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04/Aug/2017
Recycling of plastic waste - curse or a blessing?
In our fast-paced „throwaway society“
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31/May/2017
Plastics for E&E applications, “fuse box meets dryer” 2017 in Würzburg
As in previous years „Kunststoffzentrum (SKZ
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01/Aug/2016
pinfa's first workshop in China confirms interest in halogen free FRs
In June 2016, over 250 people from academia, indus
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02/Nov/2015
1st International Asia-Oceania Symposium on Fire Safety Materials Science and Engineering (AOFSM’1 2015)
The 1st International Asia-Oceania Symposium on Fi
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19/Oct/2015
European fire tests for cables in building and CE-marking
In 2008, in the context of the Construction Produc
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02/Sep/2015
Electrical fires and fire safety requirements for E&E equipment
In a U.S. statistical overview from NFPA[i] on ele
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Fire initiation and combustion process

When does it burn?

The fire triangle demonstrates that three factors

  • fuel
  • heat
  • air (oxygen)

must coincide in order for anything to burn.


The combustion process

The three factors mentioned above are related to each other in the combustion process: the combustion of plastics will be taken as an example in the following.

The combustion of plastics is a process comprising many steps and basically initiated by a heat source initiating the decomposition of the polymer. These two steps, heating and decomposition of the polymer consume energy (endothermic process) for overcoming the high binding energies between individual atoms (200 to 400 kJ/mole).

Combustible gases are formed, which mix the oxygen of the air and ignite. This leads to the exothermic part of the process, i. e. flame propagation and heat release. Pyrolysis of the polymer is reinfoced by thermal feedback (heat release), which fuels the flame at an increasing level. The flame is supported by extremely high energy H· and OH· radicals, which confer a high velocity to the flame.


Flame retardants may inhibit the chemical reactions in the flame by removing the high energy radicals, or initiate the formation of a charred layer on the surface. Thus, the polymer is protected against the attack of heat and oxygen of the air and prevents the formation of flammable gas mixtures.