We investigated the concentration and composition of plastics in 7 Special Areas of Conservation ... more We investigated the concentration and composition of plastics in 7 Special Areas of Conservation (SACs) from the Gulf of Venice (northern Adriatic Sea). A total of 42 sediment samples were analyzed from 21 sites from 2017 to 2018. All sites except one were found to be polluted by plastics, with density ranging between 2250 and 28.4 items kg−1. Microplastics ranged from 100 to 61.6% of the collected plastics. Fragments were more represented than filaments. The greatest plastic concentrations were generally recorded in western SACs. Identification through FT-IR spectroscopy evidenced the presence of 8 polymer types: in western SACS, the majority were low-density polymers (PE, PP, PS, and TPU), while in eastern SACs they were high-density polymers (PET, nylon, and PVC). In addition to the role of large rivers (all on the western side of the Gulf) in conveying plastics into the sea, a possible role of the cyclonic water circulation of the northern Adriatic Sea on distribution and compos...
This is the first survey to investigate the occurrence and extent of plastic contamination in sed... more This is the first survey to investigate the occurrence and extent of plastic contamination in sediments collected in Terra Nova Bay (Ross Sea, Antarctica). Plastic debris extracted from 31 samples of sediments were counted, weighted and identified by Fourier-transform infrared spectroscopy (FT-IR). All sediment samples contained plastics: a total of 1661 items of debris (3.14g) were recorded from the 31 samples of sediment. Plastic particles in the samples ranged from 0.3 to 22mm in length. Fibres were the most frequent type of small plastics debris detected. In terms of abundance, microplastics (<5mm) accounted for 78.4% of debris. 9 polymer types were found: the most common material (94.13% by weight) was styrene-butadiene-styrene copolymer (SBS), widely used in pneumatic tires, etc. A decreasing concentration of plastic debris at increasing distances from the Mario Zucchelli Base was evidenced.
The aim of this study was to evaluate polyurethane percutaneous endoscopic gastrostomy (PEG) tube... more The aim of this study was to evaluate polyurethane percutaneous endoscopic gastrostomy (PEG) tube degradation and the role played by fungi. The inner surfaces of 20 used polyurethane tubes were brushed, and the brushing end was incubated for 7 days in Saburaud broth and cultured if fungal growth occurred. Three tubes used for 12 (sample 12w), 17 (sample 17w), and 96 (sample 96w) weeks and two new tubes were cut to produce several 4-cm-long equal halves. Six samples from the new tubes were considered control samples (Co sample), seven were incubated in Saburaud broth (Co sample + Sa.), and seven in the broth supplemented with Candida albicans (Co sample + Sa. + Ca). All samples underwent morphological examination by electron microscopy and differential scanning calorimetry measurements (DSC). All tubes had fungal colonization. DSC showed deterioration in all tubes including the new ones; adding Candida albicans had no additional effects. Morphological examination by electron microscopy showed a regular pattern in the Co sample, and thick biofilm, holes, and crevices in samples 12w, 17w, and 96w. The more the tubes had been used, the more severe were the changes. The Co sample + Sa and the Co sample + Sa + Ca showed no changes in the inner surface, but cryogenically fractured surfaces had holes and crevices. Yeasts constantly colonize PEG tubes and are likely to contribute to polyurethane deterioration. The impairment of new PEG tubes incubated in Saburaud broth suggests that other factors also play a role in polyurethane deterioration.
