Condensation polymers fibers

Oxamidoxime-terephthalic acid chloride-condensation polymer (fibers)... 

ETHYLENE We discussed ethylene production in an earlier boxed essay (Section 5 1) where it was pointed out that the output of the U S petrochemi cal industry exceeds 5 x 10 ° Ib/year Approximately 90% of this material is used for the preparation of four compounds (polyethylene ethylene oxide vinyl chloride and styrene) with polymerization to poly ethylene accounting for half the total Both vinyl chloride and styrene are polymerized to give poly(vinyl chloride) and polystyrene respectively (see Table 6 5) Ethylene oxide is a starting material for the preparation of ethylene glycol for use as an an tifreeze in automobile radiators and in the produc tion of polyester fibers (see the boxed essay Condensation Polymers Polyamides and Polyesters in Chapter 20)... 

Phosphorus-Containing Polymers. A large number of addition and condensation polymers having phosphoms built in have been described, but few have been commercialized (131,132). No general statement seems warranted regarding the efficacy of built-in vs additive phosphoms (133). However, in textile fibers, there is greater assurance of permanency. 

Aromatic Isocyanates. In North America, aromatic isocyanates ate heavily used as monomers for addition and condensation polymers. The principal appflcafions include both flexible and rigid polyurethane foam and nonceUulat appflcations, such as coatings, adhesives, elastomers, and fibers. 

In condensation polymers, the monomers are linked together by condensation reactions, like those used to form ester or amide links. Polymers formed by linking together monomers that have carboxylic acid groups with those that have alcohol groups are called polyesters. Polymers of this type are widely used to make artificial fibers. A typical polyester is Dacron, or Terylene, a polymer produced from the... 

As an example of a polyester fiber, consider the condensation polymer Dacron (also sold as a film—Mylar). The monomeric repeating unit of Dacron is shown in Fig. 7.8.2, with several linked monomers indicated in Fig. 7.8.3. While the... 

Condensation polymers tend to exist below their Tg at room temperature. They typically form fairly ordered structures with lots of strong interactions between the various chains giving strong materials with some, but not much, elongation when stretched. They are normally used as fibers and plastics. They have high stress/strain ratios. 

Condensation polymers include many of the materials referred to as synthetic or manmade fibers including polyesters (especially PET) and a variety of nylons (mainly nylon 6,6 and nylon 6). 

A number of plastics are condensation polymers and include polyesters and nylons that are not as highly oriented as the same materials but in fiber form. Other plastics have been developed that have outstanding heat stability, strength, and other properties that allow their wide use. These plastics include polycarbonates, polyimides, polybenzimidazoles, polysulfides, polyethers, polysulfones, and polyketones. 

Nature has long used reactions such as these to produce interesting solids such as cotton (seed pod), hemp (grass), and silk (cocoons for worms while they develop into moths) as fibers that we can strand into rope or weave into cloth. Chemists discovered in the early twentieth century that cellulose could be hydrolyzed with acetic acid to form cellulose acetate and then repolymerized into Rayon, which has properties similar to cotton. They then searched for manmade monomers with which to tailor properties as replacements for rope and sdk. In the 1930s chemists at DuPont and at ICl found that polyamides and polyesters had properties that could replace each of these. [Linear polyolefins do not seem to form in nature as do condensation polymers. This is probably because the organometaUic catalysts are extremely sensitive to traces of H2O, CO, and other contaminants. This is an example where we can create materials in the laboratory that are not found in nature.]... 

Thermal and Oxidative Stability. In general, polyolefins undergo thermal transitions at much lower temperatures than condensation polymers thus, the thermal and oxidative stability of polyolefin fibers are comparatively poor. Preferred stabilizers are highly substituted phenols such as Cyanox 1790 and lrganox 1010, or phosphites such as Ultranox 626 and Irgafos 168. 

The advantage of these polymers over poly(vinylferrocenes) or related species with pendent organometallic units is that the condensation polymers have ferrocene units in the main chain where they can exert their maximum influence on polymer thermal stability. The disadvantage of the condensation products is that, except in the last example, the molecular weights are too low to favor fiber or flexible film formation. Nevertheless, this work indicated the potential usefulness of polymers with metallocene units in the main chain. 

Poly-2-2 -(w-phenylene)-5,5 -bibenzimidazole, commonly called polybenzimidazole (PBI), was developed under the aegis of the U.S. Air Force Materials Laboratory in cooperation with the then-existing Celanese Corporation. The fiber went into commercial production in the United States in 1983. It is a condensation polymer obtained from the reaction of tetra-aminobiphenyl and diphenylisophthalate in a nitrogen atmosphere at temperatures that may reach 400°C in the final stages.29 The structure of a repeating unit is shown below. 

Hercules Kymene 557 is the cationic, water-soluble, wet strength resin, which conservators know because of its use in the manufacture of calcium carbonate filled P/D paper. In its synthesis, a condensation polymer of adipic acid and diethylene triamine is reacted with epichloro-hydrin to introduce reactive epoxy groups. The behavior of Kymene in dispersed fiber has been investigated by Bates (6,7). 

Like nylon, polyester fibers are made from linear-condensation polymers by melt spinning, followed by drawing. Similar to nylon, the drawing treatment involves a stretch ratio of 5. The drawing of polyester fiber is done above its glass transition temperature of 80°C. 

Properties of fibers can be altered by carrying out interfacial polymerizations on their surfaces. Thus the shrink resistance of wool can be improved by immersing the fiber first in a solution containing one component of a condensation polymer and then immersing it in another solution containing theother component. Polyamides, polyurethanes, polyureas, and other polymers and copolymers may be grafted on wool in this manner. 

One of the most important condensation polymers is nylon, a name so ingrained into our language that it has lost trademark status. It was developed by Wallace Carothers, director of organic chemicals research at DuPont, and was the outgrowth of his fundamental research into polymer chemistry. Introduced in 1938, it was the first totally synthetic fiber. The most common form of nylon is the polyamide formed by the condensation of hexamethylene diamine and adipic acid ... 

The condensation polymer made by reacting ethylene glycol with 1,4-benzene dicarboxylic acid (terephthalic acid) produces a polymer that is almost exclusively converted into the fiber Dacron. The polymerization is run as an ester interchange reaction using the methyl ester of terephthalic acid ... 

---