Pressure and Temperature Dependence of the Dilute Solution Segmental Dynamics of Anthracene-Labeled Polyisoprene

2002 ◽  
Vol 35 (8) ◽  
pp. 3281-3287 ◽  
Author(s):  
B. J. Punchard ◽  
D. B. Adolf
Keyword(s):  
Temperature Dependence ◽  
Dilute Solution ◽  
Segmental Dynamics

Composition and Temperature Dependence of Terminal and Segmental Dynamics in Polyisoprene/Poly(vinylethylene) Blends

2003 ◽  
Vol 36 (16) ◽  
pp. 6142-6151 ◽  
Author(s):  
Jeffrey C. Haley ◽  
Timothy P. Lodge ◽  
Yiyong He ◽  
M. D. Ediger ◽  
Ernst D. von Meerwall ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Segmental Dynamics

Local segmental dynamics of polyisoprene in dilute solution: picosecond holographic grating experiments

1986 ◽  
Vol 19 (10) ◽  
pp. 2533-2538 ◽  
Author(s):  
Patrick D. Hyde ◽  
Dean A. Waldow ◽  
M. D. Ediger ◽  
Toshiaki Kitano ◽  
Koichi Ito
Keyword(s):  
Holographic Grating ◽  
Dilute Solution ◽  
Segmental Dynamics

Viscosity dependence of the local segmental dynamics of anthracene-labeled polyisoprene in dilute solution

1992 ◽  
Vol 25 (2) ◽  
pp. 867-872 ◽  
Author(s):  
David B. Adolf ◽  
M. D. Ediger ◽  
Toshiaki Kitano ◽  
Koichi Ito
Keyword(s):  
Dilute Solution ◽  
Segmental Dynamics ◽  
Viscosity Dependence

scholarly journals Gradient of Segmental Dynamics in Stereoregular Poly(Methyl Methacrylate) Melts Confined between Pristine or Oxidized Graphene Sheets

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 830
Author(s):  
Alireza Foroozani Behbahani ◽  
Vagelis Harmandaris
Keyword(s):  
Graphene Oxide ◽  
Dielectric Loss ◽  
Methyl Methacrylate ◽  
Temperature Dependence ◽  
Superposition Principle ◽  
Polymer Surface ◽  
Relaxation Times ◽  
Pristine Graphene ◽  
Segmental Dynamics ◽  
Poly Methyl Methacrylate

Segmental dynamics in unentangled isotactic, syndiotactic, and atactic poly(methyl methacrylate) (i-, a-, and s-PMMA) melts confined between pristine graphene, reduced graphene oxide, RGO, or graphene oxide, GO, sheets is studied at various temperatures, well above glass transition temperature, via atomistic molecular dynamics simulations. The model RGO and GO sheets have different degrees of oxidization. The segmental dynamics is studied through the analysis of backbone torsional motions. In the vicinity of the model nanosheets (distances less than ≈2 nm), the dynamics slows down; the effect becomes significantly stronger with increasing the concentration of the surface functional groups, and hence increasing polymer/surface specific interactions. Upon decreasing temperature, the ratios of the interfacial segmental relaxation times to the respective bulk relaxation times increase, revealing the stronger temperature dependence of the interfacial segmental dynamics relative to the bulk dynamics. This heterogeneity in temperature dependence leads to the shortcoming of the time-temperature superposition principle for describing the segmental dynamics of the model confined melts. The alteration of the segmental dynamics at different distances, d, from the surfaces is described by a temperature shift, ΔTseg(d) (roughly speaking, shift of a characteristic temperature). Next, to a given nanosheet, i-PMMA has a larger value of ΔTseg than a-PMMA and s-PMMA. This trend correlates with the better interfacial packing and longer trains of i-PMMA chains. The backbone torsional autocorrelation functions are shown in the frequency domain and are qualitatively compared to the experimental dielectric loss spectra for the segmental α-relaxation in polymer nanocomposites. The εT″(f) (analogous of dielectric loss, ε″(f), for torsional motion) curves of the model confined melts are broader (toward lower frequencies) and have lower amplitudes relative to the corresponding bulk curves; however, the peak frequencies of the εT″(f) curves are only slightly affected.

Pressure−Temperature Dependence of Polymer Segmental Dynamics. Comparison between the Adam−Gibbs Approach and Density Scalings

2006 ◽  
Vol 39 (11) ◽  
pp. 3931-3938 ◽  
Author(s):  
Gustavo A. Schwartz ◽  
Juan Colmenero ◽  
Ángel Alegría
Keyword(s):  
Temperature Dependence ◽  
Segmental Dynamics
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