Double Heating Method

The double heating method is suggested as an improvement of the continuous method. By the continuous method, the determined value for rubber is lower and that for carbon black is higher than the real values. Using the double heating method, it becomes possible to distinguish between mass losses due to oxidation of the polymeric residue after the first stage decomposition and those due to oxidation of the carbon black. 

Heat the sample from ambient temperature to 550 °C in an N 2 atmosphere at a heating rate of 50 °C min . 

At this time, replace the Nj atmosphere with air and heat the sample to 700 °C at a heating rate of 2.5 °Cmin.  

Obtain the content of the carbon black obtained from the resulting TG curve by taking into account the mass loss due to the oxidation of the polymeric residue. The entire above run will take approximately 2.5 h. 

If it is difficult to determine the initial mass loss of the carbon black on the TG curve, the lowest valley point of DTG curve can be used. The average deviation of the resulting value obtained using this method from the added amount of carbon black is approximately 3%. 

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The double heating method is interpreted graphically in Figure 5.37. The procedure is follows ... 

In 2002, Chiang and coworkers[124] developed a new scheme for the confined synthesis of TPA-silicalite nanocrystals. The surfactant cetyltinmethylammonium bromide (CTAMeBr) (in ethanol solution) was added to the single- and double-heated TPA-silicalite precursor sols (SHPS and DHPS), and the mixture was flocculated at a certain pH value to collect the nano-size silicate species in the precursors, and then dried. The dried precursor/surfactant hybrid was pressed into pellets and then steamed in a stainless steel autoclave at 110 150°C for 7 36 h. Finally, the product was calcined to remove the surfactants and TPA. The particle sizes of silicalite-1 produced in this method are about 30 nm. The study indicates that the nanoparticles collected by surfactants already exhibit the structural features of MFI. They crystallize entirely to form silicalite-1 nanocrystals after steam treatment at 110 150 °C. This new solid-phase approach provides a way to synthesize MFI nanocrystals without the problem of separation and collecting nanocrystals from suspension, and it also avoids the large consumption and cost of special mesoporous templates used in the confined-synthesis methods. 

The Wittig olefination, a widely used transformation for the construchon of carbon-carbon double bonds, has been improved. Some difficult reacbons of stable phosphorus ylides with ketones in the absence of solvent are accelerated by MW irradiation using a domestic MW oven and the procedure affords improved yields compared with reactions carried out by conventional heating methods (Scheme... 

Samples for measurement were parallelepipeds (5 x 5 x 30 mm). Results are listed in Table IV and shown in Fig. 1. They were obtained with the double flux method, which permits the elimination of first order systematic errors owing to the parasitic heat leak. Measurements below 7 K were taken with superconducting heating leads to reduce the heat leak. The temperature difference was measured with a gold/iron - Chromel thermocouple, xsrhich constitutes a thermal shunt. This must be taken into account to calculate the sample thermal conductivity. At values near 10 W/cm K at 2 K, for instance, the calculated correction amounts to nearly 30%. 

This is also done in combination with a preheater waste heat boiler by applying the double path method . 

In another recent paper (Sawae et al., 2005), polyethylene glycol microspheres were prepared using an oil-in-water-in-oil double-emulsification method to encapsulate lipase complexes. The PEG microspheres exhibited heat-resistant properties that are advantageous when compared with the lipase complex itself dissolved in organic solvent. It was found that PEG microspheres retained high enantioselectivity in the esterification of phenyl ethyl alcohol and lauric acid in isooctane. The immobilized lipase complexes in the PEG microspheres can be easily recovered, and their activity remained preserved up to 10 reuses. 

Thionyl chloride method. Mix 100 g. of pure p-nitrobenzoic acid and 125 g. (77 ml.) (1) of redistilled thionyl chloride in a 500 ml. round-bottomed flask. Fit the flask with a double surface reflux condenser carrying a calcium chloride (or cottou wool) guard tube and connect the latter to an absorption device e.g.. Fig. II, 8, c). Heat the flask on a... 

Mono-, di-, and trivalent bromides and iodides may be made by methods similar to the chlorides. The lower valence salts also disproportionate in water. Indium trifluoride [7783-52-0] InF., is sparingly soluble in water. It forms an ammonium double salt, SNH F TnF. [15273-84-4] which decomposes on heating to indium nitride [25617-98-5] InN. 

Pure zirconium tetrachloride is obtained by the fractional distillation of the anhydrous tetrachlorides in a high pressure system (58). Commercial operation of the fractional distillation process in a batch mode was proposed by Ishizuka Research Institute (59). The mixed tetrachlorides are heated above 437°C, the triple point of zirconium tetrachloride. AH of the hafnium tetrachloride and some of the zirconium tetrachloride are distiUed, leaving pure zirconium tetrachloride. The innovative aspect of this operation is the use of a double-sheU reactor. The autogenous pressure of 3—4.5 MPa (30—45 atm) inside the heated reactor is balanced by the nitrogen pressure contained in the cold outer reactor (60). However, previous evaluation in the former USSR of the binary distiUation process (61) has cast doubt on the feasibHity of also producing zirconium-free hafnium tetrachloride by this method because of the limited range of operating temperature imposed by the smaH difference in temperature between the triple point, 433°C, and critical temperature, 453°C, a hafnium tetrachloride. 

When heated in the presence of a carboxyHc acid, cinnamyl alcohol is converted to the corresponding ester. Oxidation to cinnamaldehyde is readily accompHshed under Oppenauer conditions with furfural as a hydrogen acceptor in the presence of aluminum isopropoxide (44). Cinnamic acid is produced directly with strong oxidants such as chromic acid and nickel peroxide. The use of t-butyl hydroperoxide with vanadium pentoxide catalysis offers a selective method for epoxidation of the olefinic double bond of cinnamyl alcohol (45). 

Heaters. The preferred methods for heating are a double-jacket heated tank, nonmetaUic heat exchangers, quartz heaters, or Teflon-coated low watt density stainless steel heaters. Localized overheating must be avoided. 

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