ABSTRACT A detailed re-examination of the photo-oxidation mechanism of poly(2,6-dimethyl-1,4-phen... more ABSTRACT A detailed re-examination of the photo-oxidation mechanism of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at both long and short irradiation wavelengths under accelerated conditions is reported. The formation rate of polydimethylphenoxy (PDMP) radicals is observed both in the presence and in the absence of ultra-violet (u.v.) light by using electron spin resonance spectroscopy. In order to explain the great stability of PDMP radicals, the bimolecular decay observed in the dark is discussed. In addition, spin-trapping experiments using nitrosodurene reveal the existence of benzylic-type radicals under u.v. irradiation conditions. Under mild oxidative conditions, i.e. thermo-oxidation at 80°C, the changes in the Fourier-transform infra-red spectra after 1215 h show the formation of two main absorption bands at 1694 and 1658 cm−1, assigned to aromatic aldehydes and quinonic groups, respectively. The poor photo-stability of these two primary oxidation products generates, by fast photolytic conversion to benzoic acids and esters. a broad band centred at 1734 cm−1 under accelerated photo-oxidative conditions. Furthermore, the cyclic voltammetry of PPO solution in the dark indicates both the existence of superoxide radical anions in the absence of u.v. light and the electro-catalytic effect possibly induced by quinonic groups. In this work direct formation of radical cations and superoxide anions by a photo-induced electron-transfer reaction is suggested under photo-oxidative conditions. The catalytic role of quinonic groups on the further generation of superoxide anions and PDMP radicals at long irradiation wavelengths and in the dark is also considered on the overall PPO photodegradation.
Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determ... more Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determine the concentrations of the two components of hindered amine light stabilisers (HALS) in low density polyethylene (LDPE) ®lms exposed to natural weathering up to 650 days. The used HALS is a Ciba-Geigy commercial mixture of Chimassorb 944 and Tinuvin 622 with same percentage in weight (50/50% (wt/wt)). The spectroscopic measurements were carried out on the LDPE ®lms having some different HALS contents of 0.1, 0.2, 0.4, and 0.6% (wt/wt). The Chimassorb 944 concentration was determined by means of the absorption band area centred at 225 nm in UV spectra for the absorption of 1,3,5-triazine group, while Tinuvin 622 concentration was measured by the absorption band area at 1734 cm 21 in FTIR spectra corresponding to the ester group absorption. The plots describing the loss of the concentration of each component versus time exhibited similar pro®les. The results suggest that the two HALS components are involved at the same time in the polymer stabilisation processes. The effect of the HALS concentration on LDPE stabilisation was interpreted applying the well-known operative mechanisms involving piperidinoxyl radicals for natural and accelerated photo-oxidative conditions. Finally electron spin resonance spectroscopy performed on 0.6 and 0.2% under natural exposure formulations are in good agreement with the spectroscopic determination of the HALS contents in the different formulations. q
Photodegradable polyolefins based on ketone carbonyl and carbon monoxide copolymers are discussed... more Photodegradable polyolefins based on ketone carbonyl and carbon monoxide copolymers are discussed. The proposed photooxidation mechanisms for these copolymers show efficient chain scission processes photoinduced by Norrish I and II reaction in polymer matrix. Other polyolefins copolymers containing unsaturation have been suggested as new innovative and photodegradable materials. In the photo-oxidative conditions, the formation of c@-unsaturated ketone impart high yields of chains scissions leading to a rapid embrittlement and fragmentation of these copolymers.
Spectrochimica Acta Part A: Molecular Spectroscopy, 1987
Raman and i.r. spectra of 1,l'diphenylethene and the low-frequency spectra of benzophenone, diphe... more Raman and i.r. spectra of 1,l'diphenylethene and the low-frequency spectra of benzophenone, diphenylketimine, diphenylmethane and diphenylether have been reinvestigated in order to attain a consistent attribution of the characteristic vibrations of geminal diphenyl substitution. Most of the internal vibrations of the benzene rings were seen in pairs of bands with very close frequencies, corresponding to symmetric (in-phase) and asymmetric (out-of-phase) modes. Of those monosubstituted-benzene vibrations usually considered to be sensitive to substitution, v,s, vs, and vIeb were found to span a narrow frequency interval, with a separation of l&20 cm-r between the respective symmetric and asymmetric modes. On the contrary, quite far apart frequencies were attributed to the symmetric and asymmetric modes of the vrbrattons vr, vgb and vIot,; for these, frequency separations ranging from about 50 to 140 cm-' were found, with a pronounced dependence of the covered spectral interval on the nature of the central group. The presence of a very strong Raman band at 9&80 cm-' was the most striking spectral characteristic for all of the molecules under consideration: it was attributed to the Ph-X-Ph angle bending vibration, although considerable mixing of it with other low-frequency vibrations was considered likely. Based on internal potential energy functions computed by a semikmp&al method (C-INDO), an approximate calculation of the frequencies for the conrotatory torsion of Ph,CCH,, Ph,CO and Ph,O and both torsions of Ph,CH, & was performed, so as to predict their relative magnitude&d t-0 assist the interpretation of the spectra in the lowest region. 1.r. bands observed at 55 and 70 cm-1 for Ph20 and Ph*CO, respectively, might be considered for assignment to torsional vibrations.
