Qualitative identification by pyrolysis - gas chromatography

For the general examination of a wide range of rubbers or plastics, packed column pyrolysis is more than adequate. However, for comparison of one batch of rubber with another batch of the same rubber, the detail obtained from capillery pyrolysis gas chromatography will probably give the best results because minor details can be compared. Applications for pyrolysis are vast and include all types of synthetic polymers, rubbers and plastics, as well as latexes, paints and varnishes in fact, almost any sample that contains involatile organic material that can be contained in a tube or coated onto a platinum ribbon so that it may be pyrolysed. 

May et aP have used this Curie point filament pyrolyser to produce pyrolysis -gas chromatograms for various polymers (Method 106). 

Voigt employed the platimun filament pyrolyser. This unit is attached directly to the gas inlet of Ae gas chromatograph for the examination of ethylene - propylene copolymers. 

Pyrograms will differentiate between random copolymers and block polymers or polymer mixtures. Presence of foreign monomer may interrupt chain transfer processes involved in the degradation. Similar products result but their quantities as determined from peak heights are different. 

Systematic identification of plastics was attempted by Nelson et aP by pyrolyzing 0.2 - 0.5 mg samples for 10 s at 650 - 750 C in an argon gas chromatograph using a 4 ft column of 5% silicone oil on Chromosorb W. Similar plastics were distinguished from pyrograms obtained at two different temperatures. 

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