Instrumentation Used for Pyrolysis

2 INSTRUMENTATION USED FOR PYROLYSIS - Resistively heated filament pyrolyzers 

Resistively heated filament pyrolyzers have been used for a long time in polymer pyrolysis [1], The principle of this type of pyrolyzer is that an electric current passing through a resistive conductor generates heat in accordance with Joule s law  

The true temperature of a sample heated using a filament pyrolyzer can be quite different from the above profile temperature, significantly lower temperatures being recorded inside the samples [4]. In order to obtain a correct Teq, modern equipment uses a feedback controlled temperature system (see e g. [5] for a more detailed description of this type of pyrolyzer). Several other procedures for a precise temperature control of the filament are available, such as the use of optical pyrometry or thermocouples [6, 7], Special pyrolysis systems that allow programmed heated rates at different time intervals also are available [8]. 

The filament shape commonly used in resistively heated pyrolyzers is either a ribbon or a coil. The sample can be put directly on the filament or in a silica tube that fits in the 

There are several advantages of the resistively heated filament pyrolyzers compared to other types. They can achieve very short TRT values, the temperature range is large, and Teq can be set at any desired value in this range. Several commercially available instruments are capable of performing programmed pyrolysis, and autosampling capability is also available (such as the CDS AS-2500). 

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