Self-extinction

The burning rate characteristics of AP composite propellants with and without LiF are shown in Fig. 7-13. Though the burning rate without LiF increases as pressure increases, with LiF the burning rate decreases as the concentration of LiF increases at constant pressure. Further increase of the LiF concentration at a given pressure eventually results in self-extinction of the propellant1151. Thus, one can state that LiF not only decreases the burning rate but also inhibits steady-state combustion at or below a certain pressure. 

Water-soluble silicate, containing an organic alkaline cation, can be obtained by interaction of quaternary organic ammonium base salts and amorphous silica. The relationship of Si02 to the organic base is 1.65 1 for DBUS and 2.0 1 for DBNS. It should be noted that the soluble organic alkali silicates, for example, tetrabutylam-monium silicate (TBAS) is also used as a component of self-extinction binder. 

Resistant to temperatures and chemical agents, including water, overheated vapor, solutions of alkali, mineral acids and salts, microorganisms and radiation. Decomposes in aliphatic hydrocarbons, has high mechanical and dielectric strength, stiffness, dimensional stability, resistance to sparking, self-extinction when removed from fire. 

This result may be explained by the model, in which the degree of heat dissipation is a key factor determining the self-extinction. Hence, we introduce a term corresponding to the degree of heat dissipation thermal diffusivity a. The equation HRR is modified as follows ... 

The study of the ignition time, the time of self-extinction, and the weight losses at burning has shown that the synthesized phosphorus-containing poly-urethane-semicarbazides are among the conventional fire-proof or self-extinguishing materials. 

Many of the physical properties are not affected by the optical composition, with the important exception of the melting poiat of the crystalline acid, which is estimated to be 52.7—52.8°C for either optically pure isomer, whereas the reported melting poiat of the racemic mixture ranges from 17 to 33°C (6). The boiling poiat of anhydrous lactic acid has been reported by several authors it was primarily obtained duriag fractionation of lactic acid from its self-esterification product, the dimer lactoyUactic acid [26811-96-1]. The difference between the boiling poiats of racemic and optically active isomers of lactic acid is probably very small (6). The uv spectra of lactic acid and dilactide [95-96-5] which is the cycHc anhydride from two lactic acid molecules, as expected show no chromophores at wavelengths above 250 nm, and lactic acid and dilactide have extinction coefficients of 28 and 111 at 215 nm and 225 nm, respectively (9,10). The iafrared spectra of lactic acid and its derivatives have been extensively studied and a summary is available (6). 

The kinetics of reactions involving the tributylstannyl radical have been refined by laser flash time-resolved UV spectroscopy. The measured extinction coefficient of the BujSn- radical in benzene was 1620 40 M 1cm 1 at 400 nm, the rate constant of the reaction of the /-butoxyl radical with Bu3SnH was (3.5 0.3) x 108M 1 s 1, and the rate constant for the self-reaction of the Bu3Sn radical was (3.6 0.3) x 109 M s1. S29... 

Neisewander JL, O Dell LE, Tran-Nguyen LT, Castaneda E, Fuchs RA. 1996. Dopamine overflow in the nucleus accumbens during extinction and reinstatement of cocaine self-administration behavior. Neuropsychopharmacology 15(5) 506-514. 

O Dell LE, Koob GF (2007) Nicotine deprivation effect in rats with intermittent 23-hour access to intravenous nicotine self-administration. Pharmacol Biochem Behav 86 346-353 O Dell LE, Chen SA, Smith RT, Specie SE, Balster RL, Paterson NE, Markou A, Zorrilla EP, Koob GF (2007) Extended access to nicotine self-administration leads to dependence Circadian measures, withdrawal measures, and extinction behavior in rats. J Pharmacol Exp Ther 320 180-193... 

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