The Decay of Glass

a supercooled liquid, is in a metastable state, that is, an apparently stable condition that may be perturbed by external conditions and undergo unpredictable changes, so that the supercooled liquid may be converted to a solid. When glass is made from a well-balanced mixture of former, modifier, and stabilizer, it is remarkably stable. Environmental changes may. 

FIGURE 28 Oxygen isotopes in ancient glass. Oxygen, which consists mainly of a 

Various stages in the decay of glass have been defined dulling, which enfails the loss of clarity and transparency, is the simplest the for- 

FIGURE 29 Crusts of weathered glass. The deterioration of glass and the formation 

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Fig. 19. Experimental spin alignment decay curves of chain deuterated PS-d3 at temperatures above and below the glass transition for various evolution times t,. Note the different timescales of t2 at the different temperatures. The straight lines indicate the decays of the plateau values on the timescale of the spin-lattice relaxation time T,. Sample characterization Mw = 141000, Mw/Mn = 1.13, atactic...

Glass and fused quartz form one of the most inert surfaces with respect to heterogeneous de-excitation of 02( A ). The coefficient of heterogeneous decay of yin this event lies within lO - 10, depending upon the experiment conditions. As the temperature of glass walls increases, the y decrease by the law... 

Radon s main use is as a short-lived source of radioactivity for medical purposes. It is collected from the decay of radium as a gas and sealed in small glass capsules that are then inserted at the site of the cancer. It is also used to trace leaks in gas and liquid pipelines and to measure their rate of flow. The rate at which radon gas escapes from the Earth is one measurement that helps scientists predict earthquakes. 

In contrast, the curve E2 (isotactic polypropylene) is characteristic for partially crystalline polymers. The modulus is three decades higher than in an elastomer. At the glass transition temperature [T (2) 0 °C] the decay of the E modulus is small it does not drop to the lower level of the molten state before the melting point. 

Figure 15. Amplitude -time plots obtained from AFM measurements for the decay of sinusoidal 1-D gratings with the periods indieated on the surface of a silicate glass(Corning 1737) annealed in air at827C.[42], The exponential decay constant scales approximately as q as expected for a viscous flow controlled process[l].

FIGURE 10.30 Percent conversion-time profiles for the decay of 5 PAHs in diesel exhaust particulate matter (Dp = 0.5 p.m) collected on glass fiber filters and exposed to 1.5 ppm of ozone in air under Hi-Vol sampling conditions. Half-lives (dotted line) decrease in order of the Nielsen (1984) electrophilic reactivity scale (Table 10.30) BaP, benzo[u]pyrene BghiP, benzo[ghi]pclyIcne BeP, benzolelpyrene IndP, indeno[l,2,3-cd]pyrene BkFI, benzolk]fluoranthene (adapted from Van Vaeck and Van Cauwenberghe, 1984). 

TABLE 9.10. Pseudo-First-Order Rate Constants and Arrhenius Parameters for the Decay of Triplet Ph2C (14a) in Organic Glasses... 

Fig. 2. The decay of the intensity of the sharp ESR line of the trapped electrons in pure 3-methylpentane glass irradiated by y-rays to a dose of 3 X 106 rad at 77° K. o, Observed values , remainders after subtraction of the values corresponding to the straight line A from the observed values. Line A represents the slowly disappearing electrons and line B represents the fast disappearing electrons...

Fig. 24. Kinetic curves for the decay of e at different temperatures in a water-ethylene glycol glass (30 70) containing 0.384M of HC1. The data are from ref. 79.

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