Acrylic acid, stabilized hly

Physical Properties

• Appearance: Colorless, clear liquid.
• Odor: Characteristic pungent, acrid, and irritating odor.
• Melting Point: Approximately 13–15 °C (it can easily solidify at room temperature in cold environments).
• Boiling Point: Around 141 °C.
• Density: ~1.05 g/cm³ at 20 °C (slightly heavier than water).
• Solubility: Highly miscible with water, ethanol, ether, and most common organic solvents.
• Flash Point: Approximately 54 °C, making it a combustible liquid. Its vapors can form explosive mixtures with air.

Chemical Properties

• Highly Reactive Polymerization: This is its most critical property. The molecule contains a highly reactive carbon-carbon double bond, causing it to readily undergo free-radical polymerization when exposed to heat, light, or peroxides. Commercial products always contain polymerization inhibitors (like MEHQ) to prevent premature self-polymerization during storage and transport.
• Acidity: It is a weak carboxylic acid but is highly corrosive. Aqueous solutions are strongly acidic and can cause severe skin burns and permanent eye damage.
• Reactivity: In addition to polymerization, the double bond allows it to participate in addition reactions, while the carboxyl group enables esterification, amidation, and neutralization reactions.
• Incompatibility: Highly incompatible with strong oxidizing agents, strong bases, amines, and reducing agents. Contact with these materials can trigger violent exothermic reactions.

Key Applications

• Superabsorbent Polymers (SAPs): This is one of its largest applications. Neutralized acrylic acid is polymerized to create SAPs, which are widely used in disposable diapers, feminine hygiene products, and adult incontinence pads due to their ability to absorb hundreds of times their weight in water.
• Acrylic Polymers & Resins: Used extensively to produce polyacrylic acid and copolymers. These are essential in water-based architectural paints, textile coatings, adhesives, sealants, and paper treatment.
• Ester Derivatives: Reacted with alcohols to produce acrylate esters (such as methyl acrylate, ethyl acrylate, and butyl acrylate), which serve as fundamental monomers for manufacturing plastics, rubbers, and synthetic fibers.
• Water Treatment & Scale Inhibitors: Low-molecular-weight polyacrylic acid acts as an excellent dispersant and scale inhibitor in industrial cooling water systems and boiler water treatment.
• Personal Care Products: Carbomers (cross-linked polyacrylic acids) are heavily used as thickening agents, emulsion stabilizers, and suspending agents in cosmetics, lotions, and hair gels.