Acetals poly

Gun Propellents. Low sensitivity gun propeUants, often referred to as LOVA (low vulnerabUity ammunition), use RDX or HMX as the principal energy components, and desensitizing binders such as ceUulose acetate butyrate or thermoplastic elastomers (TPE) including poly acetal—polyurethane block copolymers, polystyrene—polyacrjiate copolymers, and glycidyl azide polymers (GAP) to provide the required mechanical... 

Poly acetals are highly crystalline polymers. The number of repeating units ranges from 500 to 3,000. They are characterized by high impact resistance, strength, and a low friction coefficient. 

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 propint charge where the charge is used as an ammo element (Ref 5). Also, some development work on the use of Poly acetal resins (polyform aldehyde)1 as a fuel has been done by Singhal T ien yief 7)... 

The polymerization of the carbonyl group in aldehydes yields polymers, referred to as poly-acetals, since they contain the acetal repeating structure... 

Research Focus Synthesis of polycarbonates, poly(acetal carbonate)s, poly(spiroacetal)s, polyesters, and polyurethanes using dihydroxyacetone. 

Acetals, ketals, and their parent carbonyl compounds participate in this reaction [51]. Both simple and functionalized acetals undergo this reaction, as shown in Eq. (55) [173]. Double allylation was noted for the spiro-acetals with 2 equiv. allylsi-lane in the presence of TiCU (Eq. 56) [174,175]. Poly-acetals with the structure shown in Eq. (57) underwent clean production of a single product [176],... 

Since the acylated sugars are of such importance as intermediates in the syntheses of glycosides, constants for the poly-acetates and -benzoates have been collected in Tables VIII to X. Optical rotations are, again, usually given for solutions in chloroform. To the best of our knowledge, there is no recent compilation of constants for these compounds. For the other important class of intermediates in glycoside synthesis, the 0-acylglycosyl halides, the reader is referred to the Tables in a previous review in this Series. ... 

Table 9.2.1. Summary regarding reports in literature on the thermal decomposition of several poly (acetals).

As with other so-called engineering thermoplastics, the polyacetals are available modified with glass fibre, and may contain fire retardants, and some grades are blended with PTFE. In 1982 Hoechst introduced blends of poly acetals... 

It must, however, be stressed that for design purposes such data have little value. Like the nylons, which are also widely used for load-bearing light engineering applications, the poly acetals exhibit a small but finite creep under load. It is thus necessary to consider mechanical properties under those main headings. 

Fig. 8.7.3 Proton images (bottom) of a phantom made from poly (acetal) (Delrin) acquired with the time-suspension pulse sequence of Fig. 8.6.2, The field of view is (5.9 mm). The sample (top) has been imaged in three dimensions at 400 MHz with a voxel size of 92 x 92 x 625(pLtti). Adapted from [Corl2] with permission from Flsevier Science.

NONE-CONTROL TEST POLY ACETAL (DELRIN) NYLONS... 

In order to gain additional proof that ABA block copolymer has formed, degradation of the middle poly acetal block was attempted. This was done by heating a toluene solution of the polymer for 24 hrs at 60-80 °C in the presence of a catalytic amount (1 mol %) of triflic acid and subsequent evaporation of volatiles under vacuum ... 

Monomeric saccharides, nucleic bases, and amino acids are in general commercially available. The major synthetic problem with these natural compounds lies in the development of high-yield condensation reactions, which allow automated syntheses of poly(acetals) or polysaccharides, poly(phos-... 

The relatively advantageous properties of poly acetals have led to applications in a variety of markets, particularly as a replacement for metals, where it provides enhanced properties and lower costs. Table 15.10 shows areas and typical applications of polyacetals. 

Sulfone-hased polymers show a very good resistance to prolonged chlorine exposure at elevated temperatures. The weight change after an exposure of 6 months to static chlorinated water at 60°C at chlorine levels of up to 30 ppm is essentially zero for Udel , whereas e.g., poly(acetal) exhibits a weight loss of ca. 5% at 30 ppm chlorine in water after 6 months. This property suggests applications in water delivery systems. 

POM Poly (oxyme thy lene), poly formaldehyde, poly acetal... 

Structural components for bioprosthetic heart valves (poly(acetals)], artificial heart housings, catheter components, two-part systems for adhesives (e.g., epoxies)... 

---