Polyethylene terephthalate groups

Friedrich et al. also used XPS to investigate the mechanisms responsible for adhesion between evaporated metal films and polymer substrates [28]. They suggested that the products formed at the metal/polymer interface were determined by redox reactions occurring between the metal and polymer. In particular, it was shown that carbonyl groups in polymers could react with chromium. Thus, a layer of chromium that was 0.4 nm in thickness decreased the carbonyl content on the surface of polyethylene terephthalate (PET) or polymethylmethacrylate (PMMA) by about 8% but decreased the carbonyl content on the surface of polycarbonate (PC) by 77%. The C(ls) and 0(ls) spectra of PC before and after evaporation of chromium onto the surface are shown in Fig. 22. Before evaporation of chromium, the C(ls) spectra consisted of two components near 284.6 eV that were assigned to carbon atoms in the benzene rings and in the methyl groups. Two additional... 

That fall, Carothers assistant Edgar W. Spanagel discovered polyethylene terephthalate, the polyester that Du Pont later manufactured under license as Dacron fiber and Mylar film. Carothers had made most of the polyesters, but he and others in his group assumed that Spanagel s polyester, like their earlier ones, melted at too low a temperature to be practical. As a result, Carothers did not have this one tested for spinnability. British scientists later used it to make Terylene. When Du Pont executives had to buy a license from the British to make Spanagel s fiber, their faces were bright red with embarrassment. 

Here the polymer grows by successive esterification with elimination of water and no termination step. Polymers formed by linking monomers with carboxylic acid groups and those that have alcohol groups are known as polyesters. Polymers of this type are widely used for the manufacture of artificial fibers. For example, the esterification of terephthalic acid with ethylene glycol produces polyethylene terephthalate. 

All of these intermolecular forces influence several properties of polymers. Dispersion forces contribute to the factors that result in increased viscosity as molecular weight increases. Crystalline domains arise in polyethylene because of dispersion forces. As you will learn later in the text, there are other things that influence both viscosity and crystallization, but intermolecular forces play an important role. In polar polymers, such as polymethylmethacrylate, polyethylene terephthalate and nylon 6, the presence of the polar groups influences crystallization. The polar groups increase the intensity of the interactions, thereby increasing the rate at which crystalline domains form and their thermal stability. Polar interactions increase the viscosity of such polymers compared to polymers of similar length and molecular weight that exhibit low levels of interaction. 

Oxidation is the first step for producing molecules with a very wide range of functional groups because oxygenated compounds are precursors to many other products. For example, alcohols may be converted to ethers, esters, alkenes, and, via nucleophilic substitution, to halogenated or amine products. Ketones and aldehydes may be used in condensation reactions to form new C-C double bonds, epoxides may be ring opened to form diols and polymers, and, finally, carboxylic acids are routinely converted to esters, amides, acid chlorides and acid anhydrides. Oxidation reactions are some of the largest scale industrial processes in synthetic chemistry, and the production of alcohols, ketones, aldehydes, epoxides and carboxylic acids is performed on a mammoth scale. For example, world production of ethylene oxide is estimated at 58 million tonnes, 2 million tonnes of adipic acid are made, mainly as a precursor in the synthesis of nylons, and 8 million tonnes of terephthalic acid are produced each year, mainly for the production of polyethylene terephthalate) [1]. 

Polymers having many flexibilizing groups (CH2, O), such as polyethylene. polyisoprene, and polysiloxanes (silicones), are flexible. Other less-flexible polymers may be flexibilized by the introduction of flexibilizing groups. For example, polybutylene terephthalate (PBT) is more flexible than polyethylene terephthalate (PET), and nylon 11 is less rigid than nylon 6. 

The detection of antimony species in drinking water stored in (polyethylene terephthalate) PET containers has been reported by several groups.38,39 As a result most commercially available PET materials typically contain 190-300 (xgg-1 Sb,40 whereby antimony trioxide is a suspected carcinogen. Sb that is leached from the PET containers in drinking waters was observed to be 100 times elevated compared with uncontaminated ground or drinking water... 

In addition to the established large volume products already mentioned, other plastic materials are known to be under study or have been introduced so recently that their markets have not been fully developed. It seems certain that products such as polyethylene terephthalate and polyacrylonitrile fibers will attain large volume production. A new type of resin that has appeared very recently is Shell Chemical Co. s Epon series (32), a group of polymers of various molecular weight ranges which are produced from phenol, acetone, and epichlorohydrin. 

The mechanochemical polycondensation reaction has been studied using heterochain polymer systems—polyethylene terephthalate poly-(e-caprolactam), cellulose, etc.—characterized by end groups that can be activated to increase their own number by mechanochemical destruction of corresponding polymers. The mechanochemical destruction was done in the presence of some suitable condensing agents, such as aliphatic and aromatic diamines and fatty acid dichlorides. 

Those containing end groups whose number can be increased by mechanochemical destruction—polyethylene terephthalate, poly (e-caprolactam), and cellulose. 

The most important representatives of this group are polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). The consumption of PET in the world (excluding fibers) was about 4x 106 t in 1997 (audio and video films, technical mouldings, packaging, particularly bottles). Even though the cost of these plastics is presently in the medium price range, one can count on a reduction in their price in the future due to their widespread use. 

As the next example, attention is directed to a polymer in which the end groups are not significant, namely the polymer which is commonly named as polyethylene terephthalate, abbreviated PET (Figure 5). IUPAC... 

Polyester A category of polymers that contain the ester functional group in their main chain. The most important polyester is polyethylene terephthalate... 

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