Decomposition behavior

In this section we discuss the initiation step of free-radical polymerization. This discussion is centered around initiators and their decomposition behavior. The first requirement for an initiator is that it be a source of free radicals. In addition, the radicals must be produced at an acceptable rate at convenient temperatures have the required solubility behavior transfer their activity to... 

SolubiHty parameters of 19.3, 16.2, and 16.2 (f /cm ) (7.9 (cal/cm ) ) have been determined for polyoxetane, po1y(3,3-dimethyl oxetane), and poly(3,3-diethyloxetane), respectively, by measuring solution viscosities (302). Heat capacities have been determined for POX and compared to those of other polyethers and polyethylene (303,304). The thermal decomposition behavior of poly[3,3-bis(ethoxymethyl)oxetane] has been examined (305). 

An MAI composed of polycaprolactam was investigated on its thermal decomposition behavior to develop easy decomposable polymers, the addition of oxidative deterioration was needed [72]. 

The approach taken in the development of an analytical model for the combustion of double-base propellants has been based on the decomposition behavior of the two principal propellant ingredients, nitrocellulose and nitroglycerin. The results of several studies reviewed by Huggett (HI2) and Adams (Al) show that nitrocellulose undergoes exothermic decomposition between 90° and 175°C. In this temperature range, the rate of decomposition follows the simple first-order expression... 

Schwartz, R. W. Payne, D. A. Holland, A. J. 1989. The effects of hydrolysis and catalysis conditions on the surface area and decomposition behavior of polymeric sol-gel derived PbTi03 powders. In Ceramic Powder Processing Science, edited by Hausner, H. Messing, G. W. Hirano, S. Deutsche Keramische Gesellschaft. pp. 165-172. 

The decomposition behavior of formic acid on the close-packed Ru(lOTO) surface parallels the reaction on nickel, except that the autocatalytic process was not observed (lOJ). Water was desorbed at 183 K by apparent second-order kinetics following adsorption of HCOOH at 100 K. Subsequent desorption of Hj, COj, and CO suggested the formation of the surface anhydride. The rate constant for decomposition was 2.6 x 10 sec exp —26.9 kcal/mol// r. ... 

The same decomposition path was observed for KBH by Stasinevich and Egorenko [178] except that the melting and decomposition temperatures were much higher (by about 100°C). We performed ball milling for 5 h on the as-received NaBH but without any effect on its decomposition behavior. This is most likely due to the fact that NaBH exhibits a high structural stability during... 

Since dithio- and selenocarbamates and their derivatives are used so widely in the deposition of thin films and nanoparticles that a mechanistic study of their decomposition behavior was carried out by O Brien et al. [ 107]. Wold et al. [78] studied the decomposition products of Zn(S2CNEt2)2 using gas-chromatography mass spectrometry (GC-MS) and their reported deposition path shows clean ehmination of ZnS from the precursor (Eqs. 1 and 2 below). However, the proposed decomposition route is somewhat different to the step-by-step fragmentation observed in the electron-ionization mass spectrometry (EI-MS) of the compoimd, (Eq. 3). This difference can be attributed to inherent differences between the two techniques. 

A study was conducted to find out the effect of addition of these nitroplasticizers on ballistic properties of AP and RDX/HMX filled CMDB propellants. The data generated clearly indicated that the incorporation of nitroplasticizer, that is, 1 1 mixture of BDNPF and BDNPA in place of diethyl phthalate (DEP) for AP and nitramine based CMDB propellants improved the burn rates as well as /sp and thermal decomposition behavior of these propellant formulations [193]. 

The other series of experiments, particles covering with different Ca(OH)2 fed into the calcinator to investigate the thermal decomposition behavior in the calcinator at 300,... 

From the analyses of NMR and electron-spray ionization mass (ESI-MS) spectroscopy, the polymers obtained from the polymerization of cyclic disulfides were found to be a cyclic structure [202], The cyclic structure consisting of poly(DT) is assumed to be formed by a backbiting reaction of propagating species [203]. Thermal and mechanical properties of the polymers, and decomposition behaviors of the polymers demonstrate that the polymers obtained from thermal polymerization of cyclic disulfides include a polycatenane structure. From polymerization of cyclic disulfides in the presence of cyclic polyethylene oxide), a polycatenane consisting of two different cyclic polymers was obtained [199]. Thus, poly(DT) contains spatial entanglements of cyclic polymers with each other (a polycatenane structure was presumed) (Fig. 61). 

Solid Cu2OCl2 products formed by the ultrasonic nozzle were subsequently heated from room temperature to 700°C to investigate its decomposition behavior as a function of temperature. While several mass numbers were monitored as a function of time and reaction temperature, the oxygen peak at mass number 32 is shown in Figure 6. The peak area was determined and converted to an amount of oxygen via a calibration curve. As can be seen the oxygen signal started near 400°C and ended near 550°C. The calibration showed that the peak area corresponded to 100% of the theoretical amount. 