Journal of the Chemical Society, Faraday Transactions 2, 1988
... Marco Scoponi, Enzo Gallinella and Fabio Momicchioli" Dipartimento di Chimica, Universit... more ... Marco Scoponi, Enzo Gallinella and Fabio Momicchioli" Dipartimento di Chimica, Universita di Modena, I41 100 Modena, Italy ... Phys., 1980, 51, 113; (b) G. Bartocci, F.Masetti, U. Mazzucato and G. Marconi, J. Chem. Soc., Faraday Trans. ...
Journal of the Chemical Society, Perkin Transactions 2, 1991
ABSTRACT The crystal structure, and a complete vibrational analysis by FTIR and Raman spectra, of... more ABSTRACT The crystal structure, and a complete vibrational analysis by FTIR and Raman spectra, of guanylurea hydrochloride are presented. The crystallographic results show a pronounced π-electron delocalization on the cation and the presence of strong intra- and inter-molecular hydrogen bonding interactions between amino groups belonging to the guanidine moiety and the carbonyl oxygen of the ureic group. This arrangement gives rise to a polymer-like structure, in which the guanylurea cation chains are laterally hydrogen bonded by Cl– anions and water molecules. The UV–VlS reflectance spectra are in agreement with the hypothesis of the existence of hydrogen bonding charge transfer complexes in the solid state. Other spectroscopic techniques, such as FTIR and Raman, have been employed to support the crystal data, and to investigate the vibrational assignments for this compound.
The diffusion of a thermal stabiliser, Irganox 1010, has been studied both in a commercially avai... more The diffusion of a thermal stabiliser, Irganox 1010, has been studied both in a commercially available polypropylene homopolymer (HomoQ) and in a poly(propylene-co-ethylene) copolymer (RacoS). The diffusion experiments were carried out by using the Roe method formed by a stack of several polymer films having 60-70 mm as thickness under nitrogen atmosphere. The concentration profile of stabiliser in every film has been monitored by the absorbance at 282 nm in UV spectra recorded for every film forming the stack assembly. Under our experimental conditions, the diffusion of Irganox 1010 in each film stack for both polymer materials can be correctly interpreted by using the Fick's second law. The best fit of the experimental data with this equation allows calculation of the diffusion coefficients, D, for these polymer materials at 40, 70 and 80 C. By applying an Arrhenius equation to the calculated D coefficients, an estimation of activation energies of the diffusion process has been also achieved. #
Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determ... more Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determine the concentrations of the two components of hindered amine light stabilisers (HALS) in low density polyethylene (LDPE) ®lms exposed to natural weathering up to 650 days. The used HALS is a Ciba-Geigy commercial mixture of Chimassorb 944 and Tinuvin 622 with same percentage in weight (50/50% (wt/wt)). The spectroscopic measurements were carried out on the LDPE ®lms having some different HALS contents of 0.1, 0.2, 0.4, and 0.6% (wt/wt). The Chimassorb 944 concentration was determined by means of the absorption band area centred at 225 nm in UV spectra for the absorption of 1,3,5-triazine group, while Tinuvin 622 concentration was measured by the absorption band area at 1734 cm 21 in FTIR spectra corresponding to the ester group absorption. The plots describing the loss of the concentration of each component versus time exhibited similar pro®les. The results suggest that the two HALS components are involved at the same time in the polymer stabilisation processes. The effect of the HALS concentration on LDPE stabilisation was interpreted applying the well-known operative mechanisms involving piperidinoxyl radicals for natural and accelerated photo-oxidative conditions. Finally electron spin resonance spectroscopy performed on 0.6 and 0.2% under natural exposure formulations are in good agreement with the spectroscopic determination of the HALS contents in the different formulations. q
We investigated the concentration and composition of plastics in 7 Special Areas of Conservation ... more We investigated the concentration and composition of plastics in 7 Special Areas of Conservation (SACs) from the Gulf of Venice (northern Adriatic Sea). A total of 42 sediment samples were analyzed from 21 sites from 2017 to 2018. All sites except one were found to be polluted by plastics, with density ranging between 2250 and 28.4 items kg−1. Microplastics ranged from 100 to 61.6% of the collected plastics. Fragments were more represented than filaments. The greatest plastic concentrations were generally recorded in western SACs. Identification through FT-IR spectroscopy evidenced the presence of 8 polymer types: in western SACS, the majority were low-density polymers (PE, PP, PS, and TPU), while in eastern SACs they were high-density polymers (PET, nylon, and PVC). In addition to the role of large rivers (all on the western side of the Gulf) in conveying plastics into the sea, a possible role of the cyclonic water circulation of the northern Adriatic Sea on distribution and compos...
