Composition Paraformaldehyde

Hydroxy-terminated polyester (HTPS) is made from diethylene glycol and adipic acid, and hydroxy-terminated polyether (HTPE) is made from propylene glycol. Hydroxy-terminated polyacetylene (HTPA) is synthesized from butynediol and paraformaldehyde and is characterized by acetylenic triple bonds. The terminal OH groups of these polymers are cured with isophorone diisocyanate. Table 4.3 shows the chemical properties of typical polymers and prepolymers used in composite propellants and explosives.E4 All of these polymers are inert, but, with the exception of HTPB, contain relatively high oxygen contents in their molecular structures. 

When paraformaldehyde is added to a solution of II in concentrated sulfuric acid at room temperature, a rapid reaction takes place, yielding colorless to orange polymeric compositions depending upon the ratio of reactants and the reaction condition employed (17). It is reasonable to assume that the polymerization of II with formaldehyde proceeds in a fashion similar to that of an activated aromatic ring with formaldehyde to yield as final products the diarylmethane and dimethylene oxy-derivatives, IV and V (Equation 9). 

RDX is used in most of the better explosives in service today, ranging from composition B, the standard bomb-filler used by the Air Force, to composition C-4, the best of the plastic explosives. The following process is the cheapest and easiest method I ve found for RDX production. It uses only three chemicals—ammonium nitrate, acetic anhydride, and paraformaldehyde. All three arc readily available, but procuring the acetic anhydride can be a bit touchy, however, as it is widely used in the production of the illegal thug methamphetamine, or "crystal," as it s called on the streets. 

The AN is mixed with the water first and heated to effect solution. With solution the Paraformaldehyde is added and the solution heated as in the first composition and boiled for one hour as above and vacuum dehydrated as above. 

Interest in pine bark as a source of adhesive components began to accelerate following the oil crisis of 1973. Sodium hydroxide extracts of southern pine bark were successfully used in replacing up to 40% of the phenolic resin for bonding of particleboards, oriented strandboards, and composites with a flakeboard core and veneer facing (50f51). Similar results were obtained with extracts from patula pine (52). Encouraged by results of this type, the New Zealand Forest Products Ltd. Corporation expanded their radiata pine bark tannin pilot plant to full-scale operation in 1981 to produce an extract trademarked Tannaphen. This material was crosslinked with paraformaldehyde and used as an adhesive... 

The reaction with azomethine yUdes is a typical [3+2]-cycloaddition. It leads to the products shown in Figure 3.74b. The reaction is particularly suitable to couple biologically active moieties to carbon nanotubes, which is of great relevance, for example, for the preparation of nanotube-peptide composites. The reaction is normally performed on a nano tube suspension in DMF that is treated with an N-substituted glycine and paraformaldehyde or with an aldehyde carrying a further residue to be coupled. The azomethine ylide is then formed in situ it constitutes the actual reagent. The method is appUcable to single- and multiwalled nanotubes. 

Natural CNSL itself (from solvent extraction), rich in anacardic acid has been initially reacted in aqueous systems in concentrated basic solution with paraformaldehyde and after addition of composite material has been heated and cured, during which process some decarboxylation of the anacardic acid polymer occurred, as shown in the scheme, to afford a particle board product (ref. 283) having excellent mechanical properties and resistance to water penetration. The customary use of organic solvents was avoided in this process. 

A multicomponent intramolecular condensation process was found to occur when o-phenylenediamine was reacted with paraformaldehyde and hydrogen sulfide to form a complex mixture of heteroatomic compounds, including l,2,4,5-tetrahydrobenzo[Reaction temperature and starting reagent ratio altered the yield and composition of the cyclothiomethylation produas. 

The synthetic route for the preparation of HCMSC capsules is as foUows. A total of 0.374 g of phenol was incorporated into the mesopores of 1.0 g of SCMS template by heating at 100°Cfor 12 hundervacuum. The resulting phenol-incorporated SCMS template was reacted with paraformaldehyde (0.238 g) under vacuum at 130°C for 24 h to yield a phenol resin/SCMS aluminosihcate composite. The composite was heated at 1 K/tnin to 160°C at which the temperatme was held for... 

The partial pressure of formaldehyde over paraformaldehyde is in reality the deeomposition pressure of the polyosymethylene glycols of which it is compoBed. Exact measurement of this pressure is extremely difficult, since rates of decomposition are slow and equilibrium conditions aie not readily attained. Variations in the composition of different samples of... 

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