Volume recovery of polystyrene: evolution of the characteristic relaxation time

Bernazzani, Paul; Simon, Sindee L.

doi:10.1016/s0022-3093(02)01463-1

Cited by 34 publications

(37 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We choose this PS as the matrix material due to the presence of considerable data from previous dilatometric and calorimetric studies by Simon and coworkers. [33][34][35][36][37][38] A 10 wt % (equivalent to 4.2 vol %) silica/PS nanocomposite was prepared using the rapid precipitation method. 39 The colloidal silica was first diluted with MEK (Sigma-Aldrich, 99.7%) at a concentration of 1 mg/mL.…”

Section: Methodsmentioning

confidence: 99%

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

Tao

Simon

2015

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

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 ).

show abstract

Section: Methodsmentioning

confidence: 99%

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

Tao

Simon

2015

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

show abstract

“…As shown in eq 2, the TNM model assumes an Arrhenius temperature dependence of relaxation time instead of generally accepted WilliamsLandell-Ferry (WLF)/Vogel-Tammann-Hess-Fulcher (VTHF) 52,53 dependence; however, for a limited temperature range around the nominal T g , the Arrhenius approximation is valid. 24,[43][44][45][46][47] In the TNM model, the evolution of the fictive temperature during a DSC heating scan after either cooling or isothermal aging is calculated by eq 3 as follows:…”

Section: Modeling Methodologymentioning

confidence: 99%

“…In addition to examining the kinetics associated with T g in these samples, the ToolNarayanswamy-Moynihan (TNM) model of structural recovery [40][41][42] is employed to allow the quantitative comparison and physical interpretation of the results. The TNM model is widely used to describe the glass transition kinetics of glassforming materials 24,[43][44][45][46][47] even though it is known to have shortcomings. 24,48 In this work, we will use it to help us quantify differences in the nonexponentiality and nonlinearity, by the parameters of b and x, in the ultrathin film and bulk samples.…”

Section: Introductionmentioning

confidence: 99%

Structural relaxation of stacked ultrathin polystyrene films

Koh

Simon

2008

J Polym Sci B Polym Phys

130

166

View full text Add to dashboard Cite

The T g depression and kinetic behavior of stacked polystyrene ultrathin films is investigated by differential scanning calorimetry (DSC) and compared with the behavior of bulk polystyrene. The fictive temperature (T f ) was measured as a function of cooling rate and as a function of aging time for aging temperatures below the nominal glass transition temperature (T g ). The stacked ultrathin films show enthalpy overshoots in DSC heating scans which are reduced in height but occur over a broader temperature range relative to the bulk response for a given change in fictive temperature. The cooling rate dependence of the limiting fictive temperature, T f 0 , is also found to be higher for the stacked ultrathin film samples; the result is that the magnitude of the T g depression between the ultrathin film sample and the bulk is inversely related to the cooling rate. We also find that the rate of physical aging of the stacked ultrathin films is comparable with the bulk when aging is performed at the same distance from T g ; however, when conducted at the same aging temperature, the ultrathin film samples show accelerated physical aging, that is, a shorter time is required to reach equilibrium for the thin films due to their depressed T g values. The smaller distance from T g also results in a reduced logarithmic aging rate for the thin films compared with the bulk, although this is not indicative of longer relaxation times. The DSC heating curves obtained as a function of cooling rate and aging history are modeled using the Tool-Narayanaswamy-Moynihan model of structural recovery; the stacked ultrathin film samples show lower b values than the bulk, consistent with a broader distribution of relaxation times.

show abstract

“…54 The TNM and similar phenomenological models have had broad success in describing many aspects of structural relaxation in amorphous materials, although their inadequacies have also been well documented. 40,41,51,[55][56][57][58] In the case of the XPCS experiments performed here, the failure of the TNM model is essentially due to the basic assumption that τ depends on the instantaneous state of the material via Tf. This is an over-simplification as it considers that a given glassy configuration can be defined by a single parameter like Tf or some macroscopic variable like specific volume or enthalpy and does not explicitly incorporate any microscopic details of the system under investigation.…”

Section: Resultsmentioning

confidence: 99%

Comparing the atomic and macroscopic aging dynamics in an amorphous and partially crystalline Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅bulk metallic glass

et al. 2017

View full text Add to dashboard Cite

2Several recent x-ray photon correlation spectroscopy works have reported an anomalous atomic dynamics in hyper-quenched metallic glasses. Here, we compare and contrast these microscopic dynamics with that found in a Zr44Ti11Ni10Cu10Be25 bulk metallic glass, prepared with a cooling rate some 6 orders of magnitude lower. In both cases, structural relaxation in the glass is governed by internal stresses, giving rise to highly compressed density correlation functions. Differently from the fast aging reported in previous studies, here the atomic dynamics displays a slow linear atomic-level aging, while not affecting the shape parameter.Traditional macroscopic phenomenological models fail to capture the temperature dependence of the microscopic structural relaxation time, suggesting a length scale dependence of the aging. Interestingly, the dynamics does not seem to be affected by the presence of a low percentage of frozen in nanocrystals and displays a temperature dependence similar to that observed in macroscopic viscosity measurements.3

show abstract

Volume recovery of polystyrene: evolution of the characteristic relaxation time

Cited by 34 publications

References 42 publications

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

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

Structural relaxation of stacked ultrathin polystyrene films

Comparing the atomic and macroscopic aging dynamics in an amorphous and partially crystalline Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅bulk metallic glass

Contact Info

Product

Resources

About

Volume recovery of polystyrene: evolution of the characteristic relaxation time

Cited by 34 publications

References 42 publications

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

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

Structural relaxation of stacked ultrathin polystyrene films

Comparing the atomic and macroscopic aging dynamics in an amorphous and partially crystalline Zr44Ti11Ni10Cu10Be25bulk metallic glass

Contact Info

Product

Resources

About

Comparing the atomic and macroscopic aging dynamics in an amorphous and partially crystalline Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅bulk metallic glass