The glass transition temperature versus the fictive temperature

Badrinarayanan, Prashanth; Zheng, Wei; Li, Qingxiu; Simon, Sindee L.

doi:10.1016/j.jnoncrysol.2007.04.025

Cited by 224 publications

(220 citation statements)

References 43 publications

Supporting

Mentioning

195

Contrasting

Order By: Relevance

“…As mentioned in the methodology section, the standard deviation in the T g values is considered to be 1.5 8C based on the standard deviation of five isobaric cooling runs performed at 60.7 MPa. Our results are consistent with the T g value measured at atmospheric pressure using capillary dilatometry for the same Dylene 8 polystyrene, 17 shown as the unfilled circle in Figure 1. T g is found to increase approximately linearly with increasing pressure in the pressure range studied (up to 220 MPa) with dT g /dP equal to 0.30 K/MPa.…”

Section: Resultssupporting

confidence: 89%

“…This same Dylene 8 polystyrene has been used in a handful of studies in our laboratory, in the laboratory of Prof. D. J. Plazek, and in collaborative studies. [16][17][18][19][20] A custom-built piston-type pressurizable dilatometer was used for measurements reported in this study. In this instrument, the polystyrene sample is surrounded by $ 5 g of fluorinated synthetic oil (Krytox 1 GPL107 from DuPont TM ) as confining fluid.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Pressure relaxation of polystyrene and its comparison to the shear response

Meng

Simon

2007

J Polym Sci B Polym Phys

Self Cite

View full text Add to dashboard Cite

Isothermal pressure relaxation as a function of temperature in two pressure ranges has been measured for polystyrene using a self-built pressurizable dilatometer. A master curve for pressure relaxation in each pressure regime is obtained based on the time-temperature superposition principle, and time-pressure superposition of the two master curves is found to be applicable when the master curves are referenced to their pressure-dependent T g . The pressure relaxation master curves, the shift factors, and retardation spectra obtained from these curves are compared with those obtained from shear creep compliance measurements for the same material. The shift factors for the bulk and shear responses have the same temperature dependence, and the retardation spectra overlap at short times. Our results suggest that the bulk and shear response have similar molecular origin, but that longtime chain mechanisms available to shear are lost in the bulk response.

show abstract

Section: Resultssupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Pressure relaxation of polystyrene and its comparison to the shear response

Meng

Simon

2007

J Polym Sci B Polym Phys

Self Cite

View full text Add to dashboard Cite

show abstract

“…For the ultraslow heating rate of 0.01 1C min À1 (Figure 2b), T g was determined to be 89.0 ± 0.5 1C, which is slightly lower than T g (90.6 1C) of a bulk PS sample heated at the same rate. 24 The obtained value of w (9.0±0.5 1C) is almost comparable to the w determined at the rate of 0.5 1C min À1 . Figure 3 shows the temperature dependence of the thickness of thinner films prepared with PS of a molecular weight of 8.35Â10 5 g mol À1 .…”

Section: Resultssupporting

confidence: 77%

Broadening, no broadening and narrowing of glass transition of supported polystyrene ultrathin films emerging under ultraslow temperature variations

