نتایج جستجو برای: glass transition temperature

تعداد نتایج: 742402  

Journal: :The journal of physical chemistry. B 2007
D Costa R Ruberto F Sciortino M C Abramo C Caccamo

We report a study of the mode-coupling theory (MCT) glass transition line for the Girifalco model of C60 fullerene. The equilibrium static structure factor of the model, the only required input for the MCT calculations, is provided by molecular dynamics simulations. The glass transition line develops inside the metastable liquid-solid coexistence region and extends down in temperature, terminat...

In particular, chalcogenide glasses and glass-ceramics are new materials that exhibit good transparency in infrared region (0.8-12µm). We can overcome the main weakness of these glasses by improving the hardness through controlling crystallization. In this paper, we report results of a study on chalcogenide glasses in the ternary system of As-Se-Ge with nominal composition of Snx (Se...

2016
U. Sailaja M. Shahin Thayyil N.S. Krishna Kumar G. Govindaraj

Fenofibrate is mainly used to reduce cholesterol level in patients at risk of cardiovascular disease. Thermal transition study with the help of differential scanning calorimetry (DSC) shows that the aforesaid active pharmaceutical ingredient (API) is a good glass former. Based on our DSC study, the molecular dynamics of this API has been carried out by broadband dielectric spectroscopy (BDS) co...

Journal: :The Journal of chemical physics 2015
Men Zhu Jun-Qiang Wang John H Perepezko Lian Yu

We report that the common polyalcohol D-mannitol may have two amorphous phases related by a first-order transition. Slightly above its glass transition temperature Tg (284 K), the supercooled liquid (SCL) of D-mannitol transforms to a low-energy, apparently amorphous phase with stronger hydrogen bonds. The enthalpy of this so-called Phase X is approximately halfway between those of the known am...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2015
Misaki Ozawa Walter Kob Atsushi Ikeda Kunimasa Miyazaki

We use computer simulations to study the thermodynamic properties of a glass-former in which a fraction c of the particles has been permanently frozen. By thermodynamic integration, we determine the Kauzmann, or ideal glass transition, temperature [Formula: see text] at which the configurational entropy vanishes. This is done without resorting to any kind of extrapolation, i.e., [Formula: see t...

Aiyoub Parchehbaf Jadid Mohammad Hossein Nasirtabrizi, Zeinab Mohammadpoor Ziaei

Maleic anhydride (MAN) copolymers with methyl methacrylate(MMA), ethyl methacrylate(EMA), methyl acrylate(MA), ethyl acrylate (EA) and buthyl acrylate (BA) ( in a 1:1 mole ratio) were synthesized by free radical polymerizations method under vacuum -azobis(isobutironitrile)(AIBN) as an initiator of reaction at 701C. The copolymer compositions were determined using related 1H NMR spectra techni...

2016
Kenneth F. Kelton

Abstract: Fragility is a concept that is often correlated with glass formability. It is generally defined in terms of dynamical aspects of the liquid, usually based on the rate of increase of the viscosity as a function of the inverse temperature scaled to the glass transition temperature, Tg (i.e. Tg/T). Our experimental studies of the temperature dependence of the liquid structure factor, S(q...

2011
Lokesh Kumar Dharmesh Popat Arvind K. Bansal

This manuscript studied the effect of counterion on the glass transition and recrystallization behavior of amorphous salts of prazosin. Three amorphous salts of prazosin, namely, prazosin hydrochloride, prazosin mesylate and prazosin tosylate were prepared by spray drying, and characterized by optical-polarized microscopy, differential scanning calorimetry and powder X-ray diffraction. Modulate...

2015
Kajetan Koperwas Andrzej Grzybowski Satya N. Tripathy Elzbieta Masiewicz Marian Paluch

In this paper, we consider the glass transition as a kinetic process and establish one universal equation for the pressure coefficient of the glass transition temperature, dTg/dp, which is a thermodynamic characteristic of this process. Our findings challenge the common previous expectations concerning key characteristics of the transformation from the liquid to the glassy state, because it sug...

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