The role of interfacial interactions on the glass-transition and viscoelastic properties of silica/polystyrene nanocomposite

Mortezaei, Mehrzad; Famili, Mohammad Hossein Navid; Kokabi, Mehrdad

doi:10.1016/j.compscitech.2011.02.012

Cited by 66 publications

(59 citation statements)

References 32 publications

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“…18 The glass transition temperature for the nanocomposite is found to be 3 K higher, as a function of both pressure and cooling rate, than that of the neat polymer. Our small T g enhancement is consistent with other studies for silica/PS nanocomposites [19][20][21] where T g was found to increase with increasing silica fraction, although there are other studies that show no change or a T g depression. [22][23][24][25] The differences have been attributed to differences in polymer-nanoparticle interaction, preparation conditions, and dispersion morphology.…”

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confidence: 94%

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Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite

Tao

Simon

2015

J Polym Sci B Polym Phys

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The pressure-volume-temperature (PVT) behavior and glass transition behavior of a 10 wt % silica nanoparticlefilled polystyrene (PS) nanocomposite sample are measured using a custom-built pressurizable dilatometer. The PVT data are fitted to the Tait equation in both liquid and glassy states; the coefficient of thermal expansion a, bulk modulus K, and thermal pressure coefficient c are examined as a function of pressure and compared to the values of neat PS. The glass transition temperature (T g ) is reported as a function of pressure, and the limiting fictive temperature (T f 0 ) from calorimetric measurements is reported as a function of cooling rate. Comparison with data for neat PS indicates that the nanocomposite has a slightly higher T g at elevated pressures, higher bulk moduli at all pressures studied, and its relaxation dynamics are more sensitive to volume. The results for the glassy c values suggest that thermal residual stresses would not be reduced for the nanocomposite sample studied. INTRODUCTION In fiber-reinforced polymer composites, the build-up of residual stresses induced by the mismatch in thermal expansivities between filler and matrix is often inevitable during processing and application. These isotropic thermal residual stresses, which can lead to early failure or suboptimal performance of a material, depend on the thermal pressure coefficient c, which in turn depends on the product of the bulk modulus K (52V(@P/@V) T ) and the isobaric thermal expansion coefficient a p (51/V(@V/@T) P ).

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confidence: 94%

“…The relative contribution of volume and temperature to the relaxation dynamics can be examined from the ratio of the expansion coefficient at a constant relaxation time, a s 52V 21 (@V/@T) s , to the isobaric expansion coefficient a P .…”

Section: Discussionmentioning

confidence: 99%

Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite

Tao

Simon

2015

J Polym Sci B Polym Phys

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“…It is demonstrated that these excellent performances are attributed to the presence of large numbers of interphase [1,2], which is typically termed the region near the vicinity of the particles. The chain dynamics and thermodynamic properties of polymer in the interphase changed substantially due to the interactions between the nanoparticle and the polymer chains [3,4].…”

Section: Introductionmentioning

confidence: 99%

Influence of cross-linking density on the structure and properties of the interphase within supported ultrathin epoxy films

Lian

et al. 2016

J Mater Sci

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Supported polymer film models based on epoxy resin networks with four different cross-linking densities and silica substrates have been established using molecular dynamics simulations. Van der Waals forces in the form of LennardJones 9-6 are applied in calculating the interfacial interactions between the polymer and substrate. The existence of the interphase adjacent to the substrate surface was confirmed by carrying out density profile. Detailed analyses including mean square displacement and radial distribution functions of the structural properties of interphases for the four models were performed and compared. It was found that, with increasing the cross-linking density, the polymer sticks to the substrate more tightly, accompanied by stronger interactions arising from more hydrogen bonds formed between them. Furthermore, the mechanical properties of the interphase were found to be enhanced with the conversion by carrying out tensile deformation. This research regarding the interphase region within supported ultrathin epoxy films will be helpful in understanding the effect mechanism of nanofillers in the epoxy nanocomposites.

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“…It is explained by (i) formation of a stable filler network structure in polymer nanocomposites (Wang et al 2006;Su et al 2011), (ii) development of constrained regions where mobility of chains is severely restricted by surrounding clay platelets and their stacks (Zhang and Loo 2009), and (iii) overlapping of interfacial layers of neighboring nanoparticles (Mortezaei et al 2011).…”

Section: Resultsmentioning

confidence: 99%

Cyclic viscoelastoplasticity of polypropylene/nanoclay composites

Drozdov

Christiansen

2012

Mech Time-Depend Mater

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Observations are reported on isotactic polypropylene/organically modified nanoclay hybrids with concentrations of filler ranging from 0 to 5 wt.% in cyclic tensile tests with a stress-controlled program (oscillations between various maximum stresses and the zero minimum stress). A pronounced effect of nanofiller is demonstrated: reinforcement with 2 wt.% of clay results in strong reduction of maximum and minimum strains per cycle and growth of number of cycles to failure compared with neat polypropylene. To rationalize these findings, a constitutive model is developed in cyclic viscoelasticity and viscoplasticity of polymer nanocomposites. Adjustable parameters in the stress-strain relations are found by fitting experimental data. The model correctly describes the growth of the ratcheting strain and shows that fatigue failure is driven by a pronounced increase in plastic strain in the crystalline phase. To assess the influence of loading conditions on the changes in the material parameters, experimental data on polypropylene are studied in cyclic tests with a strain-controlled program (oscillations between fixed maximum and minimum strains) and a mixed program (oscillations between various maximum strains and the zero minimum stress). Numerical simulation confirms the ability of the model to predict the evolution of stress-strain diagrams with the number of cycles.

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The role of interfacial interactions on the glass-transition and viscoelastic properties of silica/polystyrene nanocomposite

Cited by 66 publications

References 32 publications

Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite

Pressure‐volume‐temperature and glass transition behavior of silica/polystyrene nanocomposite

Influence of cross-linking density on the structure and properties of the interphase within supported ultrathin epoxy films

Cyclic viscoelastoplasticity of polypropylene/nanoclay composites

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