نتایج جستجو برای: glass transition temperature

تعداد نتایج: 742402  

Journal: :The journal of physical chemistry. B 2007
C He J S Lian Q Jiang

In this work, the glass transition of water was studied with density functional theory. The transition temperature was determined by measuring the heat capacity Cp of low-density amorphous water during rapid heating. This technique ensures that all measurements were implemented without crystallization occurring, which is difficult to be achieved experimentally. The results showed that the glass...

2002
S. L. WEBB

Ah&act-The tem~ratu~-de~ndent thermal expansivities of melts along the join ano~hite-diopside have been determined on glassy and liquid samples using a combination of calorimetry, dilatometry, and Pt double bob Archimedean densitometry. Supercooled liquid volumes and molar thermal expansivities were determined using scanning calorimetric and dilatometric measurements of properties in the glass ...

1994
Enzo Marinari Giorgio Parisi Felix Ritort

We discuss the behavior of the fully frustrated hypercubic cell in the infinite dimensional mean-field limit. In the Ising case the system undergoes a glass transition, well described by the random orthogonal model. Under the glass temperature aging effects show clearly. In the XY case there is no sign of a phase transition, and the system is always a paramagnet.

2002
S. Sarkar S. Ramakrishnan A. K. Grover G. Balakrishnan D.McK. Paul

A comparative study of vortex phase diagrams in two weakly pinned low Tc superconductors, Ca3Rh4Sn13 (CaRhSn) and Yb3Rh4Sn13 (YbRhSn), is presented. In CaRhSn, we can witness a disorder-driven transition via the phenomenon of second magnetization peak whose field-temperature dependence is analogous to that often discussed in the context of a Bragg glass (BG) to vortex glass (VG) transition.

1997
David B. Hall Ali Dhinojwala John M. Torkelson

Comparisons are made of the translational and rotational diffusion of small-molecule probes in a polymer near its glass transition temperature, Tg . In the rubbery state, 1.1Tg . T . Tg, translational diffusion is much less temperature dependent than rotational reorientation; in a “quenched” glass, translation and rotation have similar temperature dependencies. This is explained to be a consequ...

Journal: :Physical review letters 2006
Michael Lässig Kay Jörg Wiese

We study secondary structures of random RNA molecules by means of a renormalized field theory based on an expansion in the sequence disorder. We show that there is a continuous phase transition from a molten phase at higher temperatures to a low-temperature glass phase. The primary freezing occurs above the critical temperature, with local islands of stable folds forming within the molten phase...

2013
Yonggang Yao Zhimin Sun Yuanchao Ji Yaodong Yang Xiaoli Tan Xiaobing Ren

(1 - x)(Bi1/2Na1/2)TiO3 - xBaTiO3 has been the most studied Pb-free piezoelectric material in the last decade; however, puzzles still remain about its phase transitions, especially around the important morphotropic phase boundary (MPB). By introducing the strain glass transition concept from the ferroelastic field, it was found that the phase transition from tetragonal (T, P4bm) to rhombohedral...

2012
Prerna P. Dhawade Ramanand N. Jagtap

In differential scanning calorimetry (DSC), remnant moisture loss in samples often overlaps and distorts thermal events such as glass transitions. Temperature modulated DSC (TMDSC) is known for separating such overlapping processes. In this study, chitosan was depolymerized by oxidative degradation method. By this method, chitooligomers of different molecular weights were produced. The glass tr...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2002
Wei-Ren Chen Sow-Hsin Chen Francesco Mallamace

We made small-angle neutron scattering (SANS) study of a Pluronic L64 micellar system in aqueous solution at high polymer concentrations (wt %), 35%<c<53%, in a temperature range where a kinetic glass transition has been observed by photon correlation spectroscopy and zero shear viscosity measurements. We analyze SANS intensity distributions assuming that the micelles are spherical and interact...

1999
X. H. Lina W. L. Johnson W M. Keck

Formation of bulk metallic glass in quaternary Ti-Zr-Cu-Ni alloys by relatively slow cooling from the melt is reported. Thick strips of metallic glass were obtained by the method of metal mold casting. The glass forming ability of the quaternary alloys exceeds that of binary or ternary alloys containing the same elements due to the complexity of the system. The best glass forming alloys such as...

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