Oxidative stability weight loss

According to Table 2.1, the highest stability concerning oxidation was reached with the Co/HB material, where combustion started first at 673 K. In the case of the Co/PL and Co/MW catalysts, weight loss initiates at 523 and 503 K, respectively. None of the catalysts showed major impurities (more than one oxidation peak) within TG analysis. 

PET requires special flame-retardant chemistry since the antimony oxide synergist that is normally used in combination with brominated flame retardants causes de-esterification of the PET chain and concomitant molecular weight loss. In place of antimony oxide, PET requires a sodium antimonate synergist. Another problem with antimony trioxide is that it decreases the thermal stability of the brominated flame retardant which then produces hydrobromic acid which degrades the PET. 

A further modification of the PMR-12F-71 resin comprises changing from the nadic endgroups to vinylphenyl endgroups, simply by using p-aminostyrene in the synthesis. This resin was called V-cap-12F-71 (see Fig. 37). The V-cap versions of PMR-II-50 (V-cap 11-50) and PMR-12F-71 (V-cap-12F-71) underwent a comparative long term thermal oxidative stability testing (112). Neat resin weight loss was measured at 343 °C in air over a period of 750 hours (Fig. 38). The data clearly indicate that the 12F-PMR resins exhibit excellent thermal oxidative stability and it also shows that the NE endcap is thermally less stable than the V-cap in the PMR-II series. 

The major concern was the thermal oxidative stability performance of the new resin. Weight loss measurements at 250,285 and 300 °C provided comparable low values at 250 and 285 °C. However, at 300 °C, the B1 composite exhibited a marketly lower weight loss than PMR-15. The temperature capability of B1 composite is obvious from Fig. 41, where the flexural properties of resins are plotted as a function of the ageing time at 285 °C. PMR-15 seems to be a superior resin in this test. 

It should be noted that PCMU based on cross-linked macroligands possess a relatively high chemical and thermal stability. The stability of poly(enol-ketonate) chelates obtained by oxidation of thin polyvinylacetate films increases in the series of mono-, di- and trivalent ions [122], the oxidation promoting the penetration of the metal ions into the deep film layers. The weight loss of Co and Mn polychelates based on the condensation products of stoichiometric amounts of 5,5 -methylene-bis-salicylaldehyde and 4,4 -diaminophenyl ether at 300, 500, and 600 °C is 2.1, and 0.5 8.0 and 9.8 25.0 and 27.5%, respectively [14b]. The stability, in the range between 275 and 640 °C, of chelates formed by the transition metals and condensation products of p-hydroxybenzoic acid, urea and formaldehyde follow the series [123] Fe(III)>Co(II)>Cu(II)>Ni(II)>V02(II)> Zn(II) Mn(II) > CML. 

The work described here supports the view that the chemical combination of metal ions with organic molecules leads to coordination complexes and polymers with enhanced stability with respect to weight loss, thermal degradation, or oxidation. Bis(8-hydroxyquinoline) derivatives were used to prepare a series of coordination polymers containing first-row transition metals, and the thermal stabilities of the polymers were evaluated. The influence of the structure of the organic molecule and the role of the metal are discussed. 

We have carried out thermogravimetric analysis of BC4N nanotubes in air. These nanotubes show high thermal stability and we observe no weight loss up to 900 °C (Fig. 6). Amorphous carbon nanotubes get completely oxidized before 750 °C. The high thermal stability of BC4N nanotubes is noteworthy. 

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