Organic particulate analysis of isocyanate compounds

The technique of Organic Particulate Analysis (OPA) has been employed to investigate the thermal decomposition of a series of isocyanate compounds; OPA measures the temperature at which particulate or aerosol matter is emitted from a heated organic substance. Of the eighteen isocyanate compounds investigated, seventeen showed strong organoparticulation activity below 200 °C. With the possible exception of four isocyanates, no obvious correlation exists between the OPA values and the melting or decomposition point of the compound.In an attempt to characterize the nature of the particulate matter derived from these compounds, mass-spectral data were obtained at thermoparticulation. Most of the massspectral particulate analyses showed the presence of very polar species (such as diethylamine) which were capable of exhibiting hydrogen-bonding properties. This hydrogen bonding gives rise to particulate matter of sufficient size to be detected by an ion chamber instrument. The ability of phenols to particulate, whereas thiophenols do not particulate, is discussed.