Paraformaldehyde (PFA)
Paraformaldehyde (PFA) is the smallest polyoxymethylene, the polymerization product of formaldehyde with a typical degree of polymerization of 8–100 units. Paraformaldehyde commonly has a slight odor of formaldehyde due to decomposition. Paraformaldehyde is a poly-acetal.
Paraformaldehyde is the commercial linear polymer of formaldehyde. Paraformaldehyde is the mixture of low molecular weight of polyoxymethylene glycols. This polymer behaves chemically as a solid form of formaldehyde. It is much more stable and suitable both for storage and economical transportation.
Applications
Resins Industry:
The most important use of paraformaldehyde is as a source of formaldehyde groups in the production of many thermosetting resins, together with phenol, urea, melamine, resorcinol and other similar reagents. These resins are used as molding powders; in the wood industry as glues for chipboard, plywood and furniture; as bonding resins for brakes, abrasives and foundry dyes; as finishing resins for paper and textiles; as driers and glossing agents for paints; as insulating varnishes for electrical parts.
Disinfectant:
Paraformaldehyde generates formaldehyde gas when it is depolymerized by heating. The depolymerized material reacts with the moisture in the air to form formaldehyde gas. This process is used for the decontamination of large spaced and laminar-flow biological safety cabinets when maintenance work or filter changes require access to the sealed portion of the cabinet. It is used in the poultry industry as a disinfectant in the hatcheries, and cattle and sheep industry for sanitizing the bedding in the sheds. It releases formaldehyde gas when the temperatures increase. It reduces contamination levels caused by molds, viruses and bacteria.
Agriculture and Pesticides:
Most paraformaldehyde consumed by the agrochemicals industry is for the herbicides such as bismerthiazol, butachlor, acetochlor, glyphosate, and machete.
Embalming Process:
Formalin is used during embalming processes as a disinfectant and preservative. It is used as an injection fluid in arterial and cavity embalming, and in surface embalming as a fluid for soaking surface packs or a gel applied to the skin or internal surfaces. Paraformaldehyde, a powdered polymer form of formaldehyde, is also sometimes used in embalming processes.
Reagent for Organic Reactions:
In microbiology laboratories, fixation process (immunofluorescence) uses formalin 4% concentration. A blog by researchers mentioned that preparing this solution “fresh” from paraformaldehyde is better than using formalin that has been kept for some time. It is because more methylene glycol is present compared to its dimer and trimer oligomers and such solution of formalin 4% is absent of methanol.
Oil Well Drilling Chemicals:
Paraformaldehyde is used in the manufacturing of 1,3,5-triazine used as H2S scavenger in Oil drilling process.
