Although it has long been recognized that dynamics in supercooled liquids might be spatially heterogeneous, only in the past few years has clear evidence emerged to support this view. As a liquid is cooled far below its melting point, dynamics in some regions of the sample can be orders of magnitude faster than dynamics in other regions only a few nanometers away. In this review, the experimental work that characterizes this heterogeneity is described. In particular, the following questions are addressed: How large are the heterogeneities? How long do they last? How much do dynamics vary between the fastest and slowest regions? Why do these heterogeneities arise? The answers to these questions influence practical applications of glass-forming materials, including polymers, metallic glasses, and pharmaceuticals.

Spatially Heterogeneous Dynamics in Supercooled Liquids

Biopolymer-based hydrogels as scaffolds for tissue engineering applications: a review

A review of nonlinear oscillatory shear tests: Analysis and application of large amplitude oscillatory shear (LAOS)

Poly(ionic liquid)s: An update

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The Merck Index

Birefringence of amorphous polymers. 1. Dynamic measurement on polystyrene

For highly entangled cis-polyisoprene (PI) star polymers having more than 10 entanglements in each arm, dielectric and viscoelastic properties were examined within a context of the generalized tube...

Dielectric and Viscoelastic Relaxation of Highly Entangled Star Polyisoprene: Quantitative Test of Tube Dilation Model

Overshoot of shear stress, σ, and the first normal stress difference, N1, in shear flow were investigated for polystyrene solutions. The magnitudes of shear corresponding to these stresses, γσm and γNm, for entangled as well as nonentangled solutions were universal functions of γ˙τeq, respectively, and γNm was approximately equal to 2γσm at any rate of shear, γ˙. Here τeq = τR for nonentangled systems and τeq = 2τR for entangled systems, where τR is the longest Rouse relaxation time evaluated from the dynamic viscoelasticity at high frequencies. Only concentrated solutions exhibited stress overshoot at low reduced rates of shear, γ˙τeq 1, γσm and γNm were approximately proportional to γ˙τeq. At very high rates of shear, the peak of σ is located at t = τR, possibly indicating that the polymer chain shrinks with a characteristic time τR in dilute solutions. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1917–1925, 2000

Stress overshoot of polymer solutions at high rates of shear

Young's modulus of amorphous polymers around the glass-to-rubber transition zone can be separated into two component functions (R and G) through a modified stress-optical rule (Inoue et al. Macromo...

Role of Polymer Chain Flexibility on the Viscoelasticity of Amorphous Polymers around the Glass Transition Zone

The molecular picture of dynamic tube dilation (DTD) was tested for viscoelastic and dielectric data for two series of entangled binary blends of linear cis-polyisoprenes (PI) having 10-3M2 = 308 and 10-3M1 = 94.0 or 21.4. The volume fraction υ2 of the high-M chains was varied from 0.005 to 0.5. The Struglinski−Graessley parameter rSG (= M2Me2M1-3), specifying the constraint release (CR) contribution to the relaxation of high-M chains at small υ2, was quite different for the two series of blends (rSG = 0.0093 and 0.79). For large υ2 (= 0.5), the full-DTD picture treating the relaxed portions of the chains as a simple solvent held satisfactorily in the entire range of time t irrespective of the rSG value. However, on a decrease of υ2, this picture began to fail at intermediate t and further at long t (in the terminal regime of the high-M chains), and the failure was more significant for the blend with small rSG. This failure occurred when the number βCR(t) of the entanglement segments equilibrated through ...

Tadashi Inoue

Papers

Birefringence of amorphous polymers. 1. Dynamic measurement on polystyrene

Dielectric and Viscoelastic Relaxation of Highly Entangled Star Polyisoprene: Quantitative Test of Tube Dilation Model

Stress overshoot of polymer solutions at high rates of shear

Role of Polymer Chain Flexibility on the Viscoelasticity of Amorphous Polymers around the Glass Transition Zone

Test of Full and Partial Tube Dilation Pictures in Entangled Blends of Linear Polyisoprenes