Polymers, formaldehyde Paraformaldehyde

Both liquid and gaseous formaldehyde polymerize readily at low temperatures and can be kept in the pure monomeric state only for a limited time. Because of these facts, formaldehyde is sold and transferred either in solution or in polymerized form, such as paraformaldehyde and trioxane, described here under Formaldehyde polymers Commercial, 37% solution of formaldehyde (So-called Methanol-free)... 

Deflagration of Hydrazine Perchlorate-Additive Mixtures. Fuel Additives. In the case of ammonium perchlorate, it has been found (2) that at pressures below that at which pure ammonium perchlorate will sustain deflagration, ammonium perchlorate-fuel mixtures containing of the order of 5% fuel do deflagrate smoothly. Paraformaldehyde was the most effective fuel additive in promoting deflagration, and for that reason experiments were performed with mixtures of hydrazine perchlorate and various formaldehyde polymers. 

Experiments with paraformaldehyde were unsuccessful because it was found that when these additives were mixed with hydrazine perchlorate the mixture became yellow, and the consistency changed from that of the original powders to that of a dough. S-trioxane, a more stable formaldehyde polymer than paraformaldehyde, gave a less reactive mixture than paraformaldehyde, but the results were still unsatisfactory. Delrin, a stabilized formaldehyde polymer, proved even less reactive than S-trioxane. Magnesium oxide was added to hydrazine perchlorate-Delrin mixtures, on the theory that acidity in the hydrazine perchlorate might be... 

Formaldehyde vapors used in controlled-exposure inhalation studies can be generated by heating commercial formalin, aqueous solutions containing 30-50% formaldehyde by weight plus methanol or other substances to inhibit intrinsic polymerization, or by heating solid paraformaldehyde, a formaldehyde polymer. Unless noted otherwise, inhalation studies used in the preparation of this profile provided clear evidence that formaldehyde was the only added gas in the experimental atmosphere. 

Synonyms Eormaldehyde copolymer with urea Eormaldehyde/urea condensate Eormaldehyde/urea copolymer Eormaldehyde/urea polymer Eormaldehyde/urea precondensate Eormaldehyde/urea prepolymer Eormaldehyde/urea resin Formalin/urea copolymer Methylolurea resin Paraformaldehyde/urea polymer Paraformaldehyde/urea resin Polynoxylin Polyoxymethylene urea (INCI) UF Ure ormaldehyde adduct Urea/formaldehyde condensate Urea/formaldehyde copolymer Urea/formaldehyde oligomer Urea/formaldehyde polymer Urea/ formaldehyde precondensate Urea/formaldehyde prepolymer Urea, polymer with formaldehyde Classification Amino resin thermosetting resin Definition Thermosetting resin formed from condensation reaction of formaldehyde with urea formu/a (CH,N20 CH2O),... 

Formaldehyde, polymer with paraformaldehyde and phenol. See Phenol-formaldehyde resin Formaldehyde protechualdehyde-3,4-cyclic acetal. See Heliotropine... 

Paraformaldehyde, formaldehyde, phenol polymer Paraformaldehyde, phenol polymer. See Phenol-formaldehyde resin Paraformaldehyde/urea polymer Paraformaldehyde/urea resin. See Urea-formaldehyde resin... 

Synonyms Formaldehyde, phenol polymer Formaldehyde, polymer with paraformaldehyde and phenol Paraformaldehyde, formaldehyde, phenol polymer Paraformaldehyde, phenol polymer Phenol-formaldehyde copolymer Phenol, formaldehyde polymer Phenol, polymer with formaldehyde Phenol, polymer with paraformaldehyde Classification Thermosetting polymer Definition Reaction prod, of phenol with aq. 37-50% formaldehyde with basic catalyst chief class of phenolic resin Formula (CeHeO (CH20)x)x Properties Gray to bik., hard, infusible solid when cured resist, to moisture, soivs., heat to 200 C dimensionally stable good elec, resist. noncombustible... 

Synonyms P-F-R-2 resol phenol formaldehyde resin phenol formaldehyde phenol polymer with formaldehyde formaldehyde-pnenol polymer paraformaldehyde-formaldehyde-phenol polymer paraformaldehyde-phenol polymer phenol-formaldehyde polymer Novolac Resole resol based on phenol, resorcinol, and formaldehyde... 

Formulators can choose from a variety of commercially available phenolic compounds, including, in addition to phenol itself, the isomers of cresol, the isomers of xylenol, resorcinol, catechol, hydroquinone, bisphenol A, and various alkylphenols. Formaldehyde is usually used as the second major component, but acetaldehyde, furfuraldehyde, and paraformaldehyde (the polymer of... 

The most common grade of formaldehyde is known as formalin (37% formaldehyde). Polymer precipitation is usually inhibited by the addition of 7-15% methanol. The methanol does not interfere in resin production but is removed in the stripping operation. For economic reasons 44-50% uninhibited formaldehyde is used in commercial practice to save costs in stripping and to allow larger batch operations to be carried out. Occasionally paraformaldehyde is also used. The latter contains 91% formaldehyde and 9% water. 

Wattle tannin-based plywood adhesives were also crosslinked with 10% to 20% (by weight of solids) of either a phenol-formaldehyde resol or a phenol-resorcinol-formaldehyde polymer with approximately 20% resorcinol, to which paraformaldehyde was added to provide crosslinking between the resorcinol and... 

