Terephthalate/naphthalate

The copolymers are prepared using a mixture of dimethyl terephthalate and dimethyl naphthalate. Published data indicates a reasonably linear relationship between and copolymer composition on the lines discussed in Section 4.2, e.g. Tg for a 50 50 copolymer is about 100°C which is about mid-way between Tg figures for the two homopolymers. In line with most other copolymers there is no such linearity in the crystalline melting point (T, ). As comonomer levels are introduced drops from the values for both homopolymers and indeed crystallisation only readily occurs where one of the components is dominant, i.e. 80%. Thus commercial copolymers are usually classified into two types ... 

The semicrystalline polyesters of the terephthalate and naphthalate family are resistant to a wide range of chemicals at room temperature, including water, alcohols, ketones, ethers, glycols, chlorinated solvents, aliphatic hydrocarbons, and oils. They are slowly hydrolyzed in boiling water and rapidly degraded in strongly basic or acidic medium. 

TABLE 2.12 Physical Properties of Poly(ethylene terephthalate) (PET) and Polyethylene 2,6-naphthalate) (PEN) Polyester Fibers... 

Ethanedioic (oxalic) Propanedioic (malonic) Butanedioic (succinic) Pentanedioic (glutaric) Hexanedioic (adipic) Heptanedioic (pimelic) Octanedioic (suberic) Nonanedioic (azalic) Decanedioic (sebacic) Undecanedioic Dodecanedioic Phthalic Isophthalic Terephthalic 1,4-Naphthalic... 

Shi, Y. and Jabarin, S. A., Transesterification reaction kinetics of poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) blends, J. Appl. Polym. Sci., 80, 2422-2436 (2001). 

The influence of the ratio of hydroxylic/carboxylic end groups has been studied by several research groups. In the case of PET, this varies, based on the assumed mechanism over the range of 1.5-4.5 1. For poly(butylene terephthalate) (PBT) and polyethylene naphthalate) (PEN), the optimum is indicated at 2.0 1 [19, 20]. Any deviation from this ratio affects the reaction rate. 

The above-mentioned results of the SSP of PET can be generally applied to other semicrystalline polyesters, such as poly(butylene terephthalate) (PBT), poly(tri-methylene terephthalate) PTT), polyethylene naphthalate) (PEN) or any other kind of semicrystalline co-polyester, as a result of their similar reaction behaviors. Most of the studies have been focused on PET and PBT due to their industrial importance. Meanwhile, the popularity of PEN is growing on account of the outstanding properties of this particular polymer. 

Although the superior properties of PEN have been known for many years, the unavailability of the naphthalate monomer has delayed the development of commercial markets, until relatively recently (1995) when the Amoco Chemical Company offered high purity naphthalene-2,6-dimethyl dicarboxylate (NDC) in amounts of up to 60 million pounds per year. This diester is produced by a five-step synthetic route, starting from the readily available compounds, o-xylene and 1,4-butadiene [3], Prior to this, the NDC diester was obtained by extraction of 2,6-dimethylnaphthalene (DMN) from petroleum streams, where it was present in relatively low abundance. Oxidation of DMN to crude 2,6-naphthalene dixcarboxylic (NDA) is conducted by a similar process to that used for conversion of p-xylcnc to purified terephthalic acid (TA), crude NDA is esterified with methanol, and is then distilled to yield high purity NDC. Other companies (e.g. the Mitsubishi Gas Chemical Company) followed Amoco s introduction with lesser amounts of NDC. Teijin [4] has manufactured PEN for many years for its own captive uses in films. 

Chuah et al. [107] prepared a series of PTT/poly(trimethylene napthalate) (PTN) copolyesters by copolymerizing PDO with dimethyl terephthalate and dimethyl naphthalate. The PTN homopolymer has a 7 g of 75 °C and a Tm of 245 °C. Despite the more rigid napthalate moiety, the PTN Tg and Tm were much lower than the Tg of poly(ethylene naphthalate) (PEN), indicating the strong influence of the flexible trimethylene units. 

It should be taken into account that all of the aspects described above are of a general nature and therefore more or less valid for any kind of industrially relevant polyester resin. Upon closer examination, the experiences gained with PET are particularly applicable to poly(butylene terephthalate) (PBT), poly(trimethylene terephthalate) (PTT) and polyethylene naphthalate) (PEN). These polymers have gained major industrial importance as a result of a number of different properties in comparison with PET. 

While depolymerizing poly(ethylene naphthalate) could be attractive on the small scale because of the high commercial price for the naphthalate moiety, even this candidate resin is in too little availability to permit economical depolymerization. Of polyesters, only poly(ethylene terephthalate) (PET) is available at sufficient quantities to make the commercial use of depolymerization potentially attractive. 

