Polychloroprene degradation by a Photo-Fenton process

Freitas, Adonilson R.; Vidotti, Gentil J.; Rubira, Adley F.; Muniz, Edvani C.

doi:10.1016/j.polymdegradstab.2004.10.003

Cited by 20 publications

(17 citation statements)

References 17 publications

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“…The carbonyl index of the foils with VО(aсaс) 2 was also in the range 0.02 -0.07. The values of this index determined for the Fe(acac) 3 and VО(aсaс) 2 foils coincided with these for the initial HDPE despite their concentration in the compositions (Figure 2). This indicates that the use of Fe(acac) 3 and VО(aсaс) 2 as pro-oxidants by the photooxidation of the polymer was not effective.…”

Section: Resultssupporting

confidence: 69%

“…The values of this index determined for the Fe(acac) 3 and VО(aсaс) 2 foils coincided with these for the initial HDPE despite their concentration in the compositions (Figure 2). This indicates that the use of Fe(acac) 3 and VО(aсaс) 2 as pro-oxidants by the photooxidation of the polymer was not effective. It was proved on the basis of the FT-IR analysis that additives of manganese (II) and cobalt (III) acetylacetonates in concentrations 2 mmol/kg polymer are better be used to obtain higher degree of photooxidation.…”

Section: Resultssupporting

confidence: 69%

“…Therefore stability of HDPE under oxidation is higher than that of LDPE, as it has been reported 27 . The samples containing Fe(acac) 3 showed small increase of the carbonyl index from 0.025 to 0.075. This was due to reactions of chain scission as a result from the photooxidation which lead to formation of fragments of lower molecular weight 28 .…”

Section: Resultsmentioning

confidence: 94%

“…The only exception were the compositions containing 2 and 4 mmol/kg polymer Fe(acac) 3 for which the strength measured was close or the same as that of the irradiated HDPE. The decrease of the strength of the initial HDPE foils was more pronounced for the samples with pro-oxidants Со(aсaс) 3 and Mn(aсaс) 2 at irradiation durations 35 -150 h (Figure 3). For the Mn(aсaс) 2 containing foils, it decreased as low as 6 -7 MPa after 35 h irradiation to reach 5 MPa after 60 h (Figure 3).…”

Section: Resultsmentioning

confidence: 98%

“…Introduced as various complexes, the salts of polyvalent metals accelerate the interaction of polymers with oxygen from the air [1][2][3][4] by including oxygen atoms in the polyolefin chains.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Metal Acetylacetonates on the Photooxidative Destruction of High Density Polyethylene

2016

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The process of photooxidative destruction of high density polyethylene films containing different organic complexes of polyvalent metals as pro-oxidant additives after UV-irradiation was studied. During exposure to UV-irradiation, the more significant changes in the mechanical and thermal properties were detected for the foils containing pro-oxidant additives compared to initial high density polyethylene. This indicated for the higher degree of oxidation in these samples and confirmed the effectiveness of thеsе additives in promoting the oxidation of high density polyethylene during UV-irradiation. It was found that the decrease of the strength of the initial high density polyethylene foils was more pronounced for the samples with pro-oxidants cobalt (III) acetylacetonate and manganese (II) acetylacetonate. The use of 2 mmol/kg iron (III) acetylacetonate and 4 mmol/kg cobalt (III) acetylacetonate as pro-oxidants gave the highest decrease of elongation at break of the polyethylene foils.

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Section: Resultssupporting

confidence: 69%

Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Effect of Metal Acetylacetonates on the Photooxidative Destruction of High Density Polyethylene

2016

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Fragmentation of Fluorinated Model Compounds Exposed to Oxygen Radicals: Spin Trapping ESR Experiments and Implications for the Behaviour of Proton Exchange Membranes Used in Fuel Cells

2008

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Low-molecular weight model compounds (MCs) for Nafion membranes used in fuel cells were exposed at 300 K to Á OH radicals produced by UV irradiation of aqueous H 2 O 2 solutions. The MCs contained fluorinated and partially fluorinated groups terminated by sulphonic or carboxylic acid groups. The fragmentation process in the MCs was studied by spin trapping electron spin resonance (ESR) methods, using 5,5-dimethylpyrroline-N-oxide (DMPO), N-tert-butyla-phenylnitrone (PBN) and 2-methyl-2-nitrosopropane (MNP) as the spin traps. The objective of these experiments was to assess the effect of the type of ionic groups (sulphonic or carboxylic) and of fluorine substitution on the spin adducts detected. DMPO experiments led to the detection of spin adducts of Á OH and of carbon-centred radicals (CCRs), and allowed the determination of the Á OH attack site on the ionic and/or on the protiated or fluorinated groups. CCR adducts were also detected when using PBN as a spin trap; a key point in the interpretation of the PBN results was, however, the realisation that MNP is formed during PBN exposure to UV irradiation and oxygen or other oxidants such as H 2 O 2 . Experiments with MNP as the spin trap were the most informative in terms of structural details for adducts obtained from each MC. The results allowed the identification of CCRs present as adducts, based on large hyperfine splittings (hfs) from, and the number of, interacting 19 F nuclei; in addition, oxygen-centred radicals (OCRs) as MNP adducts were also identified, with much lower hfs from 19 F nuclei. Taken together, the results deduced by spin trapping suggest that both sulphonic acid and acetic acid groups can be attacked by Á OH radicals and confirm two possible degradation mechanisms in Nafion membranes: initiated at the backbone and at the side chain.

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Effect of carbon black on self-crosslinking network structure of polychloroprene rubber and epoxidized natural rubber blends

Wang

Zhang

et al. 2015

Polym. Compos.

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The goal of this research is to improve poor network structure of polychloroprene rubber (CR)/epoxidized natural rubber (ENR) self-crosslinking blends, which could substitute traditional vulcanizates in some application area. Carbon black (CB)-CR/ENR blends were prepared by reacting CR with ENR in the presence of CB. The structure of CR/ENR blends was characterized by attenuated total-reflectance Fourier transform infrared spectroscopy (FTIR-ATR). The effect of CB loading on curing characterization and mechanical properties of CR/ENR blends was investigated, and the interaction among CR, ENR, and CB was studied using differential scanning calorimetry. The effect of CB loading on the Payne effect of CR/ENR was investigated using rubber process analyzer. Scanning electron microscope was used to characterize the morphology of CB-CR/ENR blends. The results showed that CR/ENR blends were obtained by the ring-opening reaction of epoxy groups in ENR and chlorine groups in CR. Mechanical properties of CR/ENR blends increased with the increase of CB loading. The Payne effect of CR/ENR became more remarkable with increasing CB loading. Morphology study indicated that interfacial compatibility between CR and ENR increased with the increase of CB loading because CB could strengthen the self-crosslinking network structure of CR/ENR blends. The promoting effect of CB on selfcrosslinking reaction was verified by the assessment of crosslink density. POLYM. COMPOS., 00:000-000, 2015.

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Polychloroprene degradation by a Photo-Fenton process

Cited by 20 publications

References 17 publications

Effect of Metal Acetylacetonates on the Photooxidative Destruction of High Density Polyethylene

Effect of Metal Acetylacetonates on the Photooxidative Destruction of High Density Polyethylene

Fragmentation of Fluorinated Model Compounds Exposed to Oxygen Radicals: Spin Trapping ESR Experiments and Implications for the Behaviour of Proton Exchange Membranes Used in Fuel Cells

Effect of carbon black on self-crosslinking network structure of polychloroprene rubber and epoxidized natural rubber blends

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