Glass viscous properties

In the Irvine-Park falling needle viscometer (FNV) (194), the moving body is a needle. A small-diameter glass or stainless steel needle falls vertically in a fluid. The viscous properties and density of the fluid are derived from the velocity of the needle. The technique is simple and useflil for measuring low (down to lO " ) shear viscosities. The FNV-100 is a manual instmment designed for the measurement of transparent Newtonian and non-Newtonian... 

Using a special hot-press procedure, Schweiger et al. (1998) and Frank et al. (1998) also developed a powder-processed lithium disilicate glass-ceramic. To optimize the viscous properties for the hot-press procedure at approximately 920°C, components such as La2 3 hlgO, and pigments were added to the main components Si02, ZnO. The fabrication... 

The shear modulation SPM was introduced as a new technique to measure the glass transition temperature. We have shown that this mode is sensitive to the viscous properties of the films. At Tg, the tip sinks into the sample and a hole begins to form. This sinking process causes the response anq)litude to increase. For thick films of PS, i.e. thicknesses about 200 nm, we have verified that the glass transition at the air-polymer interface is bulk-like within an uncertainty of 2 K. 

Most materials, such as polymers, metals and glasses, possess some elastic and some viscous properties, and are described as viscoelastic. This causes the... 

Glazing uses the viscous properties of glass to form a smooth continuous layer on a ceramic substrate. Pots were the first to be glazed. 

Glass transition Transition region or state in which an amorphous polymer changed from (or to) a viscous or rubbery condition to (or from) a hard and relatively brittle one. Transition occurs over a narrow temperature region similar to solidification of a liquid to a glassy state. This transformation causes hardness, brittleness, thermal expansibility, specific heat, and other properties to change dramatically. 

The all-important difference between the friction properties of elastomers and hard solids is its strong dependence on temperature and speed, demonstrating that these materials are not only elastic, but also have a strong viscous component. Both these aspects are important to achieve a high friction capability. The most obvious effect is that temperature and speed are related through the so-called WLF transformation. For simple systems with a well-defined glass transition temperature the transform is obeyed very accurately. Even for complex polymer blends the transform dominates the behavior deviations are quite small. 

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