Oscar Chiantore | Università degli Studi di Torino (original) (raw)

Papers by Oscar Chiantore

Research paper thumbnail of Comparison between off-line and on-line derivatisation methods in the characterisation of siccative oils in paint media

Journal of analytical and applied …, Jan 1, 2005

The characterisation of siccative oils (drying oils used in paint media) by gas-chromatography/ma... more The characterisation of siccative oils (drying oils used in paint media) by gas-chromatography/mass-spectrometry using three derivatisation methods has been investigated and the differences in results discussed. The classic off-line derivatisation method with ( ...

Research paper thumbnail of Historical conservation treatments in palaeontology: the geo-palaeontological collection of the Geology and Palaeontology Museum of the University of Turin managed by the Piedmont Council Museum of Natural Science of Turin

The change of environmental conditions following the discovery of fossils and mechanical stresses... more The change of environmental conditions following the discovery of fossils and mechanical stresses during the excavation phase can raise the already grave fragility of the findings. As a consequence, fractures, detachments and powdering phenomena can appear and a conservation treatment is required to restore the objects and preserve them from further degradation. Traditionally, scientists have been using products of natural origin (animal glues, resins or gums) as consolidants and adhesives, but in the course of the last century these materials have been often replaced by synthetic products. In this survey part of the geopalaeontological collection of the Geology and Palaeontology Museum of the University of Turin managed by the Piedmont Council Museum of Natural Sciences in Turin has been evaluated by considering the efficacy of the consolidation treatments and the products employed over the years.

Research paper thumbnail of Fluorinated polymeric materials for the protection of monumental buildings

Macromolecular Symposia, 2000

Research paper thumbnail of Evidence of random chain scissions at low temperatures in the thermal degradation of anionic polystyrenes

Polymer Degradation and Stability, 1985

Research paper thumbnail of Refractive index of poly(thiocarbonate)s and poly(dithiocarbonate)s

Polymer, 1994

The refractive indices and densities of recently synthesized poly(thiocarbonate)s and poly(dithio... more The refractive indices and densities of recently synthesized poly(thiocarbonate)s and poly(dithiocarbonate)s were measured, and were used to determine the group contributions of thiocarbonate (-O-CO-S-) and dithiocarbonate (-S-CO S-) groups to the molar refraction. The high refractive indices observed make these polymers, particularly the poly(dithiocarbonate)s, potentially interesting for optical applications (i.e. lenses and optical fibres).

Research paper thumbnail of Monte Carlo simulations of polymer degradations. 1. Degradations without volatilization

Research paper thumbnail of Ageing behaviour and analytical pyrolysis characterisation of diterpenic resins used as art materials: Manila copal and sandarac

Journal of Analytical and Applied Pyrolysis, 2003

ABSTRACT Artificial indoor and outdoor exposure conditions have been applied in order to investig... more ABSTRACT Artificial indoor and outdoor exposure conditions have been applied in order to investigate the photo-ageing behaviour of two natural resins once used as art materials. Copals and sandarac consist of free labdane diterpenoids and of a highly cross-linked fraction of polycommunic acid. To determine the nature and the composition of the cross-linked fraction, pyrolysis is required. Thermally assisted hydrolysis and methylation, coupled with gas chromatography–mass spectrometry (THM-GC/MS), has been used to identify the acidic compounds. Many secondary pyrolysis products have been recognised and distinguished from the original resin components. Further details on the composition and ageing behaviour of Manila copal and sandarac have been obtained from Fourier transform infrared spectroscopy (FTIR), size exclusion chromatography (SEC) and direct temperature-resolved mass spectrometry (DTMS). During ageing, cross-linking and cleavage reactions were found to affect largely the chemical structure of the two resins, together with minor degradation processes such as isomerisation, defunctionalisation and oxidation.

Research paper thumbnail of An initial assessment of thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry for the identification of oils from dried paint films

Journal of Analytical and Applied Pyrolysis, 2002

Conservation scientists are frequently asked to identify the materials that are contained in micr... more Conservation scientists are frequently asked to identify the materials that are contained in microscopic fragments from works of art. For decades, the only technique successfully used for characterising the type of oil binder used from dried oil paints has been gas chromatography/mass spectrometry (GCMS). Unfortunately, the process requires a lengthy sample preparation and some of the derivatisation processes used present serious health and safety implications. Although thermally assisted hydrolysis and methylation-GCMS (THM-GCMS) has been used more recently for the analysis of traditional paint binders, its ability to distinguish between different oil types has yet to be ascertained. This paper describes the use of THM-GCMS to examine differences in the fatty acid composition of dried pigmented films of linseed, linseed stand, poppy, safflower and walnut oil. The results were compared for pyrolysis at 610 and 770°C, two of the most commonly used temperatures in Curie point pyrolysis, in order to verify reproducibility of the results. Based on three runs for each sample, the fatty acid composition (measured as methyl esters) was found to be temperaturedependent, as previously suggested in literature. At the lower pyrolysis temperature (610°C), a higher degree of reproducibility was seen and the ability to differentiate between each of the dried oil types using palmitate/stearate (P/S) ratios was improved. Interestingly, the P/S observed for each oil at this pyrolysis temperature were found to be close to those obtained by published GCMS procedures. In addition, samples of dried pigmented films of egg yolk were investigated and it was confirmed that this medium could be differentiated from each : S 0 1 6 5 -2 3 7 0 ( 0 1 ) 0 0 1 6 4 -4 340 F. Cappitelli et al. / J. Anal. Appl. Pyrolysis 63 (2002) 339-348 of the drying oils at this pyrolysis temperature from their azelate/palmitate ratios. These preliminary findings are encouraging for the use of THM-GCMS as an alternative method to GCMS for the identification of oils used as binders in paints.

Research paper thumbnail of Thermal degradation of model linear and star-shaped polyisoprene molecules

Polymer Degradation and Stability, 1995

The thermal degradation behavior, in the absence of air, of model star-shaped and linear polyisop... more The thermal degradation behavior, in the absence of air, of model star-shaped and linear polyisoprenes with silyl alkyl groups, prepared using anionic polymerization techniques and chlorosilanes as linking agents, has been investigated and compared with that of model linear polyisoprenes. Thermal stabilities were examined by thermogravimetry and differential scanning calorimetry, while analysis of degradation products and of polymer residues obtained

Research paper thumbnail of Thermally assisted hydrolysis and methylation-pyrolysis-gas chromatography/mass spectrometry of light-aged linseed oil

Journal of Analytical and Applied Pyrolysis, 2001

In this paper we applied thermally assisted hydrolysis and methylation to a soil humic acid (HA) ... more In this paper we applied thermally assisted hydrolysis and methylation to a soil humic acid (HA) and their polyacrylamide gel electrophoresis (PAGE) