Polyethylene terephthalate INDEX

Semicrystalline polyalkyl terephthalates are opaque due to diffraction of light as it crosses the interface between crystalline and amorphous regions. Amorphous polyethylene terephthalate has a low refractive index, making it appear glass-like in quenched parts. 

Careful work is necessary to remove all preferred orientation from powder samples. Figure 1 shows results obtained with polyethylene terephthalate (PET) fibers. Curve is a typical azimuthal scan of the 010 peak (20 = 17,5°) for a bundle of parallel fibers placed perpendicularly to the x-ray beam. Curve b is the same scan carried out on a "powder" sample, showing that all preferred orientation is removed in our conditions of moulding (350 kg/ m2). For each kind of fiber, it is necessary to do preliminary trials to find the best experimental conditions. For PET fibers, we show on Figure 2 the relative crystallinity index and the residual orientation plotted against the cut-lengh. (5). 

Crystallinity is important in determining optical properties because the refiaetive index of the crystalline region is always higher than that of the amorphous component irrespeetive of whether the amorphous component is in the glassy or rubbery state. This difference in refractive indices of the component phases leads to high scattering and consequently, the translucency or haziness of semicrystalline polymers. For a purely amorphous polymer, this does not occur, and hence amorphous polymers are usually transparent. Therefore the state of polyethylene terephthalate can be explained as follows ... 

Stackman [29] carried out a study to find systems suitable for reducing the flammability of polyethylene terephthalate (PET) and poly-1,4-butylene terephthalate (PBT) while retaining the chemical and physical properties of the original polymers. The additives used were phosphine oxides, phosphonates and phosphates and their activity was assessed by means of an oxygen index test. Most of the phosphorus esters were found to be volatile under the blending conditions and both the halogenated phosphorus esters and halogenated derivatives of phosphorus oxide proved to be ineffective as flame retardants. 

Shabana H. M. (2004). Refractive index-structure correlation in chemically treated polyethylene terephthalate fibers. Polymer Testing, Vol. 23, pp. 291-297, ISSN 0142-9418... 

The majority of results so far available in this Held have been derived from spectra recorded on dispersive instruments. In order to test tl validity of Eq. (1) several independent experiments have been performed in which a highly oriented polyethylene terephthalate film is subjected stepwise to increasingly higher stresses in the stretching machine illustrated in Fig. 1 and FTIR spectra are taken at the relaxed stress levels with unpolarized radiation. In Fig. 4 the wavenumber shifts of the v(0—CH2) absorption band are plotted as a fimctimi of the applied stress for different experiments. From these systematic investigations, however, no linear relationship between the wavenumber shift Av and the plied stress good index of determination (0.98) was obtained for the power function ... 

Tillier and co-workers [49] carried out structural molecular weight and end-group studies on copolyesters of polyethylene terephthalate (PET) and e-caprolactone using GEC and MALDI-ToF-MS. The measurement of molar mass by MALDI-ToF-MS was shown to be inapplicable in the case of polymers exhibiting a polydispersivity index (1 ), greater than 1.10 such as PET and others. 

The long-term, continuous-use temperature resistance ranges from about 120 to 125 °C, as measured by the UL 746B relative thermal index (RTI) test, which places its performance closer to that of the engineermg polymers such as polybutylene terephthalate (PBT), liquid crystal polymers (LCP), and polyethylene terephthalate (PET) than to that of performance polymers such as polyphenylene sulfide (PPS), polyether sulfone (PES), and polyamide imide (PAI). 

Figure 14.32 The flame resistance of polymeric materials, indicated by the oxygen index. 1, polyformaldehyde 2, polyethylene, polypropylene 3, polystyrene, poiyisoptene 4, polyamide 5, cellulose 6, poly(vinyl alcohol) 7, poly(ethylene terephthalate) 8, polyactylonitrile 9, poly(phenylene oxide) 10, polycarbonate 11, aromatic nylon 12, polysulfone 13, Kynol 14, polylmide 15, carbon. Polymers producing large values of char residue are more fire resistant.

Acronyms and variables cold crystalhzation (CC) cobalt molybdenum catalyst (CoMoCAT) chemical vapor deposition (CVD) dichlorobenzene (DCB) high-pressure carbon monoxide (HiPCO) isotactic polypropylene (iPP) melt crystalhzation (MC) melt flow index (MFl) poly( -caprolactone) (PCL) polydispersity index (PDD polyethylene (PE) polyethylene oxide (PEO) poly (ethylene-propylene-diene) [P(E-PP-diene)] poly(ethylene 2,6-naphthalate) (PEN) poly(ethylene terephthalate (PET) poly(L-lactic acid) (PLLA) poly(trimethylene terephthalate (PTMT) poly(vinyl alcohol) (PVA) 1,1,2,2-tetrachloroethane (TCE) tetrahydrofuran (THE) weight-average molecular weight = ] number-average molecular weight Avrami exponent for neat polymer = Avrami exponent for CNT composite = Avrami rate constant for neat polymer = Avrami exponent for composite = neat polymer crystalhzation... 

Polybutylene adipate - polybutylene sebacate Polybutylene sebacate - polybutylene succinate Polybutylene sebacate - polybutylene succinate Polybutylene terephthalate Polydispersivity index Polydimethyl siloxane Polyethylene Polyethylene glycol(s)... 

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