Polyethylene terephthalate, identification

The above-mentioned method is effective in identifying the molecules of detected ions. However, because PVDF film is not permeable to light, it is difficult to observe tissue sections. To resolve this problem, we developed a method to fix tissue sections on transparent film, and then performed MS on those sections.6 We used a conductive film because we expected the ionization efficiency would increase when the electric charge accumulation on the sample was reduced. The film used for this purpose was a polyethylene terephthalate (PET) film with a thickness of 75-125 pm, having a 5 15-nm-thick layer of evaporated oxidation indium tin (ITO) upon it (ITO film). This film is used in touch-panel displays because of its high transparency and superior conductivity. We used it to perform MS/MS for tissue sections and succeeded in identifying multiple proteins from mass spectra.6 Therefore, the further development of this method will enable the application of the mass-microscopic method to observe tissue by optical microscope and to perform tandem mass spectrometry (MSn) at the observation part, simultaneously, enabling the identification of molecules included the part. 

Peebles, L. H., Huffmann, M. W. and Ablett, C. T Isolation and identification of the linear and cyclic oligomers of polyethylene terephthalate... 

These tests, however, do not identify certain chemically very inert plastics such as polyethylene, polypropylene, polyisobutylene, polystyrene, polymethyl methacrylate, polyacrylates, polyethylene terephthalate, natural rubber, butadiene rubber, polyisoprene, and silicones. Their identification requires specific individual reactions, described in Chapter 6. 

Polyethylene terephthalate and polybutylene terephthalate are soluble in nitrobenzene. For their identification, pyrolyze a small sample of the solid plastic in a glass tube covered with filter paper. First, drench the filter paper with a saturated solution of o-nitrobenzaldehyde in dilute sodium hydroxide. A blue-green color (indigo), which is stable against dilute hydrochloric acid, indicates terephthalic acid. 

Solubility tests permit at least a tentative identification of the components also in polymer blends. Blends of ABS and polycarbonate are soluble in most polar solvents. Solubility in tetrahydrofuran and methyl ethyl ketone demonstrates the absence of polyolefins in such blends and the presence of aromatic polyesters or of polyamides can also be excluded. On the other hand, generally they may contain such highly soluble polymers as polystyrene, PVC, ABS, or polymethacrylates. However, blends that contain polybutylene terephthalate or polyethylene terephthalate do not dissolve in the usual solvents, but require m-cresol, which can he a clear indication that aromatic polyesters are present. Polyolefins dissolve at high temperatures, at least 110 °C, in toluene and p-xylene, and this behavior is characteristic of blends that contain polyethylene or polypropylene. 

The quality of the spectra obtained in two minutes is more than adequate for qualitative identification. Differences in crystallinity are readily seen for both PP and polyester samples. Some common inorganic fillers such as glass and talc are weak Raman scatterers and are not evident in the spectra. In other cases inorganic fillers are seen, e.g., BaS04 in voided polyethylene terephthalate film. 

For many years the Society of the Plastics Industry, Inc. (SPI) in the United States has romoted a voluntary coding system for the identification of the resins used in rigid plastic containers. The system comprising a number 1 to 7 and several letters is generally moulded into the bottom of a container. For example, the number 1 and the letters PETE indicates that the container is made of polyethylene terephthalate while the number 2 and the letters HDPE signify that the container is comprised of high density polyethylene. Thirty-nine U.S. states have mandated that plastic bottles 16 ounces or more and other rigid plastic containers of 8 ounces or more must carry the SPI resin code. 

Perfluoroethylenes have been characterized by desorption chemical ionization and tandem mass spectrometry Fourier transform ion cyclotron resonance mass spectroscopy has also been applied to the identification of polymers, eg. polyethylene glycols. Comparative complimentary plasma desorption mass spectrometry/secondary ion mass spectrometry has been applied to the identification of oligomers of various polymers including polyethylene glycol, polytetrafluoroethylene, polycarbonate, polyacrylates, polyethylene terephthalate and siloxanes. ... 

Demertzis and co-workers [48] carried out an in-depth study of the influence of gamma irradiation on the formation of solvent extractable radiolysis prodncts of flexible films and sheeting for food packaging. The packaging, which was made from PE, PP, polyethylene terephthalate (PET), PS, polyvinylchloride (PVC) and polyamide (PA), was subjected to Co irradiation at a dose of 44.0 kGy. Separation and identification of extracted compormds were carried out using GC-MS and compositional changes in the radiolysis prodncts quantified by calibration using MS detector response. 

Identification of plastics can be as simple as finding the resin identification code (typically on the bottom of the component) or as complex as separating the base resin from the filler, reinforcements, and colorants to analyze via infrared (IR) spectroscopy. The resin identification codes developed by the Society of Plastics Industry in 1998 are shown in Table 1.5. Despite the desire of many individuals to recycle, many communities recycle often only recycle plastics polyester (polyethylene terephthalate (PET)) and high-density polyethylene (HDPE). In fact, local recycling companies in the United States will often bury plastics in a landfill, either with the rest of the waste or in separate locations, ostensibly to mine at a later date. Collected recyclables are also shipped from the United States as baled... 

It can be seen that most containers and almost aU film materials arc potentially includwi in the 6 categories. There are several cautionary points to be observed. Except for poly(ethylene terephthalate), PET, containers arc not the predominant use for any one polymer. For poly (vinyl chloride), PVC, consumer-indentifiable containers are less than 10% of the total. TTie identification on products is not always very prominently displayed. It can take some effort to ascertain that a given grocery bag is either No. 2 (HDPE), high-density polyethylene, or No. 4 (LDPE), low-density polyethylene. And there is a problem with composite products. Even the symbol on the base of a 2-liter soda bottle is somewhat ambiguous. The symbol is No. 1 (PETE). While it is true that the clear bottle is, indeed, PET, the base (placwi over the round bottom of the bottle) is itself No. 2 (HDPE). Also, the bottle usually will contain small amounts of paper (label) and poly(vinyl acetate) (adhesive) in addition to a metal cap with a copolymer liner. 

The polymers are present in various sectors, activities, and in our day-to-day. The Brazilian Association of Technical Standards [3] establishes the identification of polymers that can be recycled, such as polypropylene (PP), poly(ethylene terephthalate) (PET), polyethylene (PE), poly (vinyl chloride) (PVC). 

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