The reaction can continue to produce chains of polyoxymethylene glycol. To prevent precipitation of the formaldehyde polymer, known as paraformaldehyde, the solution can be stabilized by adding methyl alcohol. A 37% solution of formaldehyde must be maintained at a temperature of at least 32 C to prevent precipitation of the polymer. By adding 5-10% methanol, the solution will remain clear if stored at room temperature. 

Meth) i formate is also reported among the products obtained on heating formaldehyde polymers, such as paraformaldehyde, aloneand in the presence of sulfuric acid . 

Formaldehyde. Pure formaldehyde, CH2O, is a colorless, pungent smelling reactive gas (see Formaldehyde). The commercial product is handled either as soHd polymer, paraformaldehyde (13), or in aqueous or alcohoHc solutions. Marketed under the trade name Formcel, solutions in methanol, / -butanol, and isobutyl alcohol, made by Hoechst-Celanese, are widely used for making alcohol-modified urea and melamine resins for surface coatings and treating textiles. 

Paraformaldehyde [30525-89-4] is a mixture of polyoxymethylene glycols, H0(CH20) H, with n from 8 to as much as 100. It is commercially available as a powder (95%) and as flake (91%). The remainder is a mixture of water and methanol. Paraformaldehyde is an unstable polymer that easily regenerates formaldehyde in solution. Under alkaline conditions, the chains depolymerize from the ends, whereas in acid solution the chains are randomly cleaved (17). Paraformaldehyde is often used when the presence of a large amount of water should be avoided as in the preparation of alkylated amino resins for coatings. Formaldehyde may also exist in the form of the cycHc trimer trioxane [110-88-3]. This is a fairly stable compound that does not easily release formaldehyde, hence it is not used as a source of formaldehyde for making amino resins. 

Formaldehyde is a gas with a boiling point of -21 °C. It is usually supplied as a stabilised aqueous solution ( 40% formaldehyde) known as formalin. When formalin is used as the source of the aldehyde, impurities present generally include water, methanol, formic acid, methylal, methyl formate and carbon dioxide. The first three of these impurities interfere with polymerisation reactions and need to be removed as much as possible. In commercial polymerisation the low polymers trioxane and paraformaldehyde are convenient sources of formaldehyde since they can be obtained in a greater state of purity. 

When catalyzed by acids, low molecular weight aldehydes add to each other to give cyclic acetals, the most common product being the trimer. The cyclic trimer of formaldehyde is called trioxane, and that of acetaldehyde is known as paraldehyde. Under certain conditions, it is possible to get tetramers or dimers. Aldehydes can also polymerize to linear polymers, but here a small amount of water is required to form hemiacetal groups at the ends of the chains. The linear polymer formed from formaldehyde is called paraformaldehyde. Since trimers and polymers of aldehydes are acetals, they are stable to bases but can be hydrolyzed by acids. Because formaldehyde and acetaldehyde have low boiling points, it is often convenient to use them in the form of their trimers or polymers. 

Amino-substituted (Mannich base) polymers can be prepared by reacting amide-containing polymers with formaldehyde and a suitable amine. Sugiyama and Kamogawa (16) treated PAM in aqueous solution with excess paraformaldehyde (50°C, lh) followed by excess dimethylamine (50°C, lh). This procedure gave 68% conversion to amine. Schiller and Suen (9) used a similar procedure with monomeric formaldehyde and various amines, but with excess PAM. Muller et al. (17) prepared monomeric amines from... 

Paraformaldehyde, (CH20)n where n is between 8 and 100, is a convenient polymer of formaldehyde. The polymer is easily formed by removing water from a 50% formalin solution under reduced pressure. As the formaldehyde concentration increases, crystals of paraformaldehyde form spontaneously. It is available at 91-97% purity. It is more stable than neat formaldehyde but just as useful in applications, where it readily decomposes back to the straight stuff. 

The formaldehyde process is an air oxidation of methanol, CH3OH, which has water as a by-product. Formaldehyde is a gas at room temperature, but is usually handled either as a water solution called formalin or as polymers called paraformaldehyde and trioxane. Both are readily converted back ro formaldehyde. Some uses of formaldehyde are the manufacture of polymer resins and as a germicide. 

A number of expls have been prepd from raw materials involving formaldehyde. Although most of the formaldehyde expls are prepd from formaldehyde derivatives, several expls can be prepd directly in one operation from formaldehyde or anhydrous formaldehyde, or its polymer, paraformaldehyde. Walker (Ref 38), in his book on formaldehyde, gives a brief description of expls derived from it. For convenience, we divide them into two groups — those obtained directly from formaldehyde and those from formaldehyde derivatives... 

The polymer F of formaldehyde is called polyoxymethylene or paraformaldehyde. It contains two OH groups, one at each end of the molecule, but these are omitted for clarity in the structural formula shown in Figure 7.14. This shows that one molecule of water, which is present everywhere even in the most careful work, has been incorporated. If these terminal OH groups are functionalized, paraformaldehyde can be used as plastic. When paraformaldehyde is heated with acid, it is transformed (entropy gain) into the cyclic trimer B from Figure 7.14, which is called 1,3,5-trioxane. 

Formaldehyde and acetaldehyde are the most common aldehydes. Formaldehyde is a gas at room temperature, so it is often stored and used as a 40% aqueous solution called formalin. When dry formaldehyde is needed, it can be generated by heating one of its solid derivatives, usually trioxane or paraformaldehyde. Trioxane is a cyclic trimer, containing three formaldehyde units. Paraformaldehyde is a linear polymer,... 

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