The quantitative high-temperature chemistry of chlorine oxysalts is rather underdeveloped. There are very few thermodynamic data for these compounds above 298 K. Even when they exist, they must be applied cautiously, since there may be kinetic rather than thermodynamic factors that determine decomposition behavior. Although the thermal decomposition of a few compounds has been studied very carefully (e.g., the KC104 literature extends back for more than a hundred years because of the compound s use in explosives), the bulk of the available information is qualitative or semiquantitative. In recent years this has changed somewhat with increasing use of automated techniques such as DTA and TGA. Many of the reactions are complex, with mechanisms frequently controversial and not completely worked out. Decomposition products may depend on experimental conditions e.g., salts are frequently prepared by dehydration of their hydrates, and residual water may affect the course of the decomposition. 

Furthermore, the effect of hydrated fillers on polymer fire retardancy will depend not only on the nature of the filler, including its particle characteristics (size, shape, and purity) and decomposition behavior, but also on the degradation mechanism of the polymer, together with any filler/ polymer interactions that might occur, influencing thermal stability of the polymer and possible char formation. 

Performance in excess of the predicted value is due to the well-established decomposition behavior of hydrazine in which ammonia, nitrogen, and hydrogen are the decompositions products rather than only nitrogen and hydrogen as predicted from equilibrium considerations. The effect in this case amounts to the liberation of about 11 kcal/mole of hydrazine more energy in the actual decomposition than in the equilibrium predicted decomposition. 

The key feature of Inisurfs is their surfactant behavior. They form micelles and are adsorbed at interfaces, and as such they are characterized by a critical micelle concentration (CMC) and an area/molecule in the adsorbed state. This influences both the decomposition behavior and the radical efficiency, which are much lower than those for conventional, low molecular weight initiators. Tauer and Kosmella [4] have observed that in the emulsion polymerization of styrene, using an Inisurf concentration above the CMC resulted in an increase in the rate constant of the production of free radicals. This was attributed to micellar catalysis effects as described, for example, by Rieger [5]. Conversely, if the Inisurf concentration was below the CMC the rate constant of the production of free radicals decreased with an increase in the Inisurf concentration, which was attributed to enhanced radical recombination. Also note that a similar effect of the dependence of initiator efficiency on concentration was reported by Van Hook and Tobolsky for azobisisobutyronitrile (AIBN) [6]. 

The alkylated BDHC complexes are very unstable in general and cannot be isolated in pure form from the reaction mixture. A large portion of an alkylated product decomposes during the extraction procedure with organic solvents. Thus, the decomposition behavior of the alkylated BDHC complexes was investigated as they were prepared in aqueous media, after decomposition of the excess NaBH4 with acid in the presence of excess alkyl halide. An alkylated BDHC complex also can be prepared by the reaction of [Co(II)(BDHC)]C104 with an alkyl iodide under alkaline condition (pH 12) the disproportionation reaction yields the Co(III)(BDHC) species and an alkylated BDHC complex. 

In maximizing performance, or at least meeting performance requirements of extruded plastics as well as minimizing cost to extrude products it is important to understand the processing behavior of the different plastics. In producing the different extruded products certain plastics can be used. An understanding of factors such as their rheological to decomposition behaviors as well as problems that can develop provide information that will make it easier to extrude products (Chapters 1, 2, 3, and other chapters). 

The CVD decomposition behavior of binuclear [Pd2(PMe3)6](hfac)2 involves the disproportionation shown in equation 3 . Solid-state thermolysis (140 °C, vacuum) of [Pd2... 

M. F. Ali, and M. N. Siddiqui, Thermal and catalytic decomposition behavior of PVC mixed plastic waste with petroleum residue. Journal of Analytical and Applied Pyrolysis, 74, 282-289, (2005). 

Examination of the data on C02 and pyrolytic water evolution may provide some insight into the thermal decomposition behavior of specific organic and inorganic structures in the parent coals. Some C02 may arise from the decomposition of inorganic matter within the coal. It also has been suggested (16) that decomposition of carboxyl groups in the... 

TCE decomposition behaviors in the column with and without the adsoibent were examined. As shown in Figure 3, much ster TCE decon iosition was observed... 

Shallow geochemical environments consist of solid, aqueous, and air reservoirs and their interfaces. Hydrocarbon compounds partition into these various reservoirs in a manner determined by the stmcture and physical properties of the compounds and the media, and the mechanism of hydrocarbon release. The structure and physical properties of the compounds and media understandably impact their sorption, solubility, volatility, and decomposition behavior (e.g., Schwarzenbach et al., 1993). In addition, hydrocarbon partitioning in real systems is holistically a disequilibrium process hence, the distribution of hydrocarbons depends as much on the pathway taken as on the final physical state of the system (e.g., Schwarzenbach et al., 1993 Luthy et al., 1997). Shallow aquatic systems may tend towards some equilibrium distribution (Figure 10), but this is seldom, if ever, truly attained. 

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