As a new type of material, plastic-wood composite material fully embodies the advantages of wood and plastic, and does not contain formaldehyde. It is widely used in outdoor construction materials in foreign countries. Because thermoplastic plastics and wood fiber are all hydrocarbons, the fire in the case of Or it is easy to burn in the case of heating, so WPC is a kind of flammable composite material, and it will produce a large amount of harmful gases during the combustion process, thus limiting the scope of its use, so it is often necessary to add flame retardants in the production process Flame-retardant of wood-plastic composites involves flame-retardation of wood components and flame-retardant to polymers. Inorganic flame retardants (aluminum hydroxide, magnesium hydroxide, etc.) are commonly used for the flame retardation of polyolefins and woods. Flame retardants (decabromodiphenyl ether, etc.) and phosphorus-containing flame retardants (ammonium polyphosphate, phosphate, etc.), among which inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide are inexpensive and have excellent thermal stability. , and has the advantages of non-toxic and smoke suppression and attention.
experiment material
The wood shavings species are mainly Yunnan pine and eucalyptus, with an initial moisture content of 5.8%. High-density polyethylene (HDPE) pellets, density 0.941g/cm3~0.960g/cm3. Industrial-grade silane coupling agent. Decomposition temperature 350°C. Aluminum hydroxide (nanometer ATH), 50-60nm in short axis direction, 300-400nm in long axis direction. Analytical pure non-nano-aluminum hydroxide (non-nano-ATH).
equipment
Oxygen index tester, plastic-wood composite material preparation.
The plastic-wood composite wood material has a ratio of 6:4, and the silane coupling agent is 2%. The plastic, shavings, and the coupling agent are mixed thoroughly in the mixer, and the hand lays 305mm x 350mm. Loose slab. Pre-pressing at room temperature (pre-pressing pressure is 1MPa, pre-pressing time 30s), and then put in eight-plate vulcanizing machine for hot-press molding. The nominal density of plastic composite is set to 0.89/cm3, Nominal thickness 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 materials was tested according to GB/T2406-1993. The mechanical properties of plastic-wood composite materials were tested in accordance with the test method for physical and chemical properties of artificial panels and decorative panels GB/T17657.1999.
Effect of flame retardant species 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+nano-MH (ratio 1:1), and V represents nano-ATn+non-nano-ATH (compared to inverted 1:1), flame retardant dosage is 12%.
Figure 1 Add oxygen index of different flame retardant recombination materials.
Figure 1 shows that: Nano-flame retardants have better flame-retardant properties than non-nano-flame retardants; nano-MH and ATH alone are slightly better than nano-MH; nano-MH and nano-ATH are used in combination to produce synergistic effects; The use of ATH and non-nano ATH hybrids produces anti-synergistic effects. This is due to the small nanoparticles, large specific surface area, plus the size and surface effects of the nanoparticles themselves. The contact area between the flame retardant and the matrix is increased. Enhance the interaction and affinity of flame retardant and matrix interface, improve the compatibility of the two; MH and ATH absorb the heat were 1.42MJ/kg, 1.2 MJ/kg, and the MH's thermal decomposition temperature is high, Theoretically, nano-MH should have better flame-retardant effect than Nano-ATH. However, this experiment shows that nano-ATH is slightly better than nano-MH. This is because both are not the same company's products. Although they are all nano-sized, they still have differences in size. , This affects its flame retardant effect.