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Abstract  

The TG analyses are given for variously meta- and/or para-linked aromatic polyamides with various benzimidazolyl (BI)contents. The TG curves of the polymers were evaluated within 600C by use of an equation for multiple events. The TG curves of BI-substituted polymers are expressed for triple events, though the TG curves of unsubstituted polymer are expressed for double events. The amount of residue of BI-substituted polymers at 800C is larger than that of unsubstituted polymers, perhaps because moieties concerning BI degrade at higher temperatures.

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very poor due to the low melting point and/or glass transition temperature, which limit their application at high temperature. In our study, a new semi-aromatic polyamide (BO6) containing benzoxazole unit based on 5-amino-2-( p -aminophenyl) benzoxazole

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Abstract  

The TG studies are presented for isomers of benzimidazolyl-substituted polyamides (BIPA). The TG data are compared with those polyamides (PA) of identical backbones without substitution, in view of the mechanism of thermal degradation. The TG mass loss curves divided to three temperature ranges reflect the decomposition reactions in the respective temperature ranges: (1) cleavage of single bonds of nitrogen to aromatic ring, (2) random scission of single bonds, (3) condensation of the remained rings. Liberation of benzimidazole rings occurs in the temperature range (2). The final product, char, contains benzimidazole rings. Terephthaloyl-rich BIPA's retard liberation of benzimidazole from the decomposed polymer.

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Aromatic polyamides

VIII. Kinetic analysis of the thermal- and thermo-oxidative degradation

Journal of Thermal Analysis and Calorimetry
Authors: Y. Khanna and E. Pearce
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Abstract  

The polycondensation reactions between 4,4′-[sulphonyl bis(p-benzoyl)(p-phenyleneoxy)]dibenzoic acid (I) andp-phenylenediamine (II), 1,5-diaminonaphthalene (III), 4,4′-sulphonyldianiline (IV), 4,4′-diaminodiphenylsulphide (V) 4,4′-methylenedianiline (VI) and 4,4′-oxydianiline (VII) to form aromatic polyamides containing sulphone, ether and ketone linkages were attempted by a solid-solid interaction route. A stoichiometric 1∶1 molar ratio of solid reactants was dynamically heated directly in a TG/DSC apparatus, and simultaneous TG/FT-IR was performed to interpret the mechanism of reaction. The results suggest that the polycondensation is dependent on the diamine used. The formation of polyamide was successful when I interacted with II, III, VI and VII. The interaction with IV and V was in part successful because partial decarboxylation of the diacid, made unstable by the diamine, occurred before the condensation reaction.

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soluble in nonionic polar solvents, such as N , N -dimethylacetamide, DMA, dimethylsulfoxide, DMSO, etc., [ 1 , 2 ]. Aromatic polyamides having good solubility are industrially important, because of their ease of fabrication. Many aromatic polyamides

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Abstract  

Aromatic polyamides find many applications in diverse and critical areas due to their high thermal stability coupled with high mechanical properties. However most of such aramides are difficult to fabricate because of their limited solubility and high melting temperature. Improvements in processability have been reported by incorporating bulky pendant groups and aliphatic spacer groups. Similarly to improve the solubility of polymers approaches of incorporating silicon in main polymer chain and co-polymerization techniques were useful. We report the synthesis and characterization of a series of phenylated silicon containing aromatic–aliphatic polyamides from a mixture of 2, 5-bis (4-carboxy methylene phenyl)-3, 4-diphenyl thiophene (CMPDT) and bis-(4-carboxy phenyl) dimethyl silane (BCPDS) in various mole proportions, with commercial aromatic diamine. Thus a series of novel co-polyamides having pendant phenyl groups, methylene spacer and silicon moiety was prepared by judicious combination of (CMPDT); BCPDS and aromatic diamine; bis-(4-aminophenyl) ether (ODA), by direct polycondensation using Yamazaki’s phosphorylation method. These high molecular mass polyamides were obtained in high (89–98%) yields and had viscosities in the range of 0.23–0.57 dL/g in DMAc. Polyamides showed improved solubility in polar aprotic solvents, like NMP, DMAc, DMSO and DMF; had high thermal stability; with no mass loss below 335 °C.

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Poly(2-methylpentamethylene terephthalamide) (Nylon M5T) is a new high temperature aromatic polyamide developed by Hoechst Celanese. In this paper thermal properties of Nylon M5T chips, as well as as-spun and drawn fibers were studied by DSC, DMA, hot stage microscopy and WAXS.T g of the fully amorphous Nylon M5T is 143°C when measured by DSC;T g increases with crystallinity to 151°C. The temperature dependence of the solid and melt specific heat capacities has also been determined. The heat capacity increase at the glass transition of the amorphous polymer is 103.9 J °C−1 mol−1.T g by DMA for the as-spun fiber is 155°C, for a drawn fiber is 180°C. Three secondary transitions were observed by DMA in addition to the glass transition. These correspond to a local mode relaxation of the methylene groups at −120°C, onset of rotation of the amide-groups at −65°C and the onset of the rotation of the phenylenegroups (at 63°C). The crystallinity of Nylon M5T strongly depends on the rate of cooling from the melt. The isothermal crystallization data are melt temperature dependent: two-dimensional crystallization takes place when the samples are crystallized from higher melt temperatures, and this phase changes into a spherulitic structure during cooling to room temperature. Spherulitic crystallization occurs when lower melt temperatures are used. This polymer has three crystal forms as indicated by DSC, DMA and WAXS data. The crystal to crystal transitions are clearly visible when amorphous samples are heated in the DSC, or the DMA curves of as-spun fibers are recorded. It is experimentally shown that a considerable melting of the lower temperature crystal forms takes place during the crystal to crystal transitions. The equilibrium melting point as measured by the Hoffman-Weeks method, has been determined to be 339°C.

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. 18. Gu H , He JM , Hu J , Huang YD . Thermal degradation kinetics of semi-aromatic polyamide containing benzoxazole unit . J Therm Anal Calorim. doi: 10.1007/s10973

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aromatic polyamide fibers and polyurethane, the demand for m -phenylenediamine is growing [ 4 ]. Because of its wide applications, the production of m -phenylenediamine is gaining importance; and hence has increased the need for the reduction of m

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