Massenspektrometrischer Nachweis des cyclischen Trimeren im Polyäthylenterephthalat

Abstract

ZUSAMMENFASSUNG :Beim direkten Abbau von kommerziellem Polyathylenterephthalat im Massenspektrometer IaBt sich bei Temperaturen unterhalb des einsetzenden thermischen Abbaus des Polymeren das zu etwa 1 % enthaltene cyclische trimere Athylenterephthalat ohne vorherige Isolierung nachweisen und durch Vergleich mit den EI-und FD-Massenspektren eines authentischen Trimeren identifizieren. SUMMARY:By direct pyrolysis of commercial polyethyleneterephthalate in the mass spectrometer a content of about 1 % of the cyclic trimer ethyleneterephthalate is indicated at temperatures below thermal degradation of the polymer. The comparison with EI-and FD-mass spectra of the authentic cyclic trimer allows its identification without previous isolation. Einleitung

Thermal degradation and mass-spectrometric fragmentation processes of polyesters studied by time/temperature-resolved pyrolysis-field ionization mass spectrometry

“…Experimental details of the equipment and methodology used have been published.12•13 The samples were heated without any pretreatment from 50 °C to 700 °C in high vacuum at about 10-3 Pa with a heating rate of 1.2 °C s-1. In order to investigate whether low mass signals are formed some samples are additionally recorded in the mass range 15-500 Da (Da = dal ton). The spectrum shown for poly(hexamethylene sebacate) was composed from two measurements.…”

Mass spectrometric detection of cyclic oligomers in polyurethanes and polyureas

“…Loss of methyl isocyanate is an El process similar to the very frequent loss of C02 observed in the El spectra of cyclic esters, carbonates, and urethanes. 6,9,10 As mentioned above, since the cyclic oligomers identified here are novel compounds, after their detection in the polycondensation mixtures, they were isolated from the polymers by solvent extraction and subsequent crystallization. The mass spectra of the pure compounds were identical with those shown in Figures 2-5, and the NMR spectra were in agreement with formulas I-IV (Table I).…”