Absorption spectra polyethylene

In the process of inhibition polypyrocatechin borate interacts with polyethylene macroradicals to form the B—O—C bonds. This is confirmed by the fact that the absorption spectrum of polyethylene inhibited with polypyrocatechin borate revealed the bands in the region of 1350 cm" characteristic for the B—O—C bond. There is no such a band in the spectrum of pure polypyrocatechin borate after heating under the same conditions. Chemical analysis of boron in polyethylene provides support for the IR-spectroscopy data concerning the presence of chemically bonded boron in polyethylene after destruction. 

Fig. 6.2 Absorption spectrum of silver nanoparticles prepared from an aqueous solution (70 ml) of AgN03 (0.2 mM) containing polyethylene glycol (0.1 wt%) and ethylene glycol (0.1 M)...

Narrow Component. As discussed in Chapter II, the absorption spectrum for polyethylene cannot be described by a single Lorentzian even in the molten state. However, the deviation from one Lorentzian is not enhanced for well-fractionated samples in the melt and, furthermore, becomes negligible as the temperature decreases42. Accordingly, the differential form of a Lorentzian distribution can be used for the elementary spectrum of the narrow component ... 

Delhez, R. Ultraviolet Absorption Spectrum of Water Stored in Polyethylene Bottles. Chemist-Analyst 49, Heft 1, S. 20 (1960). 

Figure 16 shows the absorption spectrum obtained by additive-free polyethylene [67], At ambient temperature the absorption observed on nanosecond time-scale increased continuously from 500 to 200 nm without showing any maximum. The absorption in UV is similar to that obtained by y-irradiation. Considering the results obtained by liquid alkanes, the absorption seems to be comprised of several different free radicals. At 95 K additional absorption due to the trapped electron was observed at wavelengths longer than 600 nm the band was observable even at ambient temperature in the picosecond time-domain [96]. The electron decays presumably by the hole-electron recombination. The decay of the trapped electron was independent of the presence of carbon tetrachloride, suggesting that the additives reacted with a mobile electron but not with the trapped electron. On adding naphthalene, the radiation-induced spectrum showed the bands due to the first excited triplet state and the radical... 

Delhez, R. (1960). Ultraviolet absorption spectrum of water stored in polyethylene bottles. Chemist-Analyst 49, 2Q-21. 

The absorption spectrum and the photostability of ultraviolet absorbers are not the only factors to be taken into account. In order to be efficient the additive should also be compatible with the polymer and be in true solution. This condition is not always easy to fulfil with highly crystalline polymers. From this viewpoint the nature of the substituents is very important. It has been observed that polyethylene is better protected by 2-hydroxy-4-dodecyloxybenzophenone or 2-hydroxy-4-octyloxybenzo- phenone than by 2-hydroxy-4-methoxybenzophenone [142]. This has been attributed to better compatibility and lower rate of loss by diffusion the long alkyl substituted derivatives. 

Fig. 4.3 IR absorption spectrum of polyethylene 1. Single-beam reference spectrum (without sample) 2. single-beam sample spectrum 3. ratioed transmission spectrum.

NEAR-ULTRAVIOLET ABSORPTION SPECTRUM OF POLYETHYLENE. PARTRIDGE R H... 

The two electrons transferred from TDAE to PEDOT-PSS are expected to undope the conjugated polymer chains. Since TDAE diffuses into PEDOT-PSS, long exposures to the electron donor induce changes in the optical properties of the polymer film. Optical absorption experiments on 200 nm thick PEDOT-PSS films coated onto a transparent polyethylene terephthalate (PET) substrate. The pol5mier film was exposed to the TDAE vapor in an inert nitrogen atmosphere and shows the difference in absorption spectrum between a film exposed to TDAE and the pristine PEDOT-PSS layer (Figs. 3.10 and 3.11). The modification of the optical properties and the sheet resistance of the pol5mier layer were recorded versus exposure time. The two absorption features at 550 nm and... 

