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Stabilization quenching

J.P. Guillory and C.F. Cook, Energy transfer processes involving ultraviolet stabilizers. Quenching of excited states of ketones, J. Amer. Chem. Soc. 1973, 95, 4885-4891. [Pg.673]

Hydroxybenzophenones represent the largest and most versatile class of ulbaviolet stabilizers that are used to protect materials from the degradative effects of ulbaviolet radiation. They function by absorbing ultraviolet radiation and by quenching elecbonically excited states. [Pg.1011]

Carbon content is usually about 0.15% but may be higher in bolting steels and hot-work die steels. Molybdenum content is usually between 0.5 and 1.5% it increases creep—mpture strength and prevents temper embrittlement at the higher chromium contents. In the modified steels, siUcon is added to improve oxidation resistance, titanium and vanadium to stabilize the carbides to higher temperatures, and nickel to reduce notch sensitivity. Most of the chromium—molybdenum steels are used in the aimealed or in the normalized and tempered condition some of the modified grades have better properties in the quench and tempered condition. [Pg.117]

Tables 1 and 2, respectively, Hst the properties of manganese and its aHotropic forms. The a- and P-forms are brittle. The ductile y-form is unstable and quickly reverses to the a-form unless it is kept at low temperature. This form when quenched shows tensile strength 500 MPa (72,500 psi), yield strength 250 MPa (34,800 psi), elongation 40%, hardness 35 Rockwell C (see Hardness). The y-phase may be stabilized usiag small amounts of copper and nickel. Additional compilations of properties and phase diagrams are given ia References 1 and 2. Tables 1 and 2, respectively, Hst the properties of manganese and its aHotropic forms. The a- and P-forms are brittle. The ductile y-form is unstable and quickly reverses to the a-form unless it is kept at low temperature. This form when quenched shows tensile strength 500 MPa (72,500 psi), yield strength 250 MPa (34,800 psi), elongation 40%, hardness 35 Rockwell C (see Hardness). The y-phase may be stabilized usiag small amounts of copper and nickel. Additional compilations of properties and phase diagrams are given ia References 1 and 2.
After the SO converter has stabilized, the 6—7% SO gas stream can be further diluted with dry air, I, to provide the SO reaction gas at a prescribed concentration, ca 4 vol % for LAB sulfonation and ca 2.5% for alcohol ethoxylate sulfation. The molten sulfur is accurately measured and controlled by mass flow meters. The organic feedstock is also accurately controlled by mass flow meters and a variable speed-driven gear pump. The high velocity SO reaction gas and organic feedstock are introduced into the top of the sulfonation reactor,, in cocurrent downward flow where the reaction product and gas are separated in a cyclone separator, K, then pumped to a cooler, L, and circulated back into a quench cooling reservoir at the base of the reactor, unique to Chemithon concentric reactor systems. The gas stream from the cyclone separator, M, is sent to an electrostatic precipitator (ESP), N, which removes entrained acidic organics, and then sent to the packed tower, H, where SO2 and any SO traces are adsorbed in a dilute NaOH solution and finally vented, O. Even a 99% conversion of SO2 to SO contributes ca 500 ppm SO2 to the effluent gas. [Pg.89]

Figure 3-16. Flow diagram of the Lummus process for producing butadiene (1) reactor, (2) quenching, (3) compressor, (4) cryogenic recovery, (5) stabilizer, (6) extraction. Figure 3-16. Flow diagram of the Lummus process for producing butadiene (1) reactor, (2) quenching, (3) compressor, (4) cryogenic recovery, (5) stabilizer, (6) extraction.
Most radicals are transient species. They (e.%. 1-10) decay by self-reaction with rates at or close to the diffusion-controlled limit (Section 1.4). This situation also pertains in conventional radical polymerization. Certain radicals, however, have thermodynamic stability, kinetic stability (persistence) or both that is conferred by appropriate substitution. Some well-known examples of stable radicals are diphenylpicrylhydrazyl (DPPH), nitroxides such as 2,2,6,6-tetramethylpiperidin-A -oxyl (TEMPO), triphenylniethyl radical (13) and galvinoxyl (14). Some examples of carbon-centered radicals which are persistent but which do not have intrinsic thermodynamic stability are shown in Section 1.4.3.2. These radicals (DPPH, TEMPO, 13, 14) are comparatively stable in isolation as solids or in solution and either do not react or react very slowly with compounds usually thought of as substrates for radical reactions. They may, nonetheless, react with less stable radicals at close to diffusion controlled rates. In polymer synthesis these species find use as inhibitors (to stabilize monomers against polymerization or to quench radical reactions - Section 5,3.1) and as reversible termination agents (in living radical polymerization - Section 9.3). [Pg.14]

