Polyacetals applications

It must, however, be stressed that for design purposes such data have little value. Like the nylons, which are also widely used for load-bearing light engineering applications, the polyacetals exhibit a small but finite creep under load. It is thus necessary to consider mechanical properties under those main headings. 

The polyacetals have a good record of performance in uses involving hot air and hot water. Plumbing components have been used for hot water service in the range 60-80°C and applications in hot air well in excess of 90°C. Recommended maximum continuous use temperatures are given in Table 19.4... 

In order to reduce the coefficient of friction in bearing applications small amounts of molybdenum disulphide are incorporated although in quantity this material may cause problems through acidic impurities. Blends of polyacetal and FIFE (20-25% P l FE) have a very low coefficient of friction (as low as 0.02)... 

Economic and ecological aspects of chemical recycling are examined, and the application of such processes to the recovery of monomers and intermediates from PETP, polyamides, polyurethanes, polycarbonates, unsaturated polyesters, polyacetals, PMMA and PS is discussed. 17 refs. SNIA... 

Polymers that are rigid at high temperatures are known as engineering plastics . This class of polymers includes polyacetal and many nylons. These polymers are used in applications such as small gears in office equipment and under the hood of automobiles. 

Essentially nonionic soil-release agents comprise polyesters, polyamides, polyurethanes, polyepoxides and polyacetals. These have been used mainly on polyester and polyester/ cellulosic fabrics, either crosslinked to effect insolubilisation (if necessary) or by surface adsorption at relatively low temperature. Polyester soil-release finishes have been most important, particularly for polyester fibres and their blends with cellulosic fibres. These finishes, however, have much lower relative molecular mass (1000 to 100 000) than polyester fibres and hence contain a greater proportion of hydrophilic hydroxy groups. They have been particularly useful for application in laundering processes. These essentially nonionic polymers may be given anionic character by copolymerising with, for example, the carboxylated polymers mentioned earlier these hybrid types are generally applied with durable press finishes. 

Poly(4-phenoxybenzoyl-1,4-phenylene) (PPBP), sulfonated, 23 718 Polyacetal, antioxidant applications, 3 121 Polyacetaldehyde, 1 103 Polyacetal fiber, 13 392 Polyacetylene, 7 514-515 26 953 conduction in, 7 527 22 208 molecular structure of, 22 211 optical band gap, 7 529t Peierls distortion in, 22 203, 208 room temperature conductivity, 7 532 synthesis of, 22 213... 

Other areas of application include a number of plastics which are processed at elevated temperature. P.R.209 lends color to polyolefins (in which it only slightly affects the shrinkage), to ABS, to polyacetal resins, and other industrial polymers. 

As can be deduced from plant purchases, the PRC is still at the formative stage where emphasis is on producing only the most basic petrochemicals. No plants were purchased for producing dibasic acids (phthalic and maleic anhydrides, etc.) and fluro-carbon or tetrafluoro ethylene or some of the advanced engineering plastics like ABS polyacetals, polycarbonates, polyimides or any other unsaturated polyesters. Another important area of low Chinese activity is thermoplastics for space and defense applications. ... 

Polyacetals and other engineering plastics cost about half that of cast metals, and are therefore used as replacements for cast metal-intense applications. They have been approved by the Food and Drug Administration for contact with foods. Some of the uses of molded polyacetals are as valves, faucets, bearings, appliance parts, springs, automotive window brackets, hose clamps, hinges, video cassettes, tea kettles, chains, flush toilet float arms, gears, shower heads, pipe fittings, pasta machines, desktop staplers, and air gun parts. 

Hsu D, Hoffman P, Mashburn (1972) Micro colorimetric method of dye staining and its application to cellulose polyacetate strip electrophoresis for the determination of acid glycosaminoglycans. Anal Biochem 46 156-163... 

Ethylene glycol in the presence of an acid catalyst readily reacts with aldehydes and ketones to form cyclic acetals and ketals (60). 1,3-Dioxolane [646-06-0] is the product of condensing formaldehyde and ethylene glycol. Applications for 1,3-dioxolane are as a solvent replacement for methylene chloride, 1,2-dichloroethane, 1,1,1-trichloroethane, and methyl ethyl ketone as a solvent for polymers as an inhibitor in 1,1,1-trichloroethane as a polymer or matrix interaction product for metal working and electroplating in lithium batteries and in the electronics industry (61). 1,3-Dioxolane can also be used in the formation of polyacetals, both for homopolymerization and as a comonomer with formaldehyde. Cyclic acetals and ketals are used as protecting groups for reaction-sensitive aldehydes and ketones in natural product synthesis and pharmaceuticals (62). 

Cationic polymerization of 1,3,5-trioxane provides one of a few examples of industrial application of cationic ring-opening polymerization. Polymerization leads to polyoxymethylene (polyformaldehyde, polyacetal), important engineering plastic. Polyformaldehyde may also be obtained by anionic polymerization of formaldehyde and this process is also used in industry. 

Among the more than several uses for polyethers in ordn application is as a binder for extrusion-cast expls (Ref 3), and in a caseless proplht charge where the charge is used as an ammo element (Ref 5). Also, some development work on the use of Polyacetal resins (polyformaldehyde) as a fuel has been done by Singhal T ien y[Pg.816]

Polymers containing ether groups in the backbone include two subclasses, namely true polyethers and polyacetals. Polyethers such as polyethylene glycol [-0-CH2-CH2-]n having higher polarity compared to polyhydrocarbons are used for many practical applications where some hydrophilic character is necessary. Epoxy resins are also polyethers. 

The most stable polyacetal polymer is polyformaldehyde (or polyoxymeth-ylene, POM) this is the only polyacetal that has reached commercial production. This resin has unique properties (e.g., selflubrication) and is very widely used in automotive applications such as engineering plastics. Acetals are widely used engineering thermoplastics with high load-bearing characteristics and low coefficients of friction. Currently, over 200 million lb of acetals are molded and extruded in the United States. 

---