Analysis of polymers by pyrolysis/chemical ionization mass spectrometry

Two addition‐type polymers, polystyrene and polypropylene, and two condensation‐type polymers, poly(ethylene terephthalate) (Mylar) and poly(hexamethylene adipamide) (nylon‐6,6), were pyrolyzed directly in the ion source of a mass spectrometer by chemical ionization (CI) to reduce fragmentation. The spectra are relatively easy to interpret because most ion peaks occur at a mass corresponding to the ion formula M±H or M + 3H, where M is the formula of a fragment of the original polymer chain. Oligomer peaks were observed for the addition‐type polymers. The intensities of the protonated dimer and monomer were measured as a function of time for styrene (S) and propylene (P). It was found that essentially all the HS+2 was produced by the reaction of HS+ with S, but at least part of the HP+2 was formed by proton transfer to P2. The absence of the analogous reaction in styrene is presumably a result of the reduced volatility of S2.