Polyformaldehyde

polyformaldehyde

[‚päl·ē·fȯr′mal·də‚hīd]
(organic chemistry)

Polyformaldehyde

 

[—CH2O—]n, a linear polymer of formaldehyde; a white, horny crystalline substance with molecular weight 40,000–120,000, density 1.43 g/cm3 at 20°C, melting point 164°-180°C, and crystallinity 60–85 percent. Polyformaldehyde is one of the most rigid structural thermoplasts, with high mechanical strength and resistance to fatigue, wear, and moisture. It is used in a stressed state at temperatures from – 40” to 90°–20°C. Polyformaldehyde is resistant to nearly all neutral solvents and alkalies but decomposes under the action of mineral acids; it is flammable. Nonstabilized polyformaldehyde undergoes complete decomposition to formaldehyde upon heating to temperatures above 200°C. Polyformaldehyde is physiologically harmless.

Polyformaldehyde is produced industrially by polymerization of an anhydrous monomer or its cyclic trimer trioxane. During polyformaldehyde synthesis, 2–4 percent of a comonomer (for example, ethylene oxide or 1,3-dioxolane) is added to the reaction mixture to increase the thermostability of the product; other properties of these copolymers and polyformaldehyde are analogous. Polyformaldehyde is processed by injection molding and extrusion and is used mainly in the manufacture of various machine parts and, to a lesser extent, in fiber manufacture. It is produced under the trade names SFD and STD (USSR); Delrin, Celcon, and Polyfaid (USA); and Hostaform S (Federal Republic of Germany). World production of polyformaldehyde in 1972 was 120,000 tons.

REFERENCES

Enikolopian, N. S., and S. A. Vol’fson. Khimiia i tekhnologiia poliformal’degida. Moscow, 1968.
See also references under .

S. A. VOL’FSON

References in periodicals archive ?
Polyoxymethylene (POM) also known as polyacetal and polyformaldehyde is an engineering thermoplastic used in precision parts.
Small intestines, including the duodenum, jejunum and ileum, were immediately removed and cleaned using 0.01 M PBS, followed by fixing in a 4% polyformaldehyde solution for 24 h.
The smooth muscle cells were fixed using polyformaldehyde for 20 min, perforated using 1% Triton for 5 min, and blocked using 10% goat serum for 20 min, before being incubated at 4[degrees]C with anti-calponin antibody (GeneTex Inc., USA) overnight.[sup][35] Then, the cells were washed and incubated with fluorescence-conjugated secondary antibody by 1:50 dilution for 30 min under dark condition.
Primary microglia cells seeded on cover slips were fixed with 4% polyformaldehyde for 15 minutes and permeabilized with 0.2% Triton-X100 for 20 minutes at room temperature.
Kidneys and cells were fixed in 4% polyformaldehyde for 24 h and then embedded in paraffin, and 4 fm sections were cut.
Cells were fixed with 4% polyformaldehyde, permeabilized with 0.2% Triton X-100, and blocked with 3% BSA.
Specimens were fixed with 10% polyformaldehyde solution and prepared as paraffin sections and stained with hematoxylin and eosin (HE).
Wang, "Effects of magnesium hydroxide and its synergistic systems on the flame retardance of polyformaldehyde," Journal of Applied Polymer Science, vol.
After fixing with 4% polyformaldehyde, cells were incubated with anti-BrdU monoclonal antibody (Cell Signal, USA) at 4 [degrees]C overnight.
POM, also known as acetal, polyacetal and polyformaldehyde, is an engineering thermoplastic used in precision parts that require high stiffness, low friction and excellent dimensional stability.
Because of the lack of standardized nomenclature in our industry, these materials are often referred to as polyacetal (after the name of the original terminating group on the chain), polyformaldehyde (formaldehyde being the starting material for the polymerization), and polyoxymethylene (POM).
Cells were fixed with 4% polyformaldehyde for 15 min at 37 [degrees]C and rinsed three times with TBS containing 0.1% Triton X-100, and blocked with 5% nonfat milk for 1 h at room temperature.