Poly oxymethylene Fibers

Polymeric additives for concrete have been described (52). These are fabricated from a poly(oxymethylene) (POM) copolymer. POM copolymers can be utilized to form fibrous additives for concrete, i.e., microfibers or macrofibers. The POM copolymers can also include chemical groups, e.g., end groups or pendant groups that can increase the polarity of the POM and thus increase the hydrophilic-ity of the formed fibers, which can improve miscibility of the fibers in wet concrete. The chemical groups of the POM copolymers can bond with components of the concrete or can hydrolyze to form groups that are bonding with some components of the concrete. 

A POM copolymer can be manufactured by the copol5merization of trioxane and a cyclic acetal. POM fibers can be formed from monomeric reactants as follows (52)  

Polymerization of trioxane with 1,3-dioxolane utilizing a BF3 initiator and a methylal chain transfer agent-designated POM. 

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Samon J M, Schultz J M, Hsiao B S, Khot S and Johnson H R (2001) Structure development during the melt spinning of poly(oxymethylene) fiber. Polymer 42 1547-1559. 

Fig. 4.169 Flexural-creep modulus of unreinforced and reinforced poly(oxymethylene) with 26 wt.-% of glass fibers at 20 and 80 °C [98Dom].

But other polymers such as it-poly(propylene) or poly(oxymethylene) can also be converted to what are known as hard-elastic fibers by suitable physical post-treatments (see also Section 38.3.1). At the present time, these energy elastic fibers are in the evaluation stage. 

Textile fibers (cotton, silk, wool, hair, rayon, nylon, polyester, aramid, etc.) Structural materials (lumber, composites, poly(oxymethylene), PVC, nylon, etc.) Rastios (polyethylene, polypropylene, polytetrafluoroethylene, polyoxide, etc.) Adhesives (glues, epoxies, polyvinyl alcohol, synthetic rubber, segmented polyurethanes, etc.) Biological materials (the basic molecules, carbohydrates, proteins, and DNA)... 

In this section the broad spectrum of melting of one-component macromolecular systems is described by means of several specific polymers. The description starts with polyethylene, the most analyzed polymer. It continues with two sections that present several special effects seen in the thermal analysis of polymers including some examples of detailed analyses by TMDSC, documenting the locally reversible melting and crystallization equilibrium within a globally metastable structure. Then illustrations of poly(oxymethylene) and PEEK are given as typical common polymeric materials. This is followed in the last section with the discussion of special effects seen in drawn polymers, as are commonly found in fibers and films. 

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