Polyformaldehyde development

Among the more than several uses for polyethers in ordn application is as a binder for extrusion-cast expls (Ref 3), and in a caseless proplht charge where the charge is used as an ammo element (Ref 5). Also, some development work on the use of Polyacetal resins (polyformaldehyde) as a fuel has been done by Singhal T ien y[Pg.816]

Aldehyde polymers are probably the oldest synthetic polymers [1—8]. Polyoxymethylene the polymer of formaldehyde, was first described by Butlerov in 1859 and the polymer of chloral was first prepared in 1832 by Liebig. This was about one century before the concept of linear macromolecules was developed. Polyformaldehyde and polychloral were isolated because they were stable at room temperature and above. 

Acetal polymers, also known as POM or polyacetal, are formaldehyde-based thermoplastics that have been commercially available since the 1960s. Polyformaldehyde is thermally unstable. It decomposes on heating to yield formaldehyde gas. Two methods of stabilizing polyformaldehyde for use as an engineering polymer were developed and introduced by DuPont, in 1959, and Celanese in 1962. 

The thermal destruction of polyformaldehyde with acetylated terminal groups was conducted on a circulation setup at a temperature of 300°C. Since the basic product of the thermal destruction of polyformaldehyde is monomeric formaldehyde, a successful performance of the analysis necessitated its separation from the other decomposition products, the amounts of which were two to three orders of magnitude smaller than the amount of the formaldehyde formed. For this a method was developed for separating formaldehyde, utilizing its property of spontaneous polymerization to Eu-polyoxymethylene at the temperature of... 

The Du Pont Company offered the first commercial acetal homopolymer, a high molecular weight polymer with a molecular structure of repeating carbon>oxygen links, under the trademark Delrln acetal resin In January 1960. The commercialization of Delrln followed 10 years of chemical research and development stimulated by work with pure monomeric formaldehyde and an Improved polyformaldehyde made by polymerization In a nonsolvent. 

In October 1956 a U.S. Patent was Issued to Du Pont on a high molecular weight, thermally stable polyformaldehyde (4). In an unusual move, Du Pont management decided in December 1956 to mount a large pre-commercial sales development effort, 2-1/2 years before the scheduled mid-1959 commercialization date. 

Polyacetals were among the first synthetic polymers studied by Staudinger in the 1920s. Polyformaldehydes prepared by both anionic polymerization of formaldehyde and cationic polymerization of TOX were, however, thermally unstable. Thus, they were not commercialized until the late 1950s when the reasons for the thermal instability were better imder-stood and the stabilization methods were developed. The DuPont process, based on anionic formaldehyde polymerization, involves esterification of unstable hemiacetal end groups from which degradation starts, while in the Celanese-Hoechst process TOX is copolymerized with a few percent of... 

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