This is the first survey to investigate the occurrence and extent of plastic contamination in sed... more This is the first survey to investigate the occurrence and extent of plastic contamination in sediments collected in Terra Nova Bay (Ross Sea, Antarctica). Plastic debris extracted from 31 samples of sediments were counted, weighted and identified by Fourier-transform infrared spectroscopy (FT-IR). All sediment samples contained plastics: a total of 1661 items of debris (3.14g) were recorded from the 31 samples of sediment. Plastic particles in the samples ranged from 0.3 to 22mm in length. Fibres were the most frequent type of small plastics debris detected. In terms of abundance, microplastics (<5mm) accounted for 78.4% of debris. 9 polymer types were found: the most common material (94.13% by weight) was styrene-butadiene-styrene copolymer (SBS), widely used in pneumatic tires, etc. A decreasing concentration of plastic debris at increasing distances from the Mario Zucchelli Base was evidenced.
The aim of this study was to evaluate polyurethane percutaneous endoscopic gastrostomy (PEG) tube... more The aim of this study was to evaluate polyurethane percutaneous endoscopic gastrostomy (PEG) tube degradation and the role played by fungi. The inner surfaces of 20 used polyurethane tubes were brushed, and the brushing end was incubated for 7 days in Saburaud broth and cultured if fungal growth occurred. Three tubes used for 12 (sample 12w), 17 (sample 17w), and 96 (sample 96w) weeks and two new tubes were cut to produce several 4-cm-long equal halves. Six samples from the new tubes were considered control samples (Co sample), seven were incubated in Saburaud broth (Co sample + Sa.), and seven in the broth supplemented with Candida albicans (Co sample + Sa. + Ca). All samples underwent morphological examination by electron microscopy and differential scanning calorimetry measurements (DSC). All tubes had fungal colonization. DSC showed deterioration in all tubes including the new ones; adding Candida albicans had no additional effects. Morphological examination by electron microscopy showed a regular pattern in the Co sample, and thick biofilm, holes, and crevices in samples 12w, 17w, and 96w. The more the tubes had been used, the more severe were the changes. The Co sample + Sa and the Co sample + Sa + Ca showed no changes in the inner surface, but cryogenically fractured surfaces had holes and crevices. Yeasts constantly colonize PEG tubes and are likely to contribute to polyurethane deterioration. The impairment of new PEG tubes incubated in Saburaud broth suggests that other factors also play a role in polyurethane deterioration.