Yang

Takahashi

2011

Polym J

View full text Add to dashboard Cite

We report X-ray reflectivity measurements of polystyrene thin films supported on Si substrates at various heating and cooling rates. At a heating rate of 0.05 1C min À1 , the width of the glass transition w does not show any noticeable thickness dependence. However, at faster (0.5 1C min À1 ) and slower (0.01 1C min À1 ) heating rates, w shows remarkable thickness dependence: it broadens at a faster rate and narrows at a slower rate with decreasing film thickness. Our results suggest that the heterogeneous character of the dynamics can be transformed into a homogeneous one in a glassy film with thickness comparable to a critical thickness that depends on the rate of temperature variation. Polymer Journal (2011) 43, 390-397; doi:10.1038/pj.2010.145; published online 19 January 2011Keywords: confinement effects; glass transition; polymer thin films; transition breadth; transition broadening; X-ray reflection INTRODUCTIONThe molecular dynamics in liquid, especially close to and below the glass transition temperature T g , are very heterogeneous. 1 From a theoretical viewpoint in which the mean structural relaxation in glassy systems occurs through rearrangements of correlated particles, the spatial particle region surrounded by other subsystems composed of particles with differing mobilities is called a cooperatively rearranging region. 2,3 Because of the dynamic heterogeneity, temporal relaxations depend on the subsystems, and the glass transition generally occurs within a certain temperature range called the width of glass transition w. Polymers confined in a particular size of cooperatively rearranging region can be good candidates for investigating the spatial size of dynamic heterogeneities. A striking result in confined systems is that T g of thin films often exhibits a remarkable thickness dependence. 4,5 This result strongly suggests that interfaces in a confined system have an important role. Many studies have revealed the properties of interfacial regions and have provided extensive evidence that the molecular mobility is much higher in the free surface region than in the bulk region at the same temperature; 6-9 dynamics near the free surface are very fast. On the other hand, the interaction between a polymer and a solid substrate can suppress molecular relaxation in an interfacial region, leading to peculiar slower dynamics in this region. [9][10][11][12][13] Measurements of the relaxation rate using a 20-nm-thick fluorescently labeled layer that has been incorporated into polymer films have revealed that the rate of dynamics depends on the distance from both the free surface and the interface. These dynamics vary continuously, exhibiting bulk-like characteristics toward the interior layer sandwiched between the surface and the interfacial layers. 9

show abstract

“…The limiting fictive temperature approximates the glass transition temperature (T g ), 63 and we refer to T 0 f as the glass transition temperature (T g ) in the text. The temperature of the DSC was calibrated with indium and tin on heating at 10 K/min and the heat flow of the DSC was calibrated with indium.…”

Section: Glass Transition Temperature (T G ) Measurementmentioning

confidence: 99%

Viscoelastic properties and residual stresses in polyhedral oligomeric silsesquioxane‐reinforced epoxy matrices

Hutcheson

McKenna

et al. 2008

J Polym Sci B Polym Phys

Self Cite

View full text Add to dashboard Cite

Fiber-filled thermosetting polymer composites are extensively used in aerospace industries. One disadvantage of these materials is cure induced or thermally induced residual stresses in the matrix, which may result in deteriorated performance and premature failure. This article explores the use of epoxy/multifunctional polyhedral oligomeric silsesquioxane (POSS) nanocomposites as resins with reduced thermal stress coefficients that result in mitigated residual stresses. The effect of POSS loading on the thermal stress coefficient of the epoxy/POSS nanocomposite resins was investigated from below the b-relaxation to the a-relaxation, or glass transition temperature, (i.e., from À100 to 180 C) by measuring the shear modulus and linear thermal expansion coefficient. The thermal stress coefficient of the epoxy/POSS nanocomposites is found to be a strong function of temperature, decreasing rapidly with decreasing temperature through the a-relaxation region, increasing in the vicinity of the b-relaxation, and then decreasing below the temperature associated with the peak in the b-relaxation. With increasing POSS content, the thermal stress coefficient is reduced compared with the neat resin in the vicinity of the a-relaxation; however, the thermal stress coefficient increases with increasing POSS content below the temperature of the b-relaxation peak.

show abstract

The glass transition temperature versus the fictive temperature

Cited by 224 publications

References 43 publications

Pressure relaxation of polystyrene and its comparison to the shear response

Pressure relaxation of polystyrene and its comparison to the shear response

Broadening, no broadening and narrowing of glass transition of supported polystyrene ultrathin films emerging under ultraslow temperature variations

Viscoelastic properties and residual stresses in polyhedral oligomeric silsesquioxane‐reinforced epoxy matrices

Contact Info

Product

Resources

About