DuPont Delrin® POM

Table 3.10 Mechanical Properties at Various Temperatures of General Purpose Grades of DuPont Delrin POM [2]... 

Table 5.7 Coefficient of Friction of Several DuPont Delrin POM Plastics [2]...

DuPont Delrin P Nyltech Sniata POM Ticona Hostaform ... 

Figure 5.3 Flexural stress amplitude versus cycles to failure (ASTM D671) at various temperatures for DuPont Delrin 100, 500, and 900—unifilled POM [2].

Figure 5.5 Wear against mild steel in a thrust washer test for DuPont Delrin 500 and 500CL (internally lubri Gated) medium-viscosity POM resins (nonlubricated, P = 0.04 MPa, V = 0.95 m/s) [2].

Polycondensation of formaldehyde was reported by Buderov in 1859, but only in 1950 DuPont developed end-capping that prevented unzipping. POM is crystalline, thus rigid, brittle, and chemically non reactive. Production of Delrin , and Celcon started in 1959 and 1962, respectively. The world consumption of POM and its annual growth rate are 500 kton and 5%. 

Elastomer modihed POM compositions (Celcon from Celanese, Delrin , from DuPont, Duraloy ... 

Polyacetals are produced by reacting formaldehyde. These are also sometimes called polyoxymethylene (POM) and known widely as Delrin (DuPont). These polymers have a reasonably high molecular weight (>2 xlO g/mol) and have excellent mechanical properties. More importantly, they display an excellent resistance to most chemicals and to water over wide temperature ranges. 

A commercial grade of high-impact (notched Izod > 900 J/m) POM resin (Delrin 100 ST, DuPont) is believed to be a blend of POM with >30 wt% of a thermoplastic poly(ester-urethane) elastomer derived from poly(l, 4-butane adipate) diol and methylene-bis-(4,4 -diphenyl diisocyanate) (MDl) (Hexman 1989). This blend is reported to have a cocontinuous or semi-interpenetrating network of the elastomer in a matrix of the polyacetal (Flexman et al. 1990). The toughening effect in such a blend of IPN-type morphology was interpreted to occur partly through a rubber band mechanism by which the fracture energy is absorbed. The bands of rubbery domains were believed to span the crack and participate in the deformation process. 

Acetal polymers are formed from the polymerization of formaldehyde. They are also known by the name polyoxymethylenes (POM). Polymers prepared from formaldehyde were studied by Staudinger in the 1920s, but thermally stable materials were not introduced until the 1950s when DuPont developed Delrin. Homopolymers are prepared from very pure formaldehyde by anionic polymerization, as shown in Fig. 1.4. Amines and the soluble salts of alkali metals catalyze the reaction. The polymer formed is insoluble and is removed as the reaction proceeds. Thermal degradation of the acetal resin occurs by unzipping with the release of formaldhyde. The thermal stability of the polymer is increased by esterification of the hydroxyl ends with acetic anhydride. An alternative method to improve the thermal stability is copoly-... 

POM/TPU Delrin SOOT lOOST duPont Cams, gears, valves, plumbing... 

Polyoxymethylene (POM) Celcon Delrin Ticona Dupont Automotive fuel systems, E/E, plumbing, pump parts, appliances, electrical gears, zippers... 

POM is widely known as acetal and a well-known trade name is Delrin , manufactured by DuPont. This is a popular engineering plastic to replace parts that might otherwise be manufactured from metals. It is generally easy to machine and therefore makes for a good engineering plastic for small batch production or prototype applications. 

---