Photochemical Degradation Study of Polyurethanes as Relic Protection Materials by FTIR‐ATR

Wang, Liqin; Liang, Guozheng; Dang, Gaochao; Wang, Fang; Fan, Xiaopan; Fu, Wen

doi:10.1002/cjoc.200591257

Cited by 16 publications

(18 citation statements)

References 19 publications

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“…Subsequently, the intermediate (II) may also result from the cleavage of the carbamate bond (C-N) in a similar way. These two types of scissions were consistent with previously reported results [33,37]. The presence of hydroxyl groups and adsorbed water molecules on the surface of TiO 2 particles (Fig.…”

Section: Photodegradation Mechanismsupporting

confidence: 92%

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Consideration of roles of commercial TiO2 pigments in aromatic polyurethane coating via the photodegradation of dimethyl toluene-2,4-dicarbamate in non-aqueous solution

Zhou

Xiao

et al. 2015

Res Chem Intermed

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Dimethyl toluene-2,4-dicarbamate (2,4-TDC) was selected as a model compound for aromatic polyurethane to investigate the photo-chemical behavior of commercial TiO 2 pigments in non-aqueous solution. The UV-Visible spectrometry analysis results showed that the UV-shielding ability of the rutile TiO 2 pigment was better than that of the anatase TiO 2 pigment. Photodegradation experiments suggested that the photodegradation of 2,4-TDC was retarded by rutile TiO 2 pigment, while accelerated by anatase TiO 2 pigment. With the help of the degradation intermediates during the photodegradation process and calculated data, such as point charges and bond length, the preliminary photodegradation mechanism of 2,4-TDC was also briefly elucidated, including the addition of hydroxyl radicals and the cleavage of the carbamate side chain. Additionally, the photodegradation of 2,4-TDC was used to evaluate the photoreactivity of TiO 2 pigments, this is proved to an efficient approach with potential application in industry.

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Section: Photodegradation Mechanismsupporting

confidence: 92%

“…The [33] have proposed a mechanism of the photochemical degradation of PU included the re-reactions of radical groups formed in the scission reactions. However, the degradation intermediates formed from the re-reactions of radical groups was not detected in our work, probably due to their low concentrations.…”

Section: Photodegradation Mechanismmentioning

confidence: 99%

Consideration of roles of commercial TiO2 pigments in aromatic polyurethane coating via the photodegradation of dimethyl toluene-2,4-dicarbamate in non-aqueous solution

Zhou

Xiao

et al. 2015

Res Chem Intermed

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“…Given the lack of an obvious IR absorbance component due to R6G -with its contributions overwhelmed by the polymer -it is difficult to say definitively that observed changes are due to the dye and/or host. However, we find that the observed changes are consistent with previous studies of photodegradation in neat PU [56][57][58][59][60][61][62] and therefore we proceed with the assumption that the changes in the IR absorbance spectrum are due to the polymer and not the dye. Figure 16 shows the change in IR absorbance of the sample due to conditioning and degradation.…”

Section: Ftir Measurementssupporting

confidence: 84%

“…Table I lists the peak locations and their assignments. Based on the location and behavior of the peaks -as well as previous studies on neat polyurethane [56][57][58][59] -we can make several conclusions about the peak behavior:…”

Section: Ftir Measurementsmentioning

confidence: 92%

Photodegradation and self-healing in a Rhodamine 6G dye and $$\hbox {Y}_{2}\hbox {O}_{3}$$ nanoparticle-doped polyurethane random laser

2015

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One of the fundamental difficulties in implementing organic dyes in random lasers is irreversible photodegradation of the dye molecules, leading to loss of performance and the need to replace the dye. We report the observation of self-healing after photodegradation in a Rhodamine 6G dye and nanoparticle doped polyurethane random laser. During irradiation we observe two distinct temporal regions in which the random lasing (RL) emission first increases in intensity and redshifts, followed by further redshifting, spectral broadening, and decay in the emission intensity. After irradiation the emission intensity is found to recover back to its peak value, while still being broadened and redshifted, which leads to the result of an enhancement of the spectrally integrated intensity. We also perform IR-VIS absorbance measurements and find that the results suggest that during irradiation some of the dye molecules form dimers and trimers and that the polymer host is irreversibly damaged by photooxidation and Norrish type I photocleavage.

