Characteristics of burning polymer materials

1. What is a polymer material

Macromolecular materials, also known as polymer materials, are materials based on polymer compounds. Polymer materials are materials composed of compounds with relatively high molecular weight, including rubber, plastics, fibers, coatings, adhesives, and polymer-based composite materials.

The structure of the polymer material determines its performance, and the control and modification of the structure can obtain polymer materials with different characteristics.

The unique structure, easy modification and easy processing characteristics of polymer materials make it have excellent performance that other materials can’t be compared and irreplaceable. Therefore, they are widely used in various fields of science and technology, national defense construction and national economy, and have become modern social life. Indispensable materials in all aspects of food, clothing, housing and transportation.

2. Combustion characteristics of polymer materials

(1) Polymer materials are generally exothermic when they burn, so the heat generation is relatively high.

The heat of combustion (that is, the heat emitted when 1g of material is fully burned) is mostly higher than that of wood and coal. For example, the burning of wood is 14.64KJ/g, coal is 23.01 KJ/g, and PVC is 18.05~28.03 KJ/ g, PE must reach 45.88~46.61 KJ/g.

(2) Large amount of smoke.

Macromolecule materials will release a large amount of smoke and harmful gases when they are burned, that is, the so-called smoky and outgassing properties. Not only does it generate a lot of heat during combustion, but it also needs more oxygen.

For example: The theoretical air volume required for the combustion of PVC plastic is 4.3m3/kg, and the PE is 11.4m3/kg. In actual combustion, it needs 2.5~2.8 times the theoretical volume. Therefore, when burning in a confined space , Due to insufficient oxygen supply, it is in a state of incomplete combustion and releases a large amount of smoke and harmful gases.

(3) Some polymer materials emit irritating, corrosive and toxic gases when they burn.

The decomposition, combustion, and outgassing process of the combustion process is the process of depolymerization and decomposition of polymer materials. Since the composition of different polymer materials is different, the harmful gases produced by depolymerization and decomposition during combustion are also different. The quantity is also different.

According to the materials mainly used in construction projects and daily life, the main products of thermal decomposition are hydrogen chloride, CO, CO2, NO2, NH3, SO2, benzene, aldehyde, formic acid, etc.

(4) The burning speed is different.

For example, polytetrafluoroethylene is non-flammable; polyvinyl chloride (PVC), polycarbonate (PC), chlorinated polyethylene (CPE), etc. are self-extinguishing; the burning speed of PE reaches 7.6-30.5mm/min; and PS Reach 12.7~63.5mm/min (horizontal surface burning speed).

(5) Deformation, softening, melting, dripping, etc. will occur during combustion, which have a great influence on the combustion state, often spreading and expanding the fire house, causing difficulties in extinguishing fire.