To understand the principle of flame-retardant plastic, it is first necessary to understand the process of burning plastic.
     The burning plastic is an extremely complex process of thermal oxidation, resulting in burning of the basic elements for the heat, oxygen and combustible gas.
     It is generally believed that the burning plastic has gone through three stages as follows.
     In the first stage, hot off the course. From the external heat source or the source of the fire's heat led to the occurrence of plastic with too much change (that is, from a solid into a liquid) and the chemical changes.

     In the second stage, the process of thermal degradation. The process for the endothermic reaction, when the plastic is sufficient to absorb heat between atoms within molecules to overcome some of the key to small, plastic began to degradation. This is in response to the substance of the presence of oxygen in the air as a free radical chain reaction, the reaction of the results of the combustible gas produced a variety of objects, such as monomers, and other flammable hydrocarbons.

     The third stage of the process of ignition. When the second phase of the thermal degradation reaction to generate the concentration of fuel on fire to reach the limit, it should be with the oxygen in the atmosphere of each other.

     Second, the flame-retardant mechanism
     Plastic accession by a certain percentage of fire retardant, can increase the oxygen index, flame-retardant effect. Of course, the only index of oxygen and flammable materials that the flame retardants, should also adopt a series of parameters, such as the critical parameters of spontaneous combustion heat, heat energy light, heat, such as spontaneous combustion temperature. In general, contain flame retardants in the plastic burning, flame retardants in response to different regions (gas, together with *) various aspects of the work. For different materials, the role of the flame retardant may be different.
     The flame retardant mechanism is rather complicated. However, the aim is always to the physical and chemical means to cut off the combustion cycle. Flame retardants on the combustion reaction in the following areas:
     (1) Rally at compared with the endothermic decomposition of flame retardants, so that together with the relatively slow increase in temperature in order to slow down the decomposition temperature plastics, flame retardants use of thermal decomposition when it does not generate the Flammability of gas gasification Heat to reduce the temperature.
     (2) Flame retardant heat decomposition, the release of a captured combustion of ?OH (hydroxyl) radicals of the flame retardants, so that by free radical chain reaction for the combustion process to terminate the chain reaction.
     (3) in the role of heat, flame retardant heat-absorbing phase-change appears to prevent the pool phase of the temperature rise, so that the slow response to burn up to the stop.
     (4) With catalytic thermal decomposition, have a solid-phase product (coking layer) or foam layer, hinder the role of heat transfer. This together with the temperature maintained at a relatively low level, leading to gas as a raw material reaction (a product of decomposition of flammable gases) to reduce the speed of the formation.
     In short, the role of the flame retardants can be integrated to make the burning of the slow response or reaction so that the cause (spontaneous combustion heat) becomes difficult to achieve in order to curb and reduce fire hazards.