The absorption spectrum of the OECC purified from P.la-minosum grown in Fe-enriched medium showed main peaks at 674, 492, 435 and 414 nm (Fig. 1). The last step of purification, i.e. precipitation with polyethylene glycol, eliminated considerable amounts of phycobiliproteins, absorbing between 600-650 nm, which usually contaminate this kind of preparation. The bands at 674 and 435 nm are due to Chi and that at 414 nm is mainly due to the cytochrome b-559. The carotenoids absorb in the 492 nm region. The OECC preparation showed an O2-evolution rate of 2,000 /wnol. mg Chl . hT, ... 

Figure 10 shows the VUV absorption spectrum for polyethylene [16]. This is typical for polymers. The absorption coefficients are extremely high so the VUV raffiation is absorbed in a very shallow depth in the surface of the polymer. The absorbed photons will break surface bonds and generate surface free-radicals which can then react with the boundary layer gas, which will have a different composition than the plasma gas. 

The absorption spectrum of polyethylene in the far infrared is very simple a broad background increasing to higher frequencies and only one sharp band at 73 cm. Figure 15 shows an example for a high density polyethylene (HDPE). The background comes from the amorphous part of the material, which can be described in terms of the variable Brillouin zone. The absorption band itself, called the "73 cm band," is generated by a lattice vibration of the orthorhombic lattice, which is shown in Fig. 16. 

Fig. 15. Absorption spectrum of polyethylene (HOPE, 6011L) at room temperature in the far infrared.

Fig. 61. Influence of ultraviolet irradiation of polyethylene on the structure of the infrared absorption spectrum, a) Before irradiation b) after 89 hr irradiation by UV light.

Figure 3-8. Infrared absorption spectrum of highly crystalline polyethylene where crystal field splitting is shown in the 1450 and 720 cm range due to crystal field splitting (crystaUinity bands).

Polyethylene should, in theory, be photo-oxidatively stable on the basis of its formal -(-CHj—CH2 structure however commercial polyethylenes are not photostable. This can be due to the presence of internal and external impurities (photoabsorbing chromophores) which are formed during synthesis and processing (cf. section 3.1.6). The UV irradiation of polyethylene in air causes an increase in its absorption spectrum (Fig. 3.5). 

In fig, 1 (as an example in our discussion) we report a comparison of the calciilated unweighted density of vibrational states of a perfect single chain of polyethylene with the actual infrared absorption spectrum. For a perfect trans planar chain of polyethylene with D2h symmetry the structure of the irreducible representation for k = 0 modes and the corresponding infrared and Raman activities for a stretch oriented rod in the one dimensional model are... 

Pig, 1 - Comparison between the infrared absorption spectrum of polyethylene with the density of vibrational states calculated for a perfect polymethylene single chain. The spectroscopic activity (Raman and Infrared) of the k = 0 critical points are indicated. 

Figure 14 shows the ATR spectrum of the etched polyethylene surface treated with a chronic acid group [76]. Absorption bands due to surface treatment appear at 3300, 1700, 1260, 1215, and 1050 cm". The band at 3300 cm represents the absorption due to the hydroxyl group and that at 1700 cm " is due to the carbonyl group. The bands at 1260, 1215, and 1050 cm are all due to the alkyl sulfonate group. 

While the control resins were deep red in color due to the presence of soluble porphyrin complexes, the methacrylate resins obtained after removal of the polyethylene-supported catalysts varied from light yellow to nearly water-white (APHA < 25). UV-Vis spectrophotometric analysis of the yellow resins indicated an absorption signal for the cobalt porphyrin complex Soret band (wavelength of cobalt(ll) porphyrin species appears at -415 nm free porphyrin ligand is formd at -423 tun). Resin samples that visttally appear as water-white show little or no porphyrin species present in the spectrum. Measured catalyst activity and PDl of the polyethylene-supported porphyrin complexes are in the expected range for soluble porphyrin CCT catalysts (PDl = M /Mn - 1.2- 2.0)." The screening resrrlts clearly... 

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