Total Ion Counts

: POLYBUTENE (isotactic)

: see insert in spectrum; low molecular weight; density 0.91

: Scientific Polymer Products; USA

: solution in cyclohexane; 10 yg

: Teq 610°C; ty 5s; tj 10s; Eel 12eV; (Extranuclear 5000-1 Py-MS system)

remarks - In comparison with polyethylene (Spectrum H.l), polybutene shows a combination of thermal degradation and depolymerisation reactions. The thermal degradation reactions result in the formation of prominent alkene and alkadiene series. The depolymerisation reactions appear to proceed via unzipping, leading to the monomer peak at m/z 56, as well as via a backbiting mechanism, resulting in the marked trimer peak complex at m/z 166/168 (it should be interesting to study to what extent backbiting occurs in atactic and/or syndiotactic polybutene). Whether the peak at m/z 168 represents a linear or cyclic trimer is unknown, although the latter configuration would seem to be the most probable. The peak at m/z 166 must represent a dehydrogenated trimer, whereas the peak at m/z 139 is probably an electron impact fragment (M-29) of the trimer.

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