Poly thermooxidative stability

It has been determined from X-ray diffraction measurements that polycarbonate containing Bisphenol AF moiety are all amorphous.6 The (Tg) of poly(carbonate)s increases with an increase in hexafluoroisopropylidene unit from 149°C for Bisphenol A poly(carbonate) (3) to 169°C for Bisphenol AF poly(carbonate) (2) (Table 9.3).6 Thermooxidative stability is also improved by the introduction of fluorine atoms into the isopropylidene units. The 10% weight-loss temperature (DT10) increases from 429 to 460°C and the residual weight (RW) at 500°C goes from 37 to 57% by perfluorination of the isopropylidene units. 

The thermooxidative stability is improved by increasing the hexafluoroiso-propylidene unit content.12 The DTi0 in air is raised from 363°C for Bisphenol A poly(formal) (6) to 398°C for Bisphenol AF poly(formal) (7), and the RW at 500°C is increased from 48 to 73%.12... 

Thermooxidative stability of the fluorine-containing poly(ether ketone) (11) and poly(sulfide ketone) (13) from 15 is very high. The 5% weight-loss temperatures (DT5) are 391 and 436°C for poly(ether ketone) and poly(sulfide ketone) analogues having no fluorine atoms, whereas those of poly(ether ketone) (11) and poly(sulfide ketone) (13) are higher than 500°C. 

The cured or fully imidized polyimide, unlike the poly(amic acid), is insoluble and infusible with high thermooxidative stability and good electrical-insulation properties. Thermoplastic polyimides that can be melt processed at high temperatures or cast in solution are now also available. Through an appropriate choice of the aromatic diamine, phenyl or alkyl pendant groups or main-chain aromatic polyether linkages can be introduced into the polymer. The resulting polyimides are soluble in relatively nonpolar solvents. 

The thermal and thermooxidative stability of poly(vinyl methyl ether) (PVME) was described in Section 3.4.2. PVME was a component in some... 

Despite all the synthetic and processing efforts, composite materials containing poly(phenylquinoxaline) network matrices remain in very limited use. This is due to several reasons. Among them, one can enumerate the costs of monomers and of synthesis, lower than expected thermooxidative stability [598], reduced demand from the defense industry and, most important, the suspect carcinogenicity of the pivotal monomer 3,3 -diaminobenzidine [597]. The verified or suspect carcinogenicity of essentially all aromatic ortho-diamines makes it highly unlikely for poly(phenylquinoline) polymers and reactive oligomers to be in broad use in the future unless a new synthetic route to quinoxalines is found in which aromatic ortho-diamines are not used. 

Omega-SLllyl polycarbonates have been hydrosilated with either tertiary silanes or ym-tetramethyldisiloxane to yield silylated polycarbonates or polycarbonate-disiloxane-polycarbonate triblock copolymers.The siloxane-containing polymers exhibit relatively lower Tg and higher thermooxidative stability compared with bisphenol A polycarbonate. Hydrosilation of allyl-terminal poly(alkyleneoxide-co-sulfone) in 1 1 or 2 1 ratio with hydride-terminal polysiloxane leads to ABC and (AB)2C type block-terpolymers, respectively. DSC studies indicate microphase separation, while TGA data point to higher thermal stability for the siloxane... 

Fig. 80. Dependence of the gas evolution in the thermooxidative destruction of poly formaldehyde on the ratio of stabilizing additives (polyamine and inhibitor 22-46 at a summary ratio of 2.5%). T = 200 C Pq = 200 mm Hg. 1) 80 min after the beginning of the process 2) 100 min after the beginning of the process.

In air, the thermooxidative degradation and stability of commercial and laboratory made polyhydroxyalkanoates such as the homopolymer poly(3-hydroxybutyrate) and the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was investigated by Carraso et al. [20]. It was indicated that the presence of hydroxyvalerate within the copolymer led to a thermally more stable material (with an increase of 14°C). 

Botelho, G., A. Queirds, and P. Gijsman, Thermooxidative studies of polyfether-esters) 1. Copolymer of poly(butylene terephthalate) and polyfethylene oxide). Polymer Degradation and Stability, 67(1) p. 13. 2000. 

D. Laachachi, M. Ferriol, M. Cochez, D. Ruch, and J.-M. Lopez-Cuesta, The catalytic role of oxide in the thermooxidative degradation of poly(methyl methacrylate)-Ti02 nanocomposites. Polymer Degradation and Stability, 93 (2008), 1131-7. 

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