We report the first measurements of the glass transition temperature Tg for thin freely standing polystyrene (PS) films. We have used Brillouin light scattering to measure Tg for freely standing films of different thicknesses. We find that Tg decreases linearly with film thickness h for h # 700 Å, with a reduction of 70 K for a film with h ­ 290 Å. These measurements characterize unambiguously ...

Be diffusivity data in the bulk metallic glass forming alloy Zr46.7Ti8.3Cu7.5Ni10Be27.5 are reported for temperatures between 530 and 710 K, extending 85 K into the supercooled liquid state of the alloy. At the glass transition temperature Tg, a change in temperature dependence of the data is observed, and above Tg the diffusivity increases more quickly with temperature than below. The data in ...

The aim of the present work was to study the shrinkage phenomenon during convective drying of papaya cubes and relate its extension with glass transition. A convective tray dryer was used for the experiments, which were carried out at air temperatures of 40 and 70°C and air velocity of 1.0m/s. The shrinkage behaviour was accomplished by total area and apparent volume alterations along drying. S...

Protective mechanisms of casein-based microcapsules containing mannitol on Lactobacillus acidophilus and Lactococcus lactis ssp. cremoris, changes in their secondary protein structures, and glass transition of the microcapsules were studied after sprayor freeze-drying and after 10 wk of storage in aluminum foil pouches containing different desiccants (NaOH, LiCl, or silica gel) at 25°C. An in s...

Optical fibers are drawn with resin coatings that protect the glass. In general UV-curable resins are used for the coatings, and in most single-mode (SM) fibers a dualcoating structure is adopted. Each coating layer has an independent function in the protection of the glass. The coating in direct contact with the glass is known as the primary (P) coating, with the role of acting as a buffer aga...

The specific heat capacity (Cp) of amorphous sucrose was determined by DSC after annealing at a particular temperature within the glass transition (Tg) region. The enthalpy recovery after physical aging was obtained from the Cp data through the Tg region after several aging times. This data was fitted to the empirical Williams-Watts equation to obtain values for the mean molecular relaxation ti...

We report the synthesis and characterization of an analogous series of small organic molecules derived from a well-known glass former, 1,3-bis(1-naphthyl)-5-(2-naphthyl)benzene (α,α,β-TNB). Synthesized molecules include α,α,β-TNB, 3,5-di(naphthalen-1-yl)-1-phenylbenzene (α,α-P), 9-(3,5-di(naphthalen-1-yl)phenyl)anthracene (α,α-A), 9,9'-(5-(naphthalen-2-yl)-1,3-phenylene)dianthracene (β-AA) and ...

One of the most characteristic features of glass-forming liquids is the sharp slowing down of relaxation times, τ, upon cooling. In these materials relaxation dynamics exhibit a non-Arrhenius temperature dependence usually described by Vogel-Fulcher-Tamman (VFT) relation [1]. However, for majority of glassforming liquids it is impossible to fit data in the entire temperature range with a single...

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...