Polymer polyfethylene terephthalate

The successful development of polyfethylene terephthalate) fibres such as Dacron and Terylene stimulated extensive research into other polymers containing p-phenylene groups in the main chain. This led to not only the now well-established polycarbonates (see Chapter 20) but also to a wide range of other materials. These include the aromatic polyamides (already considered in Chapter 18), the polyphenylene ethers, the polyphenylene sulphides, the polysulphones and a range of linear aromatic polyesters. 

With the expiry of the basic ICI patents on poly(ethylene terephthalate) there was considerable development in terephthalate polymers in the early 1970s. More than a dozen companies introduced poly(butylene terephthalate) as an engineering plastics material whilst a polyether-ester thermoplastic rubber was introduced by Du Pont as Hytrel. Polyfethylene terephthalate) was also the basis of the glass-filled engineering polymer (Rynite) introduced by Du Pont in the late 1970s. Towards the end of the 1970s poly(ethylene terephthalate) was used for the manufacture of biaxially oriented bottles for beer, colas and other carbonated drinks, and this application has since become of major importance. Similar processes are now used for making wide-neck Jars. 

Ashida, M., Composites of polychloroprene rubber with short fibres of polyfethylene terephthalate) and nylon, in Short Fiber-Polymer Composites, De, S.K. and White, J.R. (Eds.), Woodhead Publishing, Cambridge, 1996, Chapter 5. 

Both vibrational spectroscopies are valuable tools in the characterization of crystalline polymers. The degree of crystallinity is calculated from the ratio of isolated vibrational modes, specific to the crystalline regions, and a mode whose intensity is not influenced by degree of crystallinity and serves as internal standard. A significant number of studies have used both types of spectroscopy for quantitative crystallinity determination in the polyethylenes [38,74-82] and other semi-crystalline polymers such as polyfethylene terephthalate) [83-85], isotactic poly(propylene) [86,87], polyfaryl ether ether ketone) [88], polyftetra-fluoroethylene) [89,90] and bisphenol A polycarbonate [91]. 

Table 9. Mechanochemical polycondensation of polyfethylene terephthalate) with Polymer-...

Yeh JT, Hsieh SH, Cheng YC, Yang MJ, Chen KN. Combustion and smoke emission properties of polyfethylene terephthalate) filled with phosphorous and metallic oxides. Polym. Degrad. Stab. 1998 61 399 107. 

This distinction is primarily useful when the main chain of the macromolecule consists of carbon-carbon bonds. There is little point in labeling polyfethylene terephthalate), 1-5, a copolymer, since this repeating unit obviously contains the residues of two monomers and the polymer is made commercially only by reaction (1-1) or (1-7). Some polyesters are, however, made by substituting about 2 mol % of sodium-2,5-di(carboxymethyl) sulfonate (1-24) for the 3,5 isomer for the dimethyl terephthalate in reaction (1-7) ... 

The only practical means for ensuring the desired polymer quality is to use scrupulously pure monomers. Purification of a polymer after it is synthesized would be prohibitively expensive, because these materials are sparingly soluble and are often difficult or impossible to crystallize or free of solvent. The overall least expensive route to good quality polyfethylene terephthalate) was therefore through the dimethyl ester of terephthalic acid as shown in reaction (b). The byproduct methanol was recovered to generate more diester from the acid. In more recent years, methods have been developed to produce the diacid with satisfactory purity, and reaction (a) is now the preferred route to this polymer because the esterification step with methanol can be eliminated. Reactions (d), (e), and others, which the reader may be able to write, will be more expensive in the final analysis for the various reasons mentioned above. 

Suzuki F, Onozato K, and Takahashi N. Pervaporation of thermal mixture of benzene/toluene by polyfethylene terephthalate) membrane and synergetic effect on concentration dependence of diffusion rate. J Appl Polym Sci 1982 27 2179-2188. 

Figure 1.20 Spectra measured by raising the level of a polymer laminate sample consisting of a lOOpm-thick layer of polyfethylene terephthalate) (PET) under a 20pm-thick layer of poly(ethylene) (PE). The strongest bands in the Raman spectra of PE and PET are marked with arrows. Illustration courtesy of Dr Neil Everall, Measurement Science Croup, Intertek Corporation.

Crystallization can take place whenever the polymer is at a T above T. At 25° C, polycaprolactone is above Tg and so it may crystallize. On the other hand, polyfethylene terephthalate) can be quenched to 25°C at various rates resulting in various degrees of crystallinity which will not change as long as the temperature does not exceed Tg. So this polymer will be more suitable for the biodegradabOity study. 

Copolymers, Block Polymers, and Graft Polymers. When more than one monomer is involved, monomer-based names are more complex. Some common polymers have been given names based on an apparent structure, as with polyfethylene terephthalate) A better system has been approved by the lUPAC. With this method, the arrangement of the monomeric units is introduced through use of an italicized connective placed between the names of the monomers. For monomer names represented by A, B, and C, the various types of arrangements are shown in Table 1. 