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“…333 6c) were also reduced after exposure to UV for 28 h, indicating a loss of aromatic groups on the 334 sample surface. As a result, the loss of the aromatic urethane structure as indicated by both the 335 urethane and aromatic groups suggests possible chain scission and photo-Fries rearrangement of the 336 urethane group during photodegradation [43, 45,46]. Meanwhile, a new shoulder appearing at 337 1654 cm −1 could be recognised as the deformation of N-H bonds in primary amine groups formed 338 during UV ageing [47].…”

mentioning

confidence: 99%

Early-stage photodegradation of aromatic poly(urethane-urea) elastomers

Zhang

Xie

Motuzas

et al. 2018

Polymer Degradation and Stability

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16The photooxidative stability of an aromatic segmented poly(urethane-urea) (PUU) elastomer, 17 stabilised with a range of carbon black fillers, was assessed after very low UVA doses as a means to 18 identify components that are highly susceptible to UV degradation, and suggest better design of such 19 materials. Fourier-transform infrared (FTIR) analysis indicated rapid degradation of the urea bonds 20 in the hard segments, followed by chain scission and photo-Fries reaction of the urethane linkages. In 21 the soft segments, the oxidation of the original ether groups resulted in the formation of large 22 amounts of ester groups, while some crosslinking of the ether groups was also evident. Carbon black 23 provided moderate protection against degradation, with the smallest-sized particles being the most 24 effective. Protection was evidenced by reduced surface cracking as well as an increased resistance to 25 chemical changes in both the soft segments and hard segments. Even so, significant degradation was 26 still evident at low UV doses suggesting that further stabilisation is required to increase the UV 27 durability of these elastomers and improve their long-term performance. 28 29 Keywords: UV ageing; aromatic poly(urethane-urea); carbon black 30 system. PUUs have been found to exhibit better photostability than their polyurea counterparts [19]. 53However, due to limited work in this area, a complete description of the PUU photodegradation 54 process and how the UV irradiation affects the properties of PUU remain unclear. 55 effects of three types of carbon black with different structural characteristics on the UV stability of 77 this PUU were also studied. The photodegradation processes were analysed using Fourier-transform 78 infrared (FTIR) studies of the PUU surface chemistry over the monitoring period, along with other 79 techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), 80 119 2.3 Accelerated UV ageing 120 Samples were cut from 2.5-3.5 mm thick flat sheets and loaded into custom-built extensometers 121 according to ASTM D1149-16 using Method B, Procedure B1 -Straight Specimens (Static 122 Elongation). The accelerated ageing method was adapted from UV Resistance MIL-STD-810G, 123Method 505.5, Procedure II (A2). Briefly, samples were loaded into a QUV accelerated weathering 124 tester (Q-Lab, Ohio, USA) that was equipped with UVA-340 lamps. The samples were held at 50°C 125 143 X-ray photoelectron spectroscopy (XPS) 144Surface analysis was performed on a Kratos Axis ULTRA X-ray photoelectron spectrometer 145 (XPS) using monochromatic Al Kα (hν = 1486.6 eV) radiation. Curve fitting was undertaken using a 146Gaussian-Lorentzian peak shape and Shirley background function. The binding energy was poly (etherurethane urea)

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Photochemical Degradation Study of Polyurethanes as Relic Protection Materials by FTIR‐ATR

Cited by 16 publications

References 19 publications

Consideration of roles of commercial TiO2 pigments in aromatic polyurethane coating via the photodegradation of dimethyl toluene-2,4-dicarbamate in non-aqueous solution

Consideration of roles of commercial TiO2 pigments in aromatic polyurethane coating via the photodegradation of dimethyl toluene-2,4-dicarbamate in non-aqueous solution

Photodegradation and self-healing in a Rhodamine 6G dye and $$\hbox {Y}_{2}\hbox {O}_{3}$$ nanoparticle-doped polyurethane random laser

Early-stage photodegradation of aromatic poly(urethane-urea) elastomers

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