New Glass Forming Systems

Angell, C. Austen; Elias, A. M.

doi:10.1007/978-94-009-5107-5_69

Cited by 2 publications

(2 citation statements)

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“…Figure (bottom) shows the fragility plot of the copolymers together with some literature PMMA homopolymers. In this representation for the viscosity, the fragility index m characterizes the steepness of the slope of logη dependence on T g / T near T g : m = d(log η( T ))/d( T g / T )| T g . A stronger deviation from Arrhenius behavior corresponds to a more fragile system and to a larger m value.…”

Section: Resultsmentioning

confidence: 99%

Heterogeneity and Dynamics in Azobenzene Methacrylate Random and Block Copolymers: A Nanometer–Nanosecond Study by Electron Spin Resonance Spectroscopy

et al. 2015

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The effects of the different architecture on the dynamic response at nanometers and nanoseconds was investigated by means of electron spin resonance spectroscopy in a series of random and block copolymers of an azobenzene methacrylate (MA4) and methyl methacrylate (MMA) counits. The study evidenced the presence of fast and slow molecular sites for the molecular reorientation at nanoscale, modulated by the amount of MA4 counits in the random copolymers, and by the self-assembly in supramolecular structures in the block copolymers. A series of dynamics features was found, such as the presence of memory effects, the existence and the degree of coupling of the rotational dynamics to the structural relaxation of the matrix or to its viscosity, and the population of the different dynamic sites, that provided a detailed description and characterization of the different mechanisms leading the dynamic response of the structurally different copolymer systems.

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Section: Resultsmentioning

confidence: 99%

Heterogeneity and Dynamics in Azobenzene Methacrylate Random and Block Copolymers: A Nanometer–Nanosecond Study by Electron Spin Resonance Spectroscopy

et al. 2015

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“…To explain why some materials form glasses and some do not is a challenging question. A variety of semi-empirical criteria for glass formation (Rawson 1967, Wong and Angel1 1976, Hafner 1981, Cahn 1983, Somner 1985 in terms of physical, chemical and crystallographic properties have been proposed, demonstrating that a large number of factors are involved. Since glass formation is solidification without crystallisation, the ability of a material to form a glass must strongly depend on the time available for crystallisation during cooling, which is determined by the cooling rate.…”

Section: Introductionmentioning

confidence: 99%

Models of the glass transition

1986

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The different physical aspects of glass transitions are reviewed and models aiming at their explanation are described. The following three main aspects are distinguished:(i) the degree of stability of supercooled liquids with respect to crystallisation, (ii) the variation of physical properties of supercooled liquids in metastable equi-(iii) the arrest of structural relaxation at the glass transition.The physical significance of computer simulations of glass transitions in simple liquids and the question of a hidden phase transition underlying an observed glass transition are examined critically. In relation to the stability problem, the geometrical constraints operative in typical disordered structures, such as random sphere packings and random covalent networks, are also discussed. A general survey of glass transition phenomena and concepts is presented in an introductory section. librium above the glass transition, and

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New Glass Forming Systems

Cited by 2 publications

References 0 publications

Heterogeneity and Dynamics in Azobenzene Methacrylate Random and Block Copolymers: A Nanometer–Nanosecond Study by Electron Spin Resonance Spectroscopy

Heterogeneity and Dynamics in Azobenzene Methacrylate Random and Block Copolymers: A Nanometer–Nanosecond Study by Electron Spin Resonance Spectroscopy

Models of the glass transition

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