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The application range of wood plastic composites is extremely wide, and some customers will doubt it. Will the application of wood plastic composite materials be limited by flame retardancy? Some customers think that the flame retardancy of wood plastic composites is not very good. The application of composite materials should not be so extensive. This view is obviously wrong.
How to test the flame retardancy of products used in wood plastic composite materials?
GB2408-80 horizontal combustion test method
The horizontal test method is to test the combustion performance of a sample under horizontal self-supporting under laboratory conditions.
GB2409-84 vertical combustion method
The vertical combustion method is a method of classifying the combustion of a vertically placed sample with a certain specification after flame action is applied under specified conditions.
GB2406-80 oxygen index test method
Oxygen Index (OI) —— Refers to the minimum oxygen content in the mixed gas required when the plastic is burned. The average concentration of oxygen in the air is 21%. Generally, an oxygen index below 21 is a flammable plastic, 22-27 is a self-extinguishing plastic, and a higher than 27 is a flame-retardant plastic. This method is relatively simple, with good digital reproducibility, and has the characteristics of using numbers to express the combustion performance of materials, so it is widely used abroad (for example, the American oxygen index test standard is ANST/ASTM D2863-1977). This method is not only applicable to self-supporting materials, but also applicable to films, foam plastics, etc.
GB8323-87 Smoke density test method
The test method is to determine the specific optical density of the material when it is irradiated or burned under the specified test conditions. The specific optical density is the specific optical density value calculated from the specified test chamber volume, optical path length, and the measured transmittance of the test area. The maximum optical density value is used to indicate the optical density of the material.
The purpose of flame retardant technology is to make non-flame retardant materials have flame retardant properties, which are not easy to burn or can self-extinguish under certain conditions.
Ways to flame-retardant products of wood plastic composites
1. The flame retardant carbonizes the combustible material to achieve the flame retardant effect. This flame retardant effect mainly plays a role in the solid phase. This type of flame retardant material is mainly phosphorus flame retardants (including organic phosphorus and inorganic phosphorus).
2. The flame retardant forms a non-volatile membrane under burning conditions to isolate the air to achieve the purpose of flame retardancy. This flame retardant effect mainly plays a role in the liquid phase. This type of flame retardant materials mainly include borate, halide, antimony oxide and phosphorus materials, or substances generated by the mutual reflection of these materials.
3. The decomposition product of flame retardant cuts off the chain reaction of hydroxyl radicals to achieve flame retardant. This flame retardant effect mainly plays a role in the gas phase. This type of material mainly plays a role in the gas phase. Such flame retardant materials are mainly halides and antimony oxide.
4. Dispersion of combustion heat and dilution of combustible substances. This kind of flame-retardant materials are mainly zinc borate, aluminum hydroxide, magnesium hydroxide and other substances, which are mainly due to the decomposition of a large amount of heat absorption, and the generated incombustible substances dilute the flammable gas to achieve the purpose of flame retardancy.
Generally, flame-retardant systems should try to use non-toxic, economical and synergistic flame-retardant materials. Commonly used flame retardant systems are: halogen-antimony oxide, phosphorus-nitrogen. However, the most commonly used flame retardant system is a mixture of selected flame retardant systems, which can ensure comprehensive flame retardant performance.
According to the above analysis, will the application of wood plastic composite materials be restricted by flame retardancy? I think everyone has the answer.
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