Pyrolysis-Molecular Weight Chromatography of Polymers: A New Technique

A pyrolyzer with programming capability has been coupled in series with a thermal conductivity cell and a mass chromatograph. The thermal conductivity cell gives the flexibility for selective trapping of decomposition products, and also provides data that are complementary to thermogravimetric and differential thermal analyses. The mass chromatograph is composed of two gas chromatographs that are run parallel from a common injection port. Each chromatograph uses a different carrier gas and is equipped with a gas density balance detector. The instrument simplifies identification of mixtures of unknowns in directly providing molecular weights, absolute quantities, and gas chromatographic retention times of the constituents. In this respect, the present system is analogous to pyrolysisgas chromatography-mass spectrometry. Discussion of the technique and its application to the investigation of the thermal degradation of low-density polyethylene are presented.