Resin properties polyethers

The polyether-epoxy flexibilizers which contain epoxy groups along the chain (Scheme 57) impair better mechanical properties of the crosslinked composition in comparison with mixtures of aliphatic epoxy resins and polyether polyols. The improved properties are also obtained using 3,4-epoxycyclohexane-1-carboxylates of polyoxypropylene polyether polyols [38] (Scheme 58). 

Epoxy resins are polyethers prepared from glycols and dihalides and are extensively used as surface coatings, adhesives, and flexible enamel-like finishes because of their combined properties of toughness, chemical resistance, and flexibility. 

Properties molding resin, molding cellulose nitrate polyether reinforced filled... 

Foams prepared from phenol—formaldehyde and urea—formaldehyde resins are the only commercial foams that are significantly affected by water (22). Polyurethane foams exhibit a deterioration of properties when subjected to a combination of light, moisture, and heat aging polyester-based foam shows much less hydrolytic stabUity than polyether-based foam (50,199). 

Long-chain aUphatic acids such as adipic acid (qv) [124-04-9] are generally used to improve flexibiUty and enhance impact properties, demonstrating subtle improvements over resins modified with the ether glycols (diethylene glycol) and polyether glycols (polypropylene glycol) (see PoLYETHERs). 

Epoxy resins are really polyethers but are named epoxies because of the presence of epoxide groups in the starting material. They were initially synthesized from epichlorohydrin and bisphenol A in the 1940s. General properties are listed in Table 4.9. 

Polyethers 101 derived from 1 were mentioned in a patent describing the synthesis and properties of epoxy resins, and linear polyethers were prepared from free 1, which was reacted with a,co-bischloroalkanes or 1,6-dibromohexane [17]. 

Three different kinds of behavior were observed on addition of the polyethers to PVC and CPVC. First, high-impact resins were sometimes produced without the addition of any other rubber (3, 4). Second, incompatible mixtures with poor properties were obtained. Third, certain polyethers, which in themselves did not lead to PVC s of high impact strengths, seemed to enhance the properties of an already modified CPVC (5). 

Polyethers prepared by reaction with diepoxides have been described.79 Such reactions have been achieved from sucrose or partially esterified sucrose for the preparation of polymeric resins used as coating agents.78 Polysucrose (Ficoll400 ), a water-soluble copolymer prepared from sucrose and epichlor-hydrin, has been developed on the industrial scale. It is used as a biocompatible additive for cell separation and diagnostics, and is also described as having valuable properties as a food ingredient.18 Sucrose dicarboxylates can react with diamines to provide polyamides.183... 

Oligophenylethoxysiloxanes are used as modifiers for various polymers to improve their weather resistance and other technical characteristics, as well as to increase the heat resistance of coatings. E.g., PES-50 is used to modify polyethers, aciylic and epoxy polymers PES-80 is used to modify alkyd and urea-formaldehyde resins. Besides, PES-80 is used as an additive in paints and enamels (to improve their flow properties, gloss and colour), as well as in concrete mixes (to improve the water resistance and durability of concrete works). 

The above thermal analysis studies demonstrated the enhanced thermal stability of POSS materials, and suggested that there is potential to improve the flammability properties of polymers when compounded with these macromers. In a typical example of their application as flame retardants, a U.S. patent39 described the use of preceramic materials, namely, polycarbosilanes (PCS), polysilanes (PS), polysilsesquioxane (PSS) resins, and POSS (structures are shown in Figure 8.6) to improve the flammability properties of thermoplastic polymers such as, polypropylene and thermoplastic elastomers such as Kraton (polystyrene-polybutadiene-polystyrene, SBS) and Pebax (polyether block-polyamide copolymer). 

An alternative approach to using a rubber such as CTBN as the disperse phase is to use an engineering thermoplastic such as polyether sulfone or a polyimide in which the mechanical properties and Tg are more closely matched to those of the resin. These systems exhibit LCST behaviour, so the cure tempemture is located below the initial miscibility gap... 

Aromatic polyesters having an amorphous molecular structure. Compared with other amorphous engineering plastics in terms of heat resistance, polyarylates are generally positioned between polycarbonate on the low side and sulfone and polyether polymers on the high side. Compared with crystalline and semi-crystalline engineering plastics, polyarylate resins offer better resistance to warping, and generally comparable mechanical properties. 

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