Radiation effects on the thermal degradation of poly(vinyl chloride) and poly(vinyl alcohol)

Zhao, Wenwei; Yamamoto, Yukio; Tagawa, Seiichi

doi:10.1002/(sici)1099-0518(199812)36:17<3089::aid-pola10>3.0.co;2-b

Cited by 33 publications

(14 citation statements)

References 22 publications

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“…The transmission intensity for samples d1 and d2 increased with respect to the transmission intensity of sample d in the wavelength range of 220–320 nm. With an increasing incident energy density, the transmission intensity for samples d1, d2, f1, and f2 in the wavelength region of 350–900 nm was decreased because the UV radiation‐induced chemical reactions of vinyl polymers include, in general, crosslinking, chain scission, small molecular elimination, and internal or terminal double‐bond formation 21…”

Section: Resultsmentioning

confidence: 99%

Sensing Chiral Drugs by Using CdSe/ZnS Nanoparticles Capped with N‐Acetyl‐L‐Cysteine Methyl Ester

Delgado-Pérez

Bouchet

Guárdia

et al. 2013

Chemistry A European J

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Chiral quantum dots (QDs), differing in their core or shell size and, consequently, in their optical properties, were synthesized by the treatment of commercially available amine-capped quantum dots with methyl ester N-acetyl-L-cysteine (CysP). Interestingly, their colloidal methanol solutions remain stable for several months. Their NMR and IR spectra were in accordance with CysP binding to the QD surface through two anchoring groups; its thiolate (strongly bound) and the carbonyl group of its ester (weaker bound) group, whereas their circular dichroism (CD) spectra showed a new broad redshifted band, suggesting that the attachment to the QD surface modified the conformational equilibrium towards conformer(s) with optical activity in this region. These QDs were sufficiently fluorescent to perform studies of the chiral recognition of drugs, in particular the aryl propionic acids (APAs) ketoprofen (KP), naproxen (NP), flurbiprofen (FP), and ibuprofen (IP). We used different drug concentration ranges, depending on the QD solubility. All the assayed drugs quenched the QD emission in a concentration-dependent mode. Quenching fluorescence assays with the chiral QDs (CS@CysP) showed their extraordinary capacity for the chiral recognition of KP, NP, and FP, and particularly in the case of KP and FP, a remarkable positive allosteric effect was detected for the R enantiomer. By using a drug/CS@CysP molar ratio of 5000:1 and 2500:1, the changes of intensity and the sign of the CD spectrum of the drug evidenced the dissociation of the drug carboxylic group in the presence of the QD.

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Section: Resultsmentioning

confidence: 99%

Sensing Chiral Drugs by Using CdSe/ZnS Nanoparticles Capped with N‐Acetyl‐L‐Cysteine Methyl Ester

Delgado-Pérez

Bouchet

Guárdia

et al. 2013

Chemistry A European J

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“…The increase in fluorescence intensity that is observed for the high dose samples is likely explained by production of conjugated double bond (C]C) species within the polymer during irradiation, as discussed in a previous study [18]. Presence of conjugated double-bond moieties resulting in polymer fluorescence has also been observed during the thermal degradation of other polymers [20][21][22][23][24]. Further evidence for the existence of C]C species is observed in the FTIR analysis of a-irradiated PTFE samples, and is discussed below.…”

Section: Dscmentioning

confidence: 99%

Cross-linking of polytetrafluoroethylene during room-temperature irradiation

Pugmire

Wetteland

Duncan

et al. 2009

Polymer Degradation and Stability

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a b s t r a c tExposure of polytetrafluoroethylene (PTFE) to a-radiation was investigated to determine the physical and chemical effects, as well as to compare and contrast the damage mechanisms with other radiation types (b, g, or thermal neutron). A number of techniques were used to investigate the chemical and physical changes in PTFE after exposure to a-radiation. These techniques include: Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and fluorescence spectroscopy. Similar to other radiation types at low doses, the primary damage mechanism for the exposure of PTFE to a-radiation appears to be chain scission. Increased doses result in a change-over of the damage mechanism to cross-linking. This result is not observed for any radiation type other than a when irradiation is performed at room temperature. Finally, at high doses, PTFE undergoes mass-loss (via small-fluorocarbon species evolution) and defluorination. The amount and type of damage versus sample depth was also investigated. Other types of radiation yield damage at depths on the order of mm to cm into PTFE due to low linear energy transfer (LET) and the correspondingly large penetration depths. By contrast, the a-radiation employed in this study was shown to only induce damage to a depth of approximately 26 mm, except at very high doses.

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“…These results could be explained as follows. The principal radiolysis effect of PVA is to evolve hydrogen 13. The loss of one hydrogen atom from the α‐carbon of hydroxyl group produces a main intermediate, α‐hydroxyalkyl radical, and ultimately gives carbonyl groups by loss of another hydrogen atom.…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic behavior of poly(vinyl alcohol) films with different molecular weights after UV irradiation, thermal annealing, and double treatment with UV irradiation and thermal annealing

El-Kader

2003

J of Applied Polymer Sci

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Pure poly(vinyl alcohol) (PVA) films with molecular weights 5,000, 72,000, and 125,000 g/mole were prepared by casting technique. The thickness of prepared samples was 0.21 mm. Xenon arc lamp was used to irradiate two samples from each molecular weight at 400 W for 5 min. One from each irradiated PVA samples was heated at 423 K for 2 h. An additional PVA sample unirradiated from each molecular weight was heated at 423 K for 2 h. Optical absorption measurements have been carried out in the wavelength range of 190 -900 nm for untreated, UV-irradiated, heated, and double-treated samples by UV irradiation and heat. The double-treated PVA samples with molecular weights 5,000 and 72,000 g/mole showed approximately zero transmission in comparison with untreated PVA sample in the wavelength range of 190 -320 nm. PVA sample with 125,000 g/mole was irradiated with 600 W for 5 min to obtain the zero transmission in the same wavelength range. Identification of the structure and assignments of energy bands were studied also by using FTIR.

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Radiation effects on the thermal degradation of poly(vinyl chloride) and poly(vinyl alcohol)

Cited by 33 publications

References 22 publications

Sensing Chiral Drugs by Using CdSe/ZnS Nanoparticles Capped with N‐Acetyl‐L‐Cysteine Methyl Ester

Sensing Chiral Drugs by Using CdSe/ZnS Nanoparticles Capped with N‐Acetyl‐L‐Cysteine Methyl Ester

Cross-linking of polytetrafluoroethylene during room-temperature irradiation

Spectroscopic behavior of poly(vinyl alcohol) films with different molecular weights after UV irradiation, thermal annealing, and double treatment with UV irradiation and thermal annealing

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