Inhibitors and retarders are used to stabilize monomers during storage or during processing (e.g, synthesis, distillation). They are often used to quench polymerization when a desired conversion has been achieved. They may also be used to regulate or control the kinetics of a polymerization process. [Pg.264]

Treating petroleum oils with 3-5% calcium alkyl salicylate and 0.5-3% triethanolamine salts of phosphoric acid esters and ethoxylated dodecyl alcohol increases oxidation-thermal stability at 180-200°C in the manufacture of oil for metal parts quenching. The agent provides also short-term anticorrosion protection of the hardened articles [261]. Phosphoric acid salt alkyl esters are used in anticorrosives and aqueous dispersions in waterborne polyester coatings for metals [244]. [Pg.608]

To avoid this phase change, zirconia is stabilized in the cubic phase by the addition of a small amount of a divalent or trivalent oxide of cubic symmetry, such as MgO, CaO, or Y2O3. The additive oxide cation enters the crystal lattice and increases the ionic character of the metal-oxygen bonds. The cubic phase is not thermodynamically stable below approximately 1400°C for MgO additions, 1140°C for CaO additions, and below 750°C for Y2O3 additions. However, the diffusion rates for the cations are so low at Xhtstsubsolidus temperatures that the cubic phase can easily be quenched and retained as a metastable phase. Zirconia is commercially applied by thermal spray. It is also readily produced by CVD, mostly on an experimental basis. Its characteristics and properties are summarized in Table 11.8. [Pg.311]

Requirements of Standards. The general requirements for luminescence standards have been discussed extensively (3,7-9) and include stability, purity, no overlap between excitation and emission spectra, no oxygen quenching, and a high, constant qtiantum yield independent of excitation wavelength. Specific system parameters--such as the broad or narrow excitation and emission spectra, isotropic or anisotropic emission, solubility in a specific solvent, stability (standard relative to sample), and concentration--almost require the standard to be in the same chemical and physical environment as the sample. [Pg.99]

Based on the flame-hole dynamics [59], dynamic evolutions of flame holes were simulated to yield the statistical chance to determine the reacting or quenched flame surface under the randomly fluctuating 2D strain-rate field. The flame-hole d5mamics have also been applied to turbulent flame stabilization by considering the realistic turbulence effects by introducing fluctuating 2D strain-rate field [22] and adopting the level-set method [60]. [Pg.63]


See other pages where Stabilization quenching is mentioned: [Pg.317]    [Pg.126]    [Pg.283]    [Pg.588]    [Pg.317]    [Pg.126]    [Pg.283]    [Pg.588]    [Pg.2902]    [Pg.87]    [Pg.315]    [Pg.388]    [Pg.392]    [Pg.274]    [Pg.149]    [Pg.419]    [Pg.451]    [Pg.10]    [Pg.397]    [Pg.89]    [Pg.481]    [Pg.440]    [Pg.2418]    [Pg.370]    [Pg.13]    [Pg.83]    [Pg.44]    [Pg.399]    [Pg.400]    [Pg.404]    [Pg.435]    [Pg.878]    [Pg.328]    [Pg.441]    [Pg.1033]    [Pg.1038]    [Pg.127]    [Pg.1010]    [Pg.631]    [Pg.167]    [Pg.56]   
See also in sourсe #XX -- [ Pg.384 ]




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