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Zinc borate concerted reaction with hydroxide Discussion

2013-09-16 by seoer8

Metal hydroxide flame retardants are HFR the main varieties , is one of the largest amount of the international community as a flame retardant , flame retardant accounted for about 4O% of the total , which mainly include hydrogen aluminum and magnesium hydroxide into two categories. Alone hydroxide as a flame retardant, after the filling too would flame retardant properties and physical properties have a huge impact , mainly through the particle surface modification and refinement to enhance flame retardant effect macromolecules taken to improve the bonding after filling the polymer mechanical properties. If the partial replacement of a hydrous oxide of zinc borate , zinc borate as promoting carbon and vitrification , and the synergistic effect of zinc borate , hydroxide , which can greatly reduce the material than smoky . And after adding ZnBO3 hydroxide can not only reduce the amount of the material properties can be improved , the mechanical performance loss is small. Zinc borate and hydrated alumina (ATH) for the EVA ( ethylene- vinyl acetate copolymer ) when the flame retardant system , zinc borate, aluminum oxide as a mineralizing agent and porous, rigid insulating glass layer ; while high temperatures with the release of water from the cooling , the heat absorbing action , EVA oxide liberated heat crack down 1277.04J / g. In the gas phase reacts with the gaseous halides of boron trihalides , boron trihalide hydrogen halide generated in the flame , thereby preventing the high Q of the chain reaction of free radicals and inhibit combustion gas addition , boron halide , zinc halide to dilute the combustible gas gases , to some extent reduces the combustion rate and thus achieve a flame process . l2. ] Zinc borate with Al (OH) 3 or Mg (OH) 2 mixture is filled into the EVA , that a synergistic effect of zinc borate . After this, the study of zinc borate in halogen-free flame retardant EVA, and were used to limiting oxygen index , UL - 94, cone calorimeter for different flame retardant system was tested and put forward the corresponding retardant mechanism . Mechanism that: thermal decomposition of aluminum hydroxide generated Alz0s protective film , not only blocking the entry of oxygen , but also to prevent the escape of flammable gases , delayed ignition time of EVA polymer , limiting polymer degradation . That the magnesium hydroxide flame retardant and zinc borate compound of the EVA layer is formed on the surface of glass , slowing the degradation of the polymer . For not adding zinc borate flame retardant polyethylene and adding zinc borate flame retardant polyethylene were physical properties, flammability test results showed that: no added zinc borate need to add a lot of magnesium hydroxide and hydrogen alumina complex system will have a retardant effect , but with the added amount of the increase , the physical properties and processing of polyethylene degradation ; while adding zinc borate , the limited oxygen burning time is reduced , the ignition time increased , with good smoke suppression performance , indicating zinc borate with Mg (OH) z, AI (OH). Have a good synergy , while zinc borate addition on the tensile properties was less affected.


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