High decomposition temperatures

Azocarbonamide (I) Carbonamide N2, CO, CO2 190-230 220 Most widely used blowing agent in PVC and polyolefins. High decomposition temperature reduced by a variety of metal salts and oxides such as lead carbonate, lead phosphite and zinc oxide. High gas yield. Reaction products show little odour or discoloration. ... 

Novolac hydroxyl groups reacted with cyanogen bromide under basic conditions to produce cyanate ester resins (Fig. 7.41).105,106 Cyanate esters can thermally crosslink to form void-free networks, wherein at least some triazine rings form. The resultant networks possess high s, high char yields at 900°C, and high decomposition temperatures.105... 

Certain polyquinoxalines are thermo-stable with high glass transition temperatures up to 435°C,high decomposition temperatures (510-560°C) and notable oxidative resistance in air, but, on the other hand, they form highly viscous solutions that don t wet reinforcing fibres easily. 

In summary, on the one hand, metal borohydrides with low Pauling electronegativities (<1.3) exhibit high decomposition temperatures. Unfortunately, at the moment there is no viable approach on the horizon by means of which high decomposition temperatures of metal borohydrides could be reduced to a reasonable level, say, 200°C. On the other hand, metal borohydrides with the Pauling electronegativities... 

In systems where the propellants are used for thrust chamber cooling, properties related to heat transfer are important. Candidate propellants should have high specific heats, high thermal conductivities, high boiling points, high decomposition temperatures, etc. 

Table 15.2 shows the characteristics of the high-fluorine-content 6FDA/TFDB polyimide and KAPTON (nonfluorinated PMDA/ODA type polyimide, DuPont). The Tg of 6FDA/TFDB (335°C) is a little lower than that of PMDA/ODA because of its flexible -C(CF3)2- groups. However, 6FDA/TFDB has a high decomposition temperature of 569°C. 

The traditional flame retardant is based on organobromine compounds together with antimony trioxide as a synergist. Magnesium hydroxide is a good flame retardant due to its high decomposition temperature and smoke suppression properties. It is widely used in thermoplastic materials. However, magnesium hydroxide must be added in portions of some 60% to achieve a reasonable effect. 

Transition-metal nitrides have many properties that make them suitable for industrial applications, including high wear resistance, high decomposition temperature, and high microhardness. 

The problem with peroxides is that they are thermally unstable and do not survive the polymerization to reach the devolatilizer. Blakemore [23] solved this problem by using cyclic peroxides which have very high decomposition temperatures. Their thermal stability is due to the peroxide bond reforming once broken, because the two oxy radicals cannot escape each other so they recouple. If styrene happens to be in the vicinity of the cyclic peroxide while it is a dioxyradical, the diradical adds across the styrene double bond (Scheme 4.1). 

The materials obtained from polymerization of vinyl carbonates and carbamates are hard (but not brittle) clear thermoplastics with high decomposition temperatures, excellent chemical resistance and varying glass transition temperatures. 

An example of a TGA curve for one polymer with high decomposition temperature is given for poly(thiophene-2,5-diyl). The thermogram is shown in Figure 15.1.1, and was obtained using heating in air between 30 C and 830 C at a rate of 10 C/min. 

Since transition-metal-carbene complexes with amino substitution at the carbene carbon atom are thermally very stable, their application as aminocarbene transfer reagents necessitates the use of high decomposition temperatures which, in many cases, is disadvantageous for the isolation of cyclopropylamines. Thus, for example, the cyclopropylamine 13 was not isolated from the reaction of an aminocarbene-chromium complex 12 with acrylonitrile in cyclooctane at 140°C instead, the respective decomposition product 15 was obtained in low yield.It is well known that cyclopropylamines readily undergo thermal ring opening so this result is not surprising. 

The technique is restricted to materials which have a high decomposition temperature and can tolerate electron bombardment some complex materials (including many carbides and oxides) can survive the process with their stoichiometry relatively intact, but others decompose. 

A viscosity-molecular mass relationship [197] for one of the polynaphthoyl-enebenzimidazoles is presented in Table 28. Some characteristics of the synthesized polynaphthoylenebenzimidazoles containing 1,1-dihalogenethyIene groups are tabulated in Table 29. From analysis of the data, all the synthesized polynaphthoylenebenzimidazoles are soluble not only in sulfuric acid but in phenolic solvents as well. The majority of the systems are characterized by the high softening temperatures and high decomposition temperatures under the conditions of dynamic TGA,... 

In contrast to sustained release, some applications might require the liberation of the entire encapsulated material during a very short period of time, initiated by an external stimulus as temperature. To achieve this goal, azoinitiators with high decomposition temperatures were encapsulated in polymeric matrices [59]. The idea... 

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