Mechanical hole-burning spectroscopy: Demonstration of hole burning in the terminal relaxation regime

Shi, Xiasheng; McKenna, Gregory B.

doi:10.1103/physrevb.73.014203

Cited by 15 publications

(9 citation statements)

References 49 publications

(89 reference statements)

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“…The reasons that the stress relaxation‐based predictions are so high are unclear and deviations could be nonuniversal. For example, Shi and McKenna [ 82 ] found reasonable agreement for a low density polyethylene using the stress relaxation approach, with deviations being such that the data were above the predictions, different from the Giacomin et al [ 111 ] data of Figure 23. Differences of this sort suggest that the FTR type of analysis predicting certain trends, for example, in

I_{3} / I_{1}

versus

γ^{2}

due to the form of the constitutive model, are of interest, but the issue of finding quantitative agreement with the LAOS data itself as well as data from other deformation histories can be problematic.…”

Section: Dynamic Heterogeneity and Nonlinear Viscoelasticity In Polymersmentioning

confidence: 97%

“…The pulse‐probe sequences used are shown in Figures 16A,B shows how the vertical and horizontal holes are determined. [ 81–83 ] The relevant equations describing the response are:

G_{pos} ((),, γ, t) goodbreak= G_{pump} ((),, γ, t) goodbreak+ G {(γ, t)}_{\mod}

G_{neg} ((),, γ, t) goodbreak= G_{pump} ((),, γ, t) goodbreak- G {(γ, t)}_{\mod}

G_{\mod} ((),, γ, t) goodbreak= \frac{G_{pos} ((),, γ, t) - G_{neg} ((),, γ, t)}{2}

where

G_{pos} ((),, γ, t) and G_{neg} ((),, γ, t)

are the measured relaxation responses in the positive and negative directions after the large pump sinewave,

G_{pump} ((),, γ, t)

is the after effect of the applied sinewave, and

G_{\mod} ((),, γ, t)

is the modified response of interest and that is compared to the linear response of the system without application of the large amplitude pump. Then,

∆ G ((), t) = G_{linear} ((), t) - G_{\mod} ((), t)

represents the vertical hole.…”

Section: Dynamic Heterogeneity and Nonlinear Viscoelasticity In Polymersmentioning

confidence: 99%

“…The hole burning did not seem to correlate with distance between entanglements, the number of entanglements per chain (entanglement density) or with the chain end density. On the other hand, in branched polyethylene, Shi and McKenna [ 81,82 ] did observe holes in the terminal flow regime. A point of importance in all hole burning experiments is that, as noted above, the magnitude of the holes is very small relative to the overall linear or modified response.…”

Section: Dynamic Heterogeneity and Nonlinear Viscoelasticity In Polymersmentioning

confidence: 99%

“…The original ideas of the pump-probe methodology considered that using the positive and negative probes would eliminate the nonlinear "after effect" that might occur even if the material dynamics were homogeneous. Because polymers have relatively weak dielectric responses, Shi and McKenna [81,82] found that mechanical spectral hole burning offered a potential to examine the dynamics of polymeric systems, in their case polymer melts and solutions. The approach is similar to the dielectric except that the pulse and probe are in the mechanical domain; in the Shi and McKenna case, the stimulus was strain and the response was stress.…”

Section: Nonresonant Spectral Hole Burningmentioning

confidence: 99%

“…The pulse-probe sequences used are shown in Figures 16A,B shows how the vertical and horizontal holes are determined. [81][82][83] The relevant equations describing the response are:…”

Section: Nonresonant Spectral Hole Burningmentioning

confidence: 99%

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Some open challenges in polymer physics*

McKenna

Chen

Mangalara

et al. 2022

Polymer Engineering & Sci

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Three subjects in polymer and soft matter physics are outlined in the present article. The first relates to concepts of an ideal glass transition. We describe work on ultra-stable glass, either a 20-million-year-old amber or a vapor deposited amorphous fluoropolymer, which examines the temperature dependence of the dynamics in a window between a low fictive temperature and the glass transition temperature. From this "finesse" of the problem of the geological time scales in sub-glass temperature systems strong evidence that the divergence of the relaxation times at finite temperature from WLF-types of extrapolation is not correct. The second topic is polymer nonlinear viscoelasticity as it relates to dynamic heterogeneity. We show results from mechanical hole burning experiments that suggest that dynamic heterogeneity arises from the nature of specific relaxation mechanisms rather than heterogeneous changes in, for example, the fictive temperature. Included is a discussion of large amplitude oscillatory shear testing and how it relates to characterization of nonlinear viscoelastic materials. The last topic addressed is the rheology of circular macromolecules. Here, we take a historical perspective and describe important new results from several laboratories that seem inconsistent. New works from our own studies on circular DNA are also discussed.

