Function of Flame-Retardant Aluminum Hydroxide

The thermal dehydration and phase transition of flame-retardant aluminum hydroxide are highly complex.

The thermal dehydration and phase transition of flame-retardant aluminum hydroxide are highly complex. When aluminum hydroxide is used as a flame retardant, its quality indicators should be selected based on the thermal decomposition temperature of the polymer matrix material and the requirements of the molding processing temperature.

Modified flame-retardant aluminum hydroxide is one of the halogen-free flame retardants used in synthetic materials. Flame-retardant aluminum hydroxide possesses three major functions: flame retardancy, smoke suppression, and filling. It produces no secondary pollution during combustion. Not only does it exhibit excellent dispersibility in polymers, but it is also widely used in electrical appliances, wires, cables, daily necessities, building materials, transportation, and other plastic and rubber products.

Aluminum hydroxide used as a flame retardant in domestic and international markets is primarily aluminum trihydrate (ATH), typically represented as α-Al₂O₃·3H₂O. It appears as a crystalline or amorphous white powder. Its crystal structure comprises tightly packed base ions in an AB double-layer form, with aluminum ions stacked atop the 9s base ions. All resulting octahedral voids remain unfilled. Thus, the tightly packed meridian ions form a layered structure, and adjacent layers are connected by hydrogen bonds formed by the meridian ions.

 The thermal dehydration and phase transitions of aluminum hydroxide are highly complex. When used as a flame retardant, its quality specifications should be selected based on the thermal decomposition temperature and processing requirements of the polymer matrix material.

Flame-retardant aluminum hydroxide offers advantages including non-toxicity, excellent stability, and the absence of toxic gases at high temperatures. It reduces smoke and soot generation during plastic combustion and exhibits a low dehydration endothermic temperature. Flame-retardant polyolefins containing 60% aluminum hydroxide can serve as construction and interior decoration materials for automobiles and ships.

Flame-retardant aluminum hydroxide used domestically and internationally as a flame retardant is primarily aluminum hydroxide trihydrate (ATH), typically denoted as α-Al₂O₃·3H₂O. It exists as a crystalline or amorphous white powder. Its crystal structure comprises tightly packed base ions in an AB bilayer arrangement, with aluminum ions stacked atop the 9s base ions. All octahedral voids formed remain unfilled. Consequently, the tightly packed meridian ions constitute a layered structure, and adjacent layers are connected via hydrogen bonds formed by the meridian ions.