Formaldehyde, combination with cellulose

Cellulose is insol in w, ale, eth all known simple org solvs. The best solv for it is cuprammonium hydroxide, [Cu(NH3)4(OH)2], also called Schweitzer s Reagent. It is also sol in a coned soln of Ca thiocyanate alone or in combination with formaldehyde. Other solvs gelatinizers for cellulose include zinc chloride (in 40% soln on heating), basic beryllium perchlorate, 84% phosphoric acid, selenic acid, arsenic acid, sulfurous acid, 66% HBr, 70-75% HF, coned HI, chloral with pyridine, chloral hydrate in H2S04, and inorg salts(such as NaCl) in coned solns at high temps. Coned solns of NaOH at ca -10° only partially dissolve cellulose while the remainder is swelled "mercerized . 

Folinerin, identity with oleandrin, I, 171 Forces of attraction between enzyme and substrate groupings, V, 56 Formaldehyde, combination with cellulose, V, 126... 

Celluloid combines synthetic and natural materials. Its successor, Bakelite, is originally completely synthetic, composed of carbolic acid mixed with formaldehyde. Later forms of bakelite also included cellulose fiber and natural pigments. 

The largest use is for binding fibrous and granulated wood into indoor composition board. Smaller uses are for wet-strength paper and permanent-crease textiles. About 4 percent of urea-formaldehyde resin is combined with alpha-cellulose to make molding powders (Table 15.18). These find use mainly in electrical parts such as switches, wall plates and receptacles, circuit breakers, electric blankets, handles and knobs. 

Ethyl cellulose cellulose nitrate in solution (or general-purpose household cement), epoxy, nitrile-phenolic, synthetic rubber or thermoplastic resin combined with thermosetting resin, and resorcinol-formaldehyde. 

Several mechanisms are needed to explain the action of the many different phosphorus compoimds used as FRs. Some of these compounds decompose in the condensed phase to form phosphoric acid or polyphosphoric acid. They can promote charring. Char formation is further enhanced by cellulosics, polyurethanes, phenolics, epoxy resins and EVA copolymers, and there are catalysts that promote it. Phenol-formaldehyde polymers can be used as flame retardants themselves when combined with a more flammable thermosetting polymer to form an interpenetrating network. 

Cellulose fibers in the form of papers and cotton had been used in combination with phenol-formaldehyde polymer as one of the earUest fiber-polymer composites [12]. Glass fibers later came on the scene and contributed to the commerciahzation of fiber-reinforced plastics [13]. The technical appHcations of fiber-reinforced plastic composites are shown in Figure 13.2. At least 50% of the fiber-reinforced plastics is used for automotive and construction applications. 

In the meantime another development had decisively altered the outset situation plastics had been discovered and synthesized, among them also some acid-stable ones such as phenol-formaldehyde resin or poly(vinyl chloride) (PVC). These opened up new possibilities cellulose papers could be impregnated with phenol-formaldehyde resin solution and thus rendered sufficiently acid-stable, and sintered sheets from PVC powder were developed. Independent separators producers were founded, combining knowledge of the chemical industry with experience of the battery industry and thus accelerating the development process. 

The advanced applications for nitrocellulose plastisol propellants require that they be integrally bonded to the motor case. Successful case bonding for the multiyear storage life of a rocket calls for special adhesives and liners which are completely compatible with these highly plasticized propellants. Best results have been obtained with a combination of an impervious rubber liner and a crosslinked adhesive system with a limited affinity for the plasticizers used in the propellants. Examples of effective liners are silica-filled butyl rubber and chlorinated synthetic rubber. Epoxy polyamides, isocyanate-crosslinked cellulose esters, and combinations of crosslinked phenol-formaldehyde and polyvinyl formal varnishes have proved to be effective adhesives between propellant and impervious liners. Pressure curing of the propellants helps... 

A particularly promising route is to treat the fiber with a phenolic resin based on cardanol formaldehyde (CF). This is a natural alkyl-phenol, in which the methylol groups are able to react with the hydroxyl groups of the cellulose, while the long C-15 alkyl group of cardanol facilitates the formation of an adhesive bond with non-polar TPs. It is concluded that Jute fiber thermoplastic RPs can bear comparison with glass fiber RPs. However, the best solution may well be a combination of treated jute with glass. 

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