show abstract

I_{3} / I_{1}

versus

γ^{2}

Section: Dynamic Heterogeneity and Nonlinear Viscoelasticity In Polymersmentioning

confidence: 97%

“…The pulse‐probe sequences used are shown in Figures 16A,B shows how the vertical and horizontal holes are determined. [ 81–83 ] The relevant equations describing the response are:

G_{pos} ((),, γ, t) goodbreak= G_{pump} ((),, γ, t) goodbreak+ G {(γ, t)}_{\mod}

G_{neg} ((),, γ, t) goodbreak= G_{pump} ((),, γ, t) goodbreak- G {(γ, t)}_{\mod}

G_{\mod} ((),, γ, t) goodbreak= \frac{G_{pos} ((),, γ, t) - G_{neg} ((),, γ, t)}{2}

where

G_{pos} ((),, γ, t) and G_{neg} ((),, γ, t)

are the measured relaxation responses in the positive and negative directions after the large pump sinewave,

G_{pump} ((),, γ, t)

is the after effect of the applied sinewave, and

G_{\mod} ((),, γ, t)

is the modified response of interest and that is compared to the linear response of the system without application of the large amplitude pump. Then,

∆ G ((), t) = G_{linear} ((), t) - G_{\mod} ((), t)

represents the vertical hole.…”

Section: Dynamic Heterogeneity and Nonlinear Viscoelasticity In Polymersmentioning

confidence: 99%

Section: Dynamic Heterogeneity and Nonlinear Viscoelasticity In Polymersmentioning

confidence: 99%

Section: Nonresonant Spectral Hole Burningmentioning

confidence: 99%

“…The pulse-probe sequences used are shown in Figures 16A,B shows how the vertical and horizontal holes are determined. [81][82][83] The relevant equations describing the response are:…”

Section: Nonresonant Spectral Hole Burningmentioning

confidence: 99%

See 3 more Smart Citations

Some open challenges in polymer physics*

McKenna

Chen

Mangalara

et al. 2022

Polymer Engineering & Sci

Self Cite

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show abstract

Multidimensional Incoherent Time‐Resolved Spectroscopy and Complex Kinetics

Berg

2012

Advances in Chemical Physics

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Mechanical hole burning spectroscopy in an SIS tri‐block copolymer

Qin

Shi

McKenna

2007

J Polym Sci B Polym Phys

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We have previously developed a mechanical hole burning spectroscopy (MSHB) technique that promises to be a powerful tool for the investigation of dynamic heterogeneity of polymeric materials. This is because, unlike its dielectric analogue, MSHB can be used to characterize materials having a weak dielectric response, a particular feature of polymeric materials. However, while both mechanical and dielectric hole burning show behaviors that are consistent with dynamic heterogeneity in the materials, it is still unclear what the relationship between the hole properties, for example, frequency and amplitude, and the actual nature of the heterogeneity and particularly the length scale being probed. Here, we provide first evidence that a known length scale can be probed by the MSHB method by using a tri‐block copolymer as a “calibration” sample. The heterogeneity of a styrene‐isoprene‐styrene copolymer was investigated in the vicinity of the order‐disorder transition temperature (ODT). It was found that the amplitudes of the mechanical holes gradually decrease as the order‐disorder transition is traversed from the region with ordered structures. In the disordered state of the block copolymer, no apparent mechanical holes were detected. In contrast, mechanical holes were burned in the heterogeneous region and the hole amplitude increased as the depth into the ordered structure increased. Hence, the MSHB technique provides a qualitative correlation between the amplitude of the burned holes and the corresponding heterogeneity. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3277–3284, 2007

show abstract

Mechanical hole-burning spectroscopy: Demonstration of hole burning in the terminal relaxation regime

Cited by 15 publications

References 49 publications

Some open challenges in polymer physics*

Some open challenges in polymer physics*

Multidimensional Incoherent Time‐Resolved Spectroscopy and Complex Kinetics

Mechanical hole burning spectroscopy in an SIS tri‐block copolymer

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