Maldi-tof Mass Spectrometry for the Characterization of Insoluble Carbonaceous Pitches
نویسندگان
چکیده
When carbonaceous pitches are used as raw materials for advanced carbon products, the molecular composition of the pitch acquires special importance. Not only does molecular composition affect the physical properties (e.g., softening point and viscosity) of the pitch, but it also affects the final properties, such as the strength and thermal conductivity, of the resultant carbon products. Unfortunately, the problem of determining fundamental molecular information for pitches is a difficult one that has yet to be completely solved. The classic technique for molecular weight distribution (MWD) determination is gel permeation chromatography (GPC), but the technique suffers from a number of disadvantages, including poor peak resolution; lack of adequate calibration standards; and the incomplete solubility of higher MW, mesogen-containing pitches in even aggressive GPC solvents. In principle, mass spectrometry (MS) techniques would be preferred for the analysis of pitches because the calibration is absolute and excellent resolution can be obtained. Unfortunately, most of these techniques (e.g., thermosprayMS and field desorption-MS) can only be applied to that fraction of pitch that is solventsoluble.
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