It should additionally be noted that a number of the paths of the schemes above have received some confirmation in a number of literature reports dealing with the photolysis and photo-oxidation of other polyesters [32-35], Because these reports investigated poly(butylene terephthalate) (PBT), poly(ethylene naphthalate) and poly(butylene naphthalate), however, they may not have direct application to understanding of the processes involved in PET and PECT and so have not been discussed in this present chapter. All do contain support for the formation of radicals leading to CO and C02 evolution, as well as the hydrogen abstraction at glycolic carbons to form hydroperoxides which then decompose to form alkoxy radicals and the hydroxyl radical. These species then were postulated to undergo further reaction consistent with what we have proposed above. 

The ratio min represents the molar ratio of cl-HQ/BB (m) to added modifier, e.g. terephthalic acid (TA) and 2,6-naphthalic dicarboxylic acid (NDA), ( ). 

MC MDI MEKP MF MMA MPEG MPF NBR NDI NR OPET OPP OSA PA PAEK PAI PAN PB PBAN PBI PBN PBS PBT PC PCD PCT PCTFE PE PEC PEG PEI PEK PEN PES PET PF PFA PI PIBI PMDI PMMA PMP PO PP PPA PPC PPO PPS PPSU Methyl cellulose Methylene diphenylene diisocyanate Methyl ethyl ketone peroxide Melamine formaldehyde Methyl methacrylate Polyethylene glycol monomethyl ether Melamine-phenol-formaldehyde Nitrile butyl rubber Naphthalene diisocyanate Natural rubber Oriented polyethylene terephthalate Oriented polypropylene Olefin-modified styrene-acrylonitrile Polyamide Poly(aryl ether-ketone) Poly(amide-imide) Polyacrylonitrile Polybutylene Poly(butadiene-acrylonitrile) Polybenzimidazole Polybutylene naphthalate Poly(butadiene-styrene) Poly(butylene terephthalate) Polycarbonate Polycarbodiimide Poly(cyclohexylene-dimethylene terephthalate) Polychlorotrifluoroethylene Polyethylene Chlorinated polyethylene Poly(ethylene glycol) Poly(ether-imide) Poly(ether-ketone) Polyethylene naphthalate Polyether sulfone Polyethylene terephthalate Phenol-formaldehyde copolymer Perfluoroalkoxy resin Polyimide Poly(isobutylene), Butyl rubber Polymeric methylene diphenylene diisocyanate Poly(methyl methacrylate) Poly(methylpentene) Polyolefins Polypropylene Polyphthalamide Chlorinated polypropylene Poly(phenylene oxide) Poly(phenylene sulfide) Poly(phenylene sulfone)... 

Poly(ethylene terephthalate) (PET), eg. DuPont Teijin Films Melinex polyester film, and poly(ethylene naphthalate) (PEN), eg. DuPont Teijin Films Teonex polyester film, are biaxially oriented semicrystalline films [1], The chemical structures of PET and PEN are shown in Fig. 7.1. 

This deficiency is overcome by application of a hard coat to the amorphous resins this substantially improves resistance to the solvents and chemicals such as NMP, IPA, acetone, methanol, THF, ethyl acetate, 98% sulfuric acid, glacial acetic acid, 30% hydrogen peroxide, and saturated bases such as sodium hydroxide [13]. With poly(ethylene terephthalate) and of poly(ethylene naphthalate) films a hard coat is not required for solvent resistance. 

One of the main drivers in moving to plastic substrates is that it opens up the possibility of roll-to-roll processing and the process and economic advantages that this brings. Under these conditions a winding tension will clearly be present and polymer film substrates with low moduli will be susceptible to internal deformation, particularly at elevated process temperatures. Figure 7.8 shows a comparison between poly(ethylene terephthalate) and poly(ethylene naphthalate) films. 

Although there have been several examples of flexible OLED displays on plastics, including passive-matrix OLED displays on poly(ethylene terephthalate) (PET) substrates from Pioneer and Universal Display Corporation [26, 27], and a-Si H TFT-driven monochrome active-matrix OLED displays on poly(ethylene naphthalate) (PEN) from Honeywell [28], there have been no demonstrations of organic TFT-... 

It is well known from diffusion theory that different types of polymers have different diffusion behaviours. For example, the polyester type polymers like poly(ethylene terephthalate) (PET), poly(ethylene naphthalate) (PEN) and polycarbonate (PC) as well as rigid poly(vinyl chloride) (PVC), which have a high glass transition temperature, are low diffusive polymers. The migration of potential contaminants in these polymers will result in low migration values. In contrast, polyolefins like high density polyethylene (HDPE), polypropylene (PP) or low density polyethylene (LDPE), which... 

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