Plastic to have flame retardant, flame retardant performance is good or bad specifically by what factors? Today, Jushi Chemical Editor will take you to understand the following:
First, filling.
Filling improves the thermal conductivity of the plastic, so that the internal temperature of the plastic increases, intensifying the decomposition of plastic and releasing more volatile combustible substances. Filler improves the viscosity of the plastic, reducing the heat carried away due to the flow of plastic and molten drops, especially 94ULV2-V1 grade products. The fillers gathered on the plastic surface form a barrier for mass and heat transfer, and some fillers also help to form a sintered surface layer and a carbon layer. Therefore, the filler can also increase the radiation heat loss from the combustion surface and heat transfer caused by conduction, and retard the flow of volatile products generated by the decomposition of plastics in the gas phase. Calcium carbonate, silica, glass fiber in plastic filler can affect the microstructure of the polymer, the formation of plastic nucleating agent, play a "wick effect", intensify combustion. Interference: For example, when the plastic containing silica powder burns, it will form a stable silicon bromide on the surface, which plays an interference role in the flame retardant plastic. Opposition effect: containing calcium carbonate and magnesium carbonate plastic to flame retardants have a confrontation effect, increasing the amount of plastic flame retardants used.
Second, the saturation of flame retardants.
The oxygen index of polyolefin to 30-32, fill with more phosphorus-based flame retardant masterbatch oxygen index will not increase without limit.
Third, the color masterbatch.
According to the understanding of Jushi Chemical, certain color powder will play a "wick role" in the plastic and promote the heat transfer of plastic. The additive of masterbatch contains calcium carbonate, magnesium carbonate and silica powder, which will play a serious interference role in flame retardant. Such as zinc stearate, zinc oxide will interfere with the formation of SbCl3 barrier layer on the surface of flame retardant plastics, playing a role in blocking.
Fourth, plastic.
The lower the melting index of the plastic resin itself, the more the amount of flame retardant will be. The higher the melt index, the less the amount of flame retardants. In PE plastic, the melting index is 0.5-1.0, and the amount of flame retardant is 5-10% more than the melting index of 4-7. Several kinds of plastic resins are mixed or because of processing equipment, resulting in poor local dispersion of flame retardant masterbatches in the polymer, which affects the flame retardancy. Recycled materials have different degrees of influence on flame retardancy due to the reduction of melting index and the inclusions of different varieties of plastics and fillers.