ABSTRACT A detailed re-examination of the photo-oxidation mechanism of poly(2,6-dimethyl-1,4-phen... more ABSTRACT A detailed re-examination of the photo-oxidation mechanism of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at both long and short irradiation wavelengths under accelerated conditions is reported. The formation rate of polydimethylphenoxy (PDMP) radicals is observed both in the presence and in the absence of ultra-violet (u.v.) light by using electron spin resonance spectroscopy. In order to explain the great stability of PDMP radicals, the bimolecular decay observed in the dark is discussed. In addition, spin-trapping experiments using nitrosodurene reveal the existence of benzylic-type radicals under u.v. irradiation conditions. Under mild oxidative conditions, i.e. thermo-oxidation at 80°C, the changes in the Fourier-transform infra-red spectra after 1215 h show the formation of two main absorption bands at 1694 and 1658 cm−1, assigned to aromatic aldehydes and quinonic groups, respectively. The poor photo-stability of these two primary oxidation products generates, by fast photolytic conversion to benzoic acids and esters. a broad band centred at 1734 cm−1 under accelerated photo-oxidative conditions. Furthermore, the cyclic voltammetry of PPO solution in the dark indicates both the existence of superoxide radical anions in the absence of u.v. light and the electro-catalytic effect possibly induced by quinonic groups. In this work direct formation of radical cations and superoxide anions by a photo-induced electron-transfer reaction is suggested under photo-oxidative conditions. The catalytic role of quinonic groups on the further generation of superoxide anions and PDMP radicals at long irradiation wavelengths and in the dark is also considered on the overall PPO photodegradation.
Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determ... more Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determine the concentrations of the two components of hindered amine light stabilisers (HALS) in low density polyethylene (LDPE) ®lms exposed to natural weathering up to 650 days. The used HALS is a Ciba-Geigy commercial mixture of Chimassorb 944 and Tinuvin 622 with same percentage in weight (50/50% (wt/wt)). The spectroscopic measurements were carried out on the LDPE ®lms having some different HALS contents of 0.1, 0.2, 0.4, and 0.6% (wt/wt). The Chimassorb 944 concentration was determined by means of the absorption band area centred at 225 nm in UV spectra for the absorption of 1,3,5-triazine group, while Tinuvin 622 concentration was measured by the absorption band area at 1734 cm 21 in FTIR spectra corresponding to the ester group absorption. The plots describing the loss of the concentration of each component versus time exhibited similar pro®les. The results suggest that the two HALS components are involved at the same time in the polymer stabilisation processes. The effect of the HALS concentration on LDPE stabilisation was interpreted applying the well-known operative mechanisms involving piperidinoxyl radicals for natural and accelerated photo-oxidative conditions. Finally electron spin resonance spectroscopy performed on 0.6 and 0.2% under natural exposure formulations are in good agreement with the spectroscopic determination of the HALS contents in the different formulations. q
Photodegradable polyolefins based on ketone carbonyl and carbon monoxide copolymers are discussed... more Photodegradable polyolefins based on ketone carbonyl and carbon monoxide copolymers are discussed. The proposed photooxidation mechanisms for these copolymers show efficient chain scission processes photoinduced by Norrish I and II reaction in polymer matrix. Other polyolefins copolymers containing unsaturation have been suggested as new innovative and photodegradable materials. In the photo-oxidative conditions, the formation of c@-unsaturated ketone impart high yields of chains scissions leading to a rapid embrittlement and fragmentation of these copolymers.
Spectrochimica Acta Part A: Molecular Spectroscopy, 1987
Raman and i.r. spectra of 1,l'diphenylethene and the low-frequency spectra of benzophenone, diphe... more Raman and i.r. spectra of 1,l'diphenylethene and the low-frequency spectra of benzophenone, diphenylketimine, diphenylmethane and diphenylether have been reinvestigated in order to attain a consistent attribution of the characteristic vibrations of geminal diphenyl substitution. Most of the internal vibrations of the benzene rings were seen in pairs of bands with very close frequencies, corresponding to symmetric (in-phase) and asymmetric (out-of-phase) modes. Of those monosubstituted-benzene vibrations usually considered to be sensitive to substitution, v,s, vs, and vIeb were found to span a narrow frequency interval, with a separation of l&20 cm-r between the respective symmetric and asymmetric modes. On the contrary, quite far apart frequencies were attributed to the symmetric and asymmetric modes of the vrbrattons vr, vgb and vIot,; for these, frequency separations ranging from about 50 to 140 cm-' were found, with a pronounced dependence of the covered spectral interval on the nature of the central group. The presence of a very strong Raman band at 9&80 cm-' was the most striking spectral characteristic for all of the molecules under consideration: it was attributed to the Ph-X-Ph angle bending vibration, although considerable mixing of it with other low-frequency vibrations was considered likely. Based on internal potential energy functions computed by a semikmp&al method (C-INDO), an approximate calculation of the frequencies for the conrotatory torsion of Ph,CCH,, Ph,CO and Ph,O and both torsions of Ph,CH, & was performed, so as to predict their relative magnitude&d t-0 assist the interpretation of the spectra in the lowest region. 1.r. bands observed at 55 and 70 cm-1 for Ph20 and Ph*CO, respectively, might be considered for assignment to torsional vibrations.
