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Effect of nano-flame retardant on oxygen index of WPC



As a new type of material, WPC material fully reflects the advantages of wood and plastic, and does not contain formaldehyde. It is widely used in outdoor building materials abroad. Since both thermoplastics and wood fibers are hydrocarbons, they are easily combustible in the presence of open flames or under heating. Therefore, WPC is a kind of flammable composite material, and it generates a lot of harmful gases during combustion, thus limiting Its scope of use, so it is often necessary to add flame retardant in the production process. Flame retardancy of wood-based composites involves flame retardancy of wood components and flame retardancy of polymers. Flame retardant of polyolefin and wood is often made of inorganic flame retardant (aluminum hydroxide, magnesium hydroxide, etc.), halogen-containing flame retardant (decabromodiphenyl ether, etc.) and phosphorus-containing flame retardant (ammonium phosphate, phosphate) Etc., etc., among which inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide are attracting attention because of their low price, excellent thermal stability, and the advantages of non-toxicity and smoke suppression.


experiment material

The shaving tree species are mainly Yunnan pine and eucalyptus, with an initial moisture content of 5.8%. High density polyethylene (HDPE) pellets with a density of 0.941 g/cm3 to 0.960 g/cm3. Industrial grade silane coupling agent. The decomposition temperature is 350 °C. Nano-aluminum hydroxide (nano-ATH) has a short-axis direction of 50-60 nm and a long-axis direction of 300-400 nm. Analysis of pure non-nano aluminum hydroxide (non-nano ATH).


equipment

Oxygen index tester

WPC preparation

The proportion of wpc wood is 6:4, and the amount of silane coupling agent is 2%. The plastic, shavings and coupling agent flame retardant are thoroughly mixed in the mixer according to the side, and manually laid into 305mmx350mm loose slab. Pre-pressing at room temperature (pre-pressure is IMPa, pre-stress is 30s) ), and then placed in an eight-plate vulcanizer for hot press forming. The nominal density of the plastic composite is set to 0.89/cm3 and the nominal thickness is 10xma. Main hot pressing parameters; hot pressing temperature 180 ° C. Hot pressing time 12rain, hot pressing pressure 2MPa.


Performance Testing

The oxygen index of wpc was tested according to GB/T2406-1993. The mechanical properties of plastic-wood composite wood were tested according to the Test Method for Physical and Chemical Properties of Artificial Panels and Finished Panels GB/T17657.1999.
Effect of Flame Retardant Types on WPc Oxygen Index

Figure 1 uses five flame retardants, where l represents nano MH, II represents nano ATH.III represents non-nano ATH, IV represents nano ATH+nm MH (ratio I: I). V represents nano ATn+ non-nano ATH (ratio 1:1), the amount of flame retardant is 12%.

Figure 1 shows the oxygen index of different flame retardant composite materials


It can be seen from Fig. 1 that the nano-flame retardant has better flame retardancy than the non-nano flame retardant; the nano MH and ATH are used separately, and the nano ATH is slightly better than the nano MH; the combination of nano MH and nano ATH can produce a synergistic effect; The combination of nano ATH and non-nano ATH produces an anti-synergy effect. This is because the nanoparticles have small particles and large specific surface area, plus the size effect and surface effect of the nanoparticles themselves. The contact area between the flame retardant and the matrix is increased, and the interaction and affinity between the flame retardant and the matrix interface is enhanced. To improve the compatibility of the two; the heat absorbed by MH and ATH is 1.42MJ/kg and 1.2 MJ/kg, respectively, and the thermal decomposition temperature of MH is high. Theoretically, the flame retardant effect of nano-MH should be better than that of nano ATH. Well, this experiment shows that nano ATH is slightly better than nano MH. This is because the two are not the same company products, although they are all nano-scale, but the size is still different, which affects its flame retardant effect.


equipment

Oxygen index tester

Plastic wood composite preparation

The proportion of wood-plastic composite wood is 6:4, and the amount of silane coupling agent is 2%. The plastic, shavings and coupling agent flame retardant are thoroughly mixed in the mixer according to the side, and manually laid into 305mmx350mm loose slab. Pre-pressing at room temperature (pre-pressure is IMPa, pre-stress is 30s) ), and then placed in an eight-plate vulcanizer for hot press forming. The nominal density of the plastic composite is set to 0.89/cm3 and the nominal thickness is 10xma. Main hot pressing parameters; hot pressing temperature 180 ° C. Hot pressing time 12rain, hot pressing pressure 2MPa.


Performance Testing

The oxygen index of plastic-wood composite wood was tested according to GB/T2406-1993. The mechanical properties of plastic-wood composite wood were tested according to the Test Method for Physical and Chemical Properties of Artificial Panels and Finished Panels GB/T17657.1999.
Effect of Flame Retardant Types on WPc Oxygen Index

Figure 1 uses five flame retardants, where l represents nano MH, II represents nano ATH.III represents non-nano ATH, IV represents nano ATH+nm MH (ratio I: I). V represents nano ATn+ non-nano ATH (ratio 1:1), the amount of flame retardant is 12%.

Figure 1 shows the oxygen index of different flame retardant composite materials

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