation model demonstrates this feature of the viscoelastic glass transition in filled rubber. It is not necessary to invoke concepts involving a mobility-restricted polymer layer near the filler surfaces to explain the viscoelastic results. Atomic force microscopy conducted with an ultrasharp tungsten tip indicates that there may be some stiffening of the elastomer in the proximity of filler particles, but this does not translate into an appreciable effect on the segmental dynamics in these materials. IntroductionDespite significant research activity on the effect of nanoscale confinement on the glass transition temperature (T g ) of polymers, many controversial issues remain unresolved, as recently reviewed by Alcoutlabi and McKenna.1 Of particular relevance to the field of elastomers is the influence of reinforcing particles on the polymer T g . It is reasonable to expect that physical adsorption or chemical attachment of polymer chains to rigid particles can slow down the polymer dynamics, which might increase the glass transition of the polymer chains near particle surfaces. However, while some published studies show increases in T g upon the addition of carbon black, silica, or other fillers, others report no change in T g or even T g decreases.2-26 The nature of the interfacial interactions between the polymer and particles may account for some of the disparate results concerning the effect of fillers on T g .

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“…Access to this information has been gained using fluorescence resonance energy transfer 19 , quasielastic neutron scattering [20][21][22][23] , and NMR techniques [24][25][26][27][28][29] .…”

Section: Introductionmentioning

confidence: 99%

Modeling of Intermediate Structures and Chain Conformation in Silica–Latex Nanocomposites Observed by SANS During Annealing

et al. 2012

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Abstract:The evolution of the polymer structure during nanocomposite formation and annealing of silica-latex nanocomposites is studied using contrast-variation small angle neutron scattering.The experimental system is made of silica nanoparticles (R si ≈ 8 nm) and a mixture of purpose-synthesized hydrogenated and deuterated nanolatex (R latex ≈ 12.5 nm). The progressive disappearance of the latex beads by chain interdiffusion and release in the nanocomposites is analyzed quantitatively with a model for the scattered intensity of hairy latex beads and an RPA description of the free chains. In silica-free matrices and nanocomposites of low silica content (7%v), the annealing procedure over weeks at up to T g + 85 K results in a molecular dispersion of chains, the radius of gyration of which is reported.At higher silica content (20%v), chain interdiffusion seems to be slowed down on time-scales of weeks, reaching a molecular dispersion only at the strongest annealing. Chain radii of gyration are found to be unaffected by the presence of the silica filler. Tables: 5 2 Figures: 7

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Gradient of glass transition temperature in filled elastomers

Cited by 165 publications

References 26 publications

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

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

Influence of Particle Size and Polymer−Filler Coupling on Viscoelastic Glass Transition of Particle-Reinforced Polymers

Modeling of Intermediate Structures and Chain Conformation in Silica–Latex Nanocomposites Observed by SANS During Annealing

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