Thermal degradation of polymers. XVII. Thermal analysis of polyquinazolones and related systems

Ghafoor, Abdul; Still, R. H.

doi:10.1002/app.1977.070211106

Cited by 9 publications

(2 citation statements)

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“…Extensive studies have been carried out on the mode of insertion of peroxy linkages in polymers.1-3 On the other hand, unfortunately, our understanding on the complex phenomena pertaining to the effect of weak links on the thermal stability and photostability of polymers is very poor.4-5 Besides the peroxy links, other weak links of group VIA elements, namely, the disulfide and diselenide linkages, also affect the thermal stabilities of the polymers. [6][7][8] We report here a comparative study as to how the weak links of group VIA elements influence the thermal degradation behavior of polymers.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization, and thermal degradation studies on group VIA derived weak-link polymers

Kishore¹,

Ganesh²

1993

Macromolecules

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Polymers containing group VIA derived weak links, viz. poly (styrene disulfide) (PSD), polystyrene tetrasulfide) (PST), and poly (styrene diselenide) (PSDSE), have been synthesized. The polymers PSD and PST were characterized by NMR, IR, UV, TGA, and fast atom bombardment mass spectrometric (FABMS) techniques. The presence of different configurational sequences in PSD and PST were identified by 13C NMR spectroscopy. PSDSE, being insoluble in common organic solvents, was characterized using solid-state 13C NMR (CP-MAS) spectroscopy. Thermal degradation of polymers under direct pyrolysis-mass spectrometric (DP-MS) conditions revealed that all the polymers undergo degradation through the weaklink scission. A comparative study of the pyrolysis products of these polymers with that of polystyrene peroxide) (PSP) revealed a smooth transformation down the group with no monomer (styrene or oxygen) formation in PSP to only styrene and selenium metal in PSDSE. This trend of group VIA is explained from the energetics of the C-X bond (X -O, S, and Se) which also seems to be important in addition to the weak X-X bond cleavage. In PSP and PSD, the behavior is also explained from the energetics of the alkoxy and thiyl radicals. The unique exothermic degradation in PSP compared to endothermic degradation in PSD and PSDSE is explained from the nature of the products of degradation.

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Section: Introductionmentioning

confidence: 99%

Synthesis, characterization, and thermal degradation studies on group VIA derived weak-link polymers

Kishore¹,

Ganesh²

1993

Macromolecules

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“…One of the most serious draw backs of heat resistant polymers is their insolubility and intractability conferred by the very structural features desirable for high thermal stability. In the case of the most promising heat resistant polymers such as polyimides, 1 -3 the most commercially successful of all the heat resistant polymers, polybenzimidazole, 4 polyquinazolones, 5 poly-imidazolepyrrolones, 6 and polyquinazolinediones, 7 the synthesis involved a novel two steps process in which soluble and fabricable high molecular weight prepolymers were first prepared. Rigid stable rings were then formed by thermally or chemically induced cyclodehydration or cyclisation of reactive group attached to the prepolymer chain to give an insoluble, infusible and intractable polymer.…”

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X-Ray Photoelectron Spectroscopic Studies of Polyquinazolones: An Assessment of the Degree of Cyclization

Chan

Hor

Sim

et al. 1990

Polym J

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ABSTRACT:Prepolymers of polyquinazolone have been prepared from 4,4' -diaminodiphenyl-3,3' -dicarboxylic acid and aromatic diacetoamido compounds by melt condensation. Optimum preparative conditions were established for each individual system on the basis of reduced viscosity and thermogravimetry (TG) results. The soluble prepolymers were converted to the quinazolone structure by thermal cyclization under two heating programmes. A significant amount of uncyclized carboxylic groups have been identified by X-ray photoelectron spectroscopy (XPS). Quantitative measurements of the C = O/COOH ratio at the surface of the resultant polymers have been carried out by XPS, which provide a reliable measure of the degree of cyclization. Comparison of XPS results with TG data indicates a direct correlation between degree of cyclization on the polymer surface and thermooxidative stability of the bulk polymer.KEY WORDS Heat Resistant Polymer / Polyquinazolone / X-Ray Photoelectron Spectroscopy / Thermogravimetry / Degree of Thermal Cyclization / Thermooxidative Stability / thermal stability. One of the major limitations of synthetic polymers is their poor thermooxidative stability compared with other materials, especially metals, alloys and ceramics. To overcome this problem as well as to meet the rapid development of atomic reactors and space aviation, a new generation of heat resistant polymers has been prepared during the past decades.The attempt to synthesize polymers capable of withstanding prolonged exposure to elevated temperature, has been three pronged.1. To improve the existing polymers by structural modification. 2. To devise new organic systems tailored to resist the effect of heat and oxidation. 3. To synthesize new classes of inorganic and semi-inorganic polymers of highIn the second mode of attack, the most fruitful of these three lines of research, a whole new generation of carbon-based polymers with inherently rigid chains have been developed. The polymers were prepared by incorporating highly stable rigid, carboxylic and/or heterocyclic ring systems directly into the polymer chain. An infinite variety of such structures is possible, and many have been synthesized. One of the most serious draw backs of heat resistant polymers is their insolubility and intractability conferred by the very structural features desirable for high thermal stability. In the case of the most promising heat resistant polymers such as polyimides, 1 -3 the most commercially successful of all the heat resistant polymers, polybenzimidazole, 4 polyquinazolones, 5 polyt To whom correspondence should be addressed. 883

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Thermal degradation of polymers. Part XVIII. The synthesis and characterization of quinazolone pre‐polymers

Chan¹,

Still²

1978

J of Applied Polymer Sci

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SynopsisA series of quinazolone pre-polymers have been prepared from 4,4'-diaminodiphenyl-3,3'-dicarboxylic acid and aromatic diacetamido compounds by melt polycondensation. The pre-polymers have been characterized by combustion analysis, viscometry, vapor pressure osmometry, and thermal analytical methods (TG, DTA, and DSC). Structures have been elucidated by spectroscopic methods (IR and NMR). The thermal cyclization of these pre-polymers to the partial ladder polyquinazolone has been studied and optimized using IR, DSCDTA, TG, and evolved gas analysis. The cyclization behavior of these systems has been resolved in terms of concurrent dehydration and decarboxylation.

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Thermal degradation of polymers. XVII. Thermal analysis of polyquinazolones and related systems

Cited by 9 publications

References 0 publications

Synthesis, characterization, and thermal degradation studies on group VIA derived weak-link polymers

Synthesis, characterization, and thermal degradation studies on group VIA derived weak-link polymers

X-Ray Photoelectron Spectroscopic Studies of Polyquinazolones: An Assessment of the Degree of Cyclization

Thermal degradation of polymers. Part XVIII. The synthesis and characterization of quinazolone pre‐polymers

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