Journal of the Chemical Society, Faraday Transactions 2, 1988
... Marco Scoponi, Enzo Gallinella and Fabio Momicchioli" Dipartimento di Chimica, Universit... more ... Marco Scoponi, Enzo Gallinella and Fabio Momicchioli" Dipartimento di Chimica, Universita di Modena, I41 100 Modena, Italy ... Phys., 1980, 51, 113; (b) G. Bartocci, F.Masetti, U. Mazzucato and G. Marconi, J. Chem. Soc., Faraday Trans. ...
Journal of the Chemical Society, Perkin Transactions 2, 1991
ABSTRACT The crystal structure, and a complete vibrational analysis by FTIR and Raman spectra, of... more ABSTRACT The crystal structure, and a complete vibrational analysis by FTIR and Raman spectra, of guanylurea hydrochloride are presented. The crystallographic results show a pronounced π-electron delocalization on the cation and the presence of strong intra- and inter-molecular hydrogen bonding interactions between amino groups belonging to the guanidine moiety and the carbonyl oxygen of the ureic group. This arrangement gives rise to a polymer-like structure, in which the guanylurea cation chains are laterally hydrogen bonded by Cl– anions and water molecules. The UV–VlS reflectance spectra are in agreement with the hypothesis of the existence of hydrogen bonding charge transfer complexes in the solid state. Other spectroscopic techniques, such as FTIR and Raman, have been employed to support the crystal data, and to investigate the vibrational assignments for this compound.
The diffusion of a thermal stabiliser, Irganox 1010, has been studied both in a commercially avai... more The diffusion of a thermal stabiliser, Irganox 1010, has been studied both in a commercially available polypropylene homopolymer (HomoQ) and in a poly(propylene-co-ethylene) copolymer (RacoS). The diffusion experiments were carried out by using the Roe method formed by a stack of several polymer films having 60-70 mm as thickness under nitrogen atmosphere. The concentration profile of stabiliser in every film has been monitored by the absorbance at 282 nm in UV spectra recorded for every film forming the stack assembly. Under our experimental conditions, the diffusion of Irganox 1010 in each film stack for both polymer materials can be correctly interpreted by using the Fick's second law. The best fit of the experimental data with this equation allows calculation of the diffusion coefficients, D, for these polymer materials at 40, 70 and 80 C. By applying an Arrhenius equation to the calculated D coefficients, an estimation of activation energies of the diffusion process has been also achieved. #
Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determ... more Spectroscopic methods, ultraviolet (UV) and Fourier transform infrared (FTIR) were used to determine the concentrations of the two components of hindered amine light stabilisers (HALS) in low density polyethylene (LDPE) ®lms exposed to natural weathering up to 650 days. The used HALS is a Ciba-Geigy commercial mixture of Chimassorb 944 and Tinuvin 622 with same percentage in weight (50/50% (wt/wt)). The spectroscopic measurements were carried out on the LDPE ®lms having some different HALS contents of 0.1, 0.2, 0.4, and 0.6% (wt/wt). The Chimassorb 944 concentration was determined by means of the absorption band area centred at 225 nm in UV spectra for the absorption of 1,3,5-triazine group, while Tinuvin 622 concentration was measured by the absorption band area at 1734 cm 21 in FTIR spectra corresponding to the ester group absorption. The plots describing the loss of the concentration of each component versus time exhibited similar pro®les. The results suggest that the two HALS components are involved at the same time in the polymer stabilisation processes. The effect of the HALS concentration on LDPE stabilisation was interpreted applying the well-known operative mechanisms involving piperidinoxyl radicals for natural and accelerated photo-oxidative conditions. Finally electron spin resonance spectroscopy performed on 0.6 and 0.2% under natural exposure formulations are in good agreement with the spectroscopic determination of the HALS contents in the different formulations. q
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