Ammonium Polyphosphate (APP)

Ammonium Polyphosphate (APP) - CAS.68333-79-9

Ammonium Polyphosphate (APP) is an inorganic salt of polyphosphoric acid and ammonia. It exists as both a crystalline solid and an amorphous, glassy substance. Its properties and applications vary significantly depending on its degree of polymerization (chain length), which is categorized as short-chain (or crystalline) APP and long-chain (or amorphous) APP.it widly to be used in flame retardant and fertilizer industry.

1. Chemical Structure and Properties

CAS: 68333-79-9

Appearance: White, free-flowing powder or granules.

Solubility: Short-chain APP (n < 100): Water-soluble. This form is used primarily in fertilizers，Long-chain APP (n > 1000): Water-insoluble. This is the key form used in flame retardants.

Decomposition: Upon heating, APP decomposes, releasing ammonia (NH₃) and forming polyphosphoric acid. This endothermic reaction and the formation of a protective char layer are central to its function as a flame retardant.

2. Primary Applications

A. Flame Retardants (Most Significant Application)

Long-chain,water-insoluble APP is a leading intumescent flame retardant.it is non-halogenated, which makes it an environmentally preferred choice over brominated flame retardants.

Mechanism of Action (Intumescence):

1. Heat Sink (Endothermic Decomposition): When exposed to fire, APP decomposes, absorbing heat and cooling the material.

2. Formation of Protective Char: The decomposition products catalyze the dehydration of carbon-rich compounds (e.g., polymers or added carbon sources like pentaerythritol). This creates a swollen, multicellular, carbonaceous layer ("char") on the surface.

3. Barrier Formation: This char layer acts as a physical barrier, insulating the underlying material from heat and oxygen and blocking the release of flammable gases.

Common Uses:

Polyolefins:PP (polypropylene), PE (polyethylene) for cables, pipes, and construction materials.

Coatings and Paints: Intumescent fire-resistant coatings for structural steel, wood, and fabrics.

Epoxy Resins and Polyurethanes: Used in electronics, adhesives, and composites.

Rubber Products.

Key Advantages as a Flame Retardant

Halogen-Free: Does not produce corrosive or toxic dioxins and furans during combustion.

Low Toxicity: Safer to handle compared to many alternative flame retardants.

Efficiency: Effective at relatively low loadings in polymer formulations.

Synergistic:Works very well in combination with other agents like melamine and pentaerythritol (forming the classic "intumescent system").

B. Fertilizers

Short-chain, water-soluble APP is an excellent source of two essential plant nutrients: nitrogen (N) and phosphorus (P). It is often used in liquid fertilizer formulations and is a key component in NPK fertilizers.

Advantages:

High water solubility allows for easy uptake by plants.

Low salt-out temperature, making it suitable for liquid blends with other nutrients like potassium and micronutrients.

3. Safety

Handling: Use with adequate ventilation. Wear appropriate protective equipment (safety glasses, dust mask, gloves) to minimize dust inhalation and contact with eyes and skin.

Storage: Store in a cool, dry, well-ventilated place in a tightly closed container.

Product technical consultation: E-mail:Sales@hxochem.com Whatsapp: +8613330004268, WeChat: +8613285168509