Huang, B. and Walsch, J. J., Solid-phase polymerization mechanism of polyfethylene terephthalate) affected by gas flow and particle size. Polymer, 39, 6991-6999 (1998). 

Bech L, Elzein T, Meylheuc T, Ponche A, Brogly M, Lepoittevin B, et al. Atom transfer radical polymerization of styrene from different polyfethylene terephthalate) surfaces films, fibers and fabrics. Eur Polym J 2009 45(l) 246-55. 

In addition, the surface should be free of contaminating particles and occlusions that would interfere with the information retrieval process. A typical ablative-mode optical disk has the structure shown in Figme 16.14. The substrate is an optically transparent material such as polycarbonate, PMMA, polyfethylene terephthalate), or polyfvinyl chloride) topped by a subbing layer to provide an optically smooth surface for the recording layer. A metal reflector (typically aluminum) is then incorporated next to a transparent dielectric medium such as poly(a-methyl styrene) and, finally, the absorbing layer where the information pits are created is added. The latter can be a metal-polymer composite (silver particles in a gel) or a dye molecule dispersed in a polymer matrix such as squaryllium dyes, which act as infrared absorbers for GaAs lasers, typically... 

Reprinted with permission of Elsevier Science from Nobbs, J. H., Bower, D.I., Ward, I. M. and Patterson, D. A study of the orientation of fluorescent molecules incorporated in uniaxially oriented polyfethylene terephthalate) tapes . Polymer 15, 287-300. Copyright 1974. 

H. Li, Y. Ge, R Zhang, L. Wu, S. Chen, The effect of layer-by-layer chitosan-hyaluronic acid coating on graft-to-bone healing of a polyfethylene terephthalate) artificial Ugament, J. Biomater. Sci. Polym. Ed. 23 (2012) 425 38. 

Based on model reactions for the preparatiOTi of polyfethylene terephthalate) by ester interchange, the optimum molar ratio of ethylene glycol to dimethyl terephthalate is 2.4 to 1. This ratio allows complete removal of methanol [22]. The overall polyesterilication reaction is third order [22,23]. In addition, high molecular weight polymerizations of poly(ethylene terephthalate) invariably produce some cyclic oligomers as by-products [24, 25]. Eight different cyclic species were identified in (me commercial polymer ... 

Parashar, M.K., Gupta, R.P., Jain, A., and Agarwal, U.S. (1998) Reaction rate enhancement during swollen-state polymerization of polyfethylene terephthalate). /. Appl Polym. Sci., 67, 1589-1998. 

Bikiaris, D.N., Achilias, D.S., Giliopoulos, D., and Karayannidis, G.P. (2006) Effect of activated carbon black nanoparticles on solid state polymerization of polyfethylene terephthalate). Eur. Polym. /., 42, 3190-3201. 

Fakirov, S., Evstatiev, M., and Schultz, J.M. (1993) Microfibrillar reinforced composite fi om drawn polyfethylene terephthalate)/nylon-6 blend. Polymer,... 

Figure 5-4. X-Ray intensity as a function of Bra angle of amorphous (- - -) and crystalline (—polyfethylene terephthalate). The amorphous PETP was prepared by precipitation of the polymer from a solution in phenol-tetrachloroethane (1 1) with glycerol. Crystalline PETP was prepared by annealing (from A. Jeziorny and S. Kepka).

In 1972, Cottis and coworkers at Carborundum patented wholly aromatic polyesters based on p-hydroxybenzoic acid (HBA), A,A -dihydrox-ybiphenyl (DHB), and terephthalic acid (TPA), one of which was later commercialized as EKKCEL 1-2000 [1]. In 1974, Kuhfuss and coworkers at Eastman Kodak reported a new polyester based on HBA and polyfethylene terephthalate) (PET), which was later marketed under the code of X-7G. X-7G is the first thermotropic liquid crystalline polymer to be fabricated by injection molding or melt spinning [2]. However, then Eastman Kodak withdrew its plan of marketing of X-7G and changed the target with a wholly aromatic polyester commercialized as TITAN (THERMX ) in 1996. As described later, it was acquired by DuPont in 2003. 

In addition to the nucleating agents discussed in Section 18.4, many other materials have been found to be effective. Whilst the nylons may be self-nucleating, particularly if there is some unmelted crystal structure, seeding with higher melting point polymers can be effective. Thus nylon 66 and polyfethylene terephthalate) are reported to be especially attractive for nylon 6. 

Carolers also produced a number of aliphatic linear polyesters but these did not fulfil his requirements for a fibre-forming polymer which were eventually met by the polyamide, nylon 66. As a consequence the polyesters were discarded by Carothers. However, in 1941 Whinfield and Dickson working at the Calico Printers Association in England announced the discovery of a fibre from polyfethylene terephthalate). Prompted by the success of such a polymer, Faibenfabriken Bayer initiated a programme in search of other useful polymers containing aromatic rings in the main chain. Carbonic acid derivatives were reacted with many dihydroxy compounds and one of these, bis-phenol A, produced a polymer of immediate promise. 

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