PETP films

As a result of thermooxidative destruction, polyethylene terephthalate liberates the diethyl ether of terephthalic acid, acetaldehyde, methanol and carbon oxide. As investigations have shown, manufacture of PETP films or fibers has brought no change to the state of health of maintenance workers. Moreover, PETP films are used to preserve sterilized foodstuffs and warm up prepared dishes. 

Polymer Degradation and Stability 67, No. 1,2000, p. 149-58 FTIR STUDY OF THE EFFECT OF HYDROLYTIC DEGRADATION ON THE STRUCTURE OF THEV PETP FILMS Sammon C Yarwood J Everall N Sheffield,Hallam University ICI Research Technology Centre... 

The use of near-IR and far-IR spectroscopies for characterisation of PETP films was investigated. After a brief review of previous work, some examples of transmission spectra of annealed PETP, showing complex changes in the absorption bands, are presented. Near-IR spectroscopy was used to follow the crystallinity (or conformation) of thick PETP films without any sample preparation. 40 refs. 

Partial least-squares analysis was used to calibrate Raman microprobe spectra of PETP films in terms of density, to give insight into changes in crystallinity through the film thickness. The microprobe uses a static multiplexed holographic grating to obtain the entire Raman spectrum in a single shot. 13 refs. 

IR spectra of PETP films were obtained, with an excellent signal-to-noise ratio, by diffuse reflectance measurements on a KBr matrix using FTIR spectroscopy. All the spectra exhibited a new band at 1684 cm/1, characteristic of the C = 0 stretching vibration of a terminal acidic function in the presence of internal hydrogen bonds. These acidic functions may be used to monitor polymerisation rate. 19 refs. 

A critical assessment was made of the use of ATR-IR spectroscopy for the study of the surface composition and orientation in uniaxially drawn PETP films. The use of reference bands commonly used in such analyses was examined, paying particular attention to the possible deleterious effects of sample orientation, incident polarisation and sample contact. The use of conventional sampling procedures to obtain in-plane surface dichroism measurements is shown. 25 refs. 

Mylar polyester film is a product of the 50%/50% DuPont Teijin Films joint venture, dating from 1999, between DuPont and Teijin Limited. DuPont Teijin claims to be the world s leading supplier of PET and PEN polyester films and also supplies Melinex polyester film. Toray s joint venture in China is designed to produce PETP film for ultrathin capacitors. 

Fig. 9.31. Distribution of principal strain in front of a plane crack in biaxially drawn PETP film (after [202]).

A non-destractive technique for characterisation of the surface Tg in PETP is described which involves analysis of the variation of the ellipsometrically measured refiactive index with temp., using the spectral dependence of the penetration depth of light to discriminate between surface and bulk transitions. The surface Tg is shown to be lower than that of the bulk for spin-cast semicrystalline PETP films because of density variation and Tg is found to be lowered fiuther by plasma processing. 18 refs. 

Polarised confocal Raman microscopy was used to measure molecular orientation in uniaxially drawn PETP films, prepared with draw ratios from 1 to 3.5. The orientation of both polarised Raman microscopy and polarised attenuated total reflection IR spectroscopy. Crystallinity profiles were measured through the thickness of the film samples and compared with the orientation gradients existing in the films. This procedure was to determine whether the intuitive assumption that orientation and crystallinity would be positively correlated actually holds true on the microscopic scale for these samples. 18 refs. 

Polyethylene terephtalate (PETP) is a (saturated) polyester and is, like nylon, known for its large-scale use as a textile fibre. Moreover it is being applied at an increasing scale as a plastic, viz. in films, bottles (the PET-bottle ) and injection-mouldings. Though its stiffness decreases significantly above 70 °C, it remains a solid up to its melting point (255 °C). 

Harris and Ward have observed conventional crazes nearly normal to the tensile stress axis (tensiile crazes), as well as what appear to be crazes along the shear direction (shear crazes), in uniaxially drawn, crystalline PETP sheets. Tensile crazes were formed parallel to the initial draw direction. The shear crazes which were the first of their kind to be reported, were seen in specimens under all directions of orientation. They formed always at the same angle as that of the shear bands which appeared subsequently upon yielding. An explanation for this shear-craze -phenomenon was offered by Brady and Yeh based on their own studies of crazes and shear bands in amorphous and crystalline, isotactic PS films. First they produced a set of crazes and shear bands by stretching a film in one direction. When this film was then redrawn in a second direction, the authors observed that the stress component, which was... 

Polyethyleneterephthalate (PETP) is widely used in industry as fibres and films. PETP belongs to thermoplastic ethers and is a product of polycondensation of ethylene glycol and dimethylterephthalic acids [186],... 

Direction and rate of changes depend on wave length of incident light, intensity of radiation and PETP structure. Investigations [115] on the study of PETP fluorescence at excitation by light with wave length Z=34() mn show that excitation spectra depend on relation of emission intensity at Xmax37() and 390 mn and on film thickness. 

Plane structure of HC-2 must facilitate molecules aggregation of light stabilizer, that leads to very effective suppression of excited states. Computing of space configuration of hexaazocyclanes molecules also explains difference of properties of PETP - fibres and DAC films dyed by HC-3 and HC-4. 

As it is rather difficult to obtain film Irom PETP, then films, obtained from cellulose diacetate (CDA), modified by hexaazocyclanes were used as samples. 

Metal foil (predominantly aluminum) is introduced into combined film materials to attain vapor, gas and light impermeability, stiffness, thermal and chemical resistance, and shape stability in a package. These materials are often combined with paper. It is common experience to use combined films such as PE-foil, PE-foil-PE-paper-parafEn, PE-foil-PETP, PE-foil-PE-cellophane and many other combinations [8,14,29,32,34-36]. 

Polyesters form a large class of commercially important polymers. A typical polyester is poly(ethylene terephthalate) (PETP), the largest volume synthetic fiber. It is also used as film (mylar) and in bottle applications. We have already discussed in the preceding section one of the routes for the preparation of PETP. The traditional route for the production of commercial PETP is through two successive ester interchange reactions, as shown below ... 

A 2 mm wide ribbon of 1.5 pm thick PETP tape is to be used to construct a 1 pF capacitor. Calculate the length of tape necessary, given that the dielectric constant is 3.23 at 1 kHz. Calculate the resistance of the film at 50 °C using the data in Fig. 12.2, treating the geometry as a parallel plate capacitor. 

At pickling polycarbonates films (PC) by alkaline solutions, as well as in a case PETP, on their surface will be derivate a rough relief [15, 16], A source of origin of a roughness is the micro heterogeneities of submicroscopic sizes in structure of PC. Thus of a film of PC obtained by a methods of solution pouring (PCP) and extrusion (PCE) essentially differ. A PCP-film have more loose stracture [ 16] and find out after pickhng more advanced micro-relief, than PCE-film obtained by extrasion. 

The destruction of filaments PETP, as well as films, proceeds fium a surface [4, 28-31]. At destmction of molecules in alkali the decay goes under the law of a case [2,3] with subsequent depolymerisation. It means, that on a surface of a filament always there will be a stationaiy value stationary concentration ester bonds c , and the losses of a mass of polymer will be proportional to an amount broken ester bonds ... 

The surface structure of melt-mixed blends of bisphenol A polycarbonate and PETP was investigated by FTIR attenuated total reflectance spectroscopy. Based on the peak intensity of the aromatic carbonate band for polycarbonate and the aliphatic ester band for PETP by using germanium and KRS-5 ATR crystals, the enrichment of the PETP component in the surface layer of the polycarbonate/PETP blend films was observed. 27 refs. 

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