Thermal gravimetric analysis polymers

The chemical name for such materials is poly(bisbenzimid-azobenzophenan-throlines) but they are better known as BBB materials. Such polymers have a Tg in excess of 450°C and show only a low weight loss after aging in air for several hundred hours at 370°C. Measurements using thermal gravimetric analysis indicate a good stability to over 600°C. The main interest in these materials is in the field of heat-resistant films and fibres. 

ADMET polymers are easily characterized using common analysis techniques, including nuclear magnetic resonance ( H and 13C NMR), infrared (IR) spectra, elemental analysis, gel permeation chromatography (GPC), vapor pressure osmometry (VPO), membrane osmometry (MO), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The preparation of poly(l-octenylene) (10) via the metathesis of 1,9-decadiene (9) is an excellent model polymerization to study ADMET, since the monomer is readily available and the polymer is well known.21 The NMR characterization data (Fig. 8.9) for the hydrogenated versions of poly(l-octenylene) illustrate the clean and selective nature of ADMET. 

Thermal Analysis - Differential Scanning Calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to characterize the thermal properties of the polymers synthesized. DSC analysis was performed on a Perkin-Elmer Differential Scanning Calorimeter, Model 2C with a thermal analysis data station. Thermal gravimetric analysis (TGA) was carried out on a DuPont thermal gravimeter, Model 951. From the DSC and TGA plots of poly (N-pheny 1-3,4-dimethylene-... 

The thermal behavior of the hyperbranched polymer 7, as well as that of the related tetra- and octanuclear dendrimers 1 and 2, was examined by thermal gravimetric analysis (TGA) and derivative thermogravimetry (DTG). The samples were heated at a ramp rate of 10 °Cymin under nitrogen atmosphere in the tenqierature range 25-8(K) °C. The major decompositions occur between 340 and 540 °C for the tetranuclear 1, and between 370 and 520 °C for the octanuclear 2, whereas for polymer 7 a faster rate of weight loss is observed at a higher (480 and 560 C) temperature range. The thermal stability of the network dendrimeric material 7 is... 

Other characterization methods that are of value are dynamic scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). A sample DSC is shown in the middle of Figure 15.2. Most cure reactions are exothermic, and the heat generated by cure can cause excessive heat to build up in the polymer if control is not exercised. DSC measures the generation of heat as a function of time and temperature. This can be used to predict the temperature at which the laminate will begin to cure (the onset of the peak in Fig. 15.2) and the temperature or time at which cure will be complete, further improving the selection of cure cycles to try. 

Of all the high temperature, high performance polymers, the benzobisazole rigid-rod polymers are one of the most thermally stable systems known. A variety of thermal techniques have been used to investigate their stability such as thermal gravimetric analysis (TGA), thermal gravimetric-mass spectrometry (TG-MS) and isothermal aging studies. A TGA plot shown in Fig. 4 is indicative... 

Chromophores must be thermally robust enough to withstand temperatures encountered in electric field poling and subsequent processing of chromophore/polymer materials. Chromophore decomposition temperatures can be assessed by techniques such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA and DSC measurements on neat chromophore samples in air will tend to yield decomposition temperatures lower than those for the same chromophores in hardened polymer lattices. Typically, to be useful for development of device quality materials, a chromophore must exhibit thermal stability of 250 °C or higher (with thermal stability defined as... 

Thermal stability of the vinyl ferrocene and ferrocene containing polymers plus unmodified polymer and neat ferrocene controls was determined by thermal gravimetric analysis at a heating rate of 10 /mln. The results are depicted in Figure 4. Apparently vinyl ferrocene imparts greater thermal stability to the BA/S/MAA polymer than the ferrocene additive. In fact, 1% vinyl ferrocene allows about a 50 C additional rise in temperature before decomposition relative to the unmodified polymer. Curiously, a substantial exotherm is present at 400 - 450 C (bump on curve) for the vinyl ferrocene modified polymers, but does not appear for the ferrocene modified polymers. 

In contrast the materials 47 with di-ferf-butylphenyl and 48 with first generation dendron side-chains were processable from toluene [73]. The degrees of polymerisation for these polymers were rather low, with the den-dronized polymer 48 having a Mn of only lOOOOg/mol (n = 10) probably due to the bulkiness of the substituents. Polymer 48 was also found to be exceptionally thermally stable, with no significant mass loss being observed in thermal gravimetric analysis (TGA) until 570 °C (cf. 463 °C for 89 [73]). 

Differential scanning calorimetry and thermal gravimetric analysis have been used by several authors (27,53) to show that plasma-derived polymers have no phase transitions until decomposition occurs. The remarkable thermal stability of these materials is evidenced by data which show that 80 wt.% of a film prepared from methyl chloride remains at 800 C and that 40 wt.% of a styrene derived film remains at 700°C. 

Thermal gravimetric analysis shown in Fig. 3, indicates some improvement in the thermal stability of the polymer cured with the appropriate additive. 

Thermal Analysis. Thermal and related properties of polymers can be determined by various procedures including thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), differential thermal analysis (DTA), torsional braid analysis (TBA), thermal mechanical analysis (TMA), and pyrolysis gas chromatography (PGC). 

The thermal gravimetric analysis of these polymers indicated onsets of decomposition between 250 and 350°C on heating in air at a rate of 10°C per min. This is well below that of the parent polymers. Differential scanning calorimetry was used to obtain the glass transition... 

Thermal stability of these polymers is very high in TGA (Thermal Gravimetric Analysis), they show decomposition not until 480 to 545 °C. 

Abstract In situ spectroscopy is an important tool to characterize polymers synthesized via a precursor route. Highly conjugated polymers such as po y(p-phenylene vinylene) (PPV) and PPV derivatives are commonly prepared from a precursor polymer because the final polymers are very insoluble and intractable. Preparation in the precursor form enables the polymer materials to be cast as films. The PPV polymers are obtained from the precursor forms using a thermal elimination reaction. The exact conditions of the reaction are important as they influence the properties of the resultant polymer. The details of this thermal elimination reaction have been analyzed using thermal gravimetric analysis (TGA) coupled with infrared analysis of the evolved gas products. In situ infrared spectroscopy of the precursor films during thermal conversion to the polymers has provided further details about the elimination reaction. We have characterized PPV synthesized from a tetrahydrothiophenium monomer (sulfonium precursor route) and via the xanthate precursor route. PPV derivatives under study include poly(2,5-dimethoxy-p-phenylene vinylene) and poly(phenoxy phenylene vinylene). 

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