Polyether resins

(organic chemistry) Any member of a large group of thermoplastic or thermosetting polymers that contain the typical polyether linkages in the polymer chain.

Thermoplastic or thermosetting materials which contain ether-oxygen linkages, COC, in the polymer chain. Depending upon the nature of the reactants and reaction conditions, a large number of polyethers with a wide range of properties may be prepared. The main groups of polyethers in use are epoxy resins, phenoxy resins, polyethylene oxide and polypropylene oxide resins, polyoxymethylene, and polyphenylene oxides.

The epoxy resins form an important and versatile class of cross-linked polyethers characterized by excellent chemical resistance, adhesion to glass and metals, electrical insulating properties, and ease and precision of fabrication. Various fillers such as calcium carbonate, metal fibers and powders, and glass fibers are commonly used in epoxy formulations in order to improve such properties as the strength and resistance to abrasion and high temperatures. Some reactive plasticizers act as curing agents, become permanently bound to the epoxy groups, and are usually called flexibilizers. Rubbery polymers are added to improve toughness and impact strength. Epoxies are commonly used in protective coatings. They are used as potting or encapsulating compositions for the protection of delicate electronic assemblies from the thermal and mechanical shock of rocket flight, and as dies for stamping metal forms.

Polyethylene oxide and polypropylene oxide are thermoplastic products whose properties are greatly influenced by molecular weight. Low-to-moderate-molecular-weight polyethylene oxides vary in form from oils to waxlike solids. They are relatively nonvolatile, are soluble in a variety of solvents, and have found many uses as thickening agents, plasticizers, lubricants for textile fibers, and components of various sizing, coating, and cosmetic preparations. The polypropylene oxides of similar molecular weight have somewhat similar properties, but tend to be more oil-soluble (hydrophobic) and less water-soluble (hydrophilic). While polyalkylene oxides are not of interest as such in structural materials, polypropylene oxides are used extensively in the preparation of polyurethane foams.

Phenoxy resins are transparent, strong, ductile, and resistant to creep, and, in general, resemble polycarbonates in their behavior. The major application is as a component in protective coatings, especially in metal primers. See also Polyester resins.

Polyphenylene oxide (PPO) is the basis for an engineering plastic characterized by chemical, thermal, and dimensional stability. Polyphenylene oxide is outstanding in its resistance to water. Uses include medical instruments, pump parts, and insulation.

Polyoxymethylene, or polyacetal, resins are polymers of formaldehyde. Having high molecular weights and high degrees of crystallinity, they are strong and tough and are established in the general class of engineering thermoplastics. Polyacetals are typically resistant to fatigue, creep, organic chemicals (but not strong acids or bases), and have low coefficients of friction. Electrical properties are also good. The combination of properties has led to many uses such as plumbing fittings, pump and valve components, bearings and gears, computer hardware, automobile body parts, and appliance housings. See also Plastics processing; Polymerization.