China Factory Supply Paraformaldehyde in Stock

Paraformaldehyde

Chemical formula: OH(CH2O)nH (n = 8 - 100)

Appearance: white crystalline solid

Density: 1.42 g·cm−3 (25 °C)

Melting point: 120 °C (248 °F; 393 K)

Solubility in water: low

Paraformaldehyde (PFA) is a small polyoxymethylene polymer produced from formaldehyde. It has a typical degree of polymerization of 8-100 units and may have a slight formaldehyde odor. PFA is commonly used as a poly-acetal.

Synthesis

PFA forms slowly as a white precipitate in aqueous formaldehyde solutions, especially when stored in a cold environment. Formalin mostly consists of short chains of polyformaldehyde, with minimal monomeric formaldehyde. A small amount of methanol is often added as a stabilizer to control polymerization.

Reactions

Dry heating can depolymerize paraformaldehyde into formaldehyde gas, while water, a base, an acid, or heat can convert it into formaldehyde solution. The resulting high-purity formaldehyde solutions are used as fixatives in microscopy and histology.

Uses

Once depolymerized, formaldehyde derived from paraformaldehyde has diverse applications as a fumigant, disinfectant, fungicide, and fixative. Longer chain-length polyoxymethylenes, known as polyoxymethylene plastic (POM) or Delrin, are used as thermoplastics.

Paraformaldehyde can serve as a substitute for aqueous formaldehyde in the production of resinous binding materials. It is commonly used together with melamine, phenol, or other reactive agents for manufacturing particle boards, medium-density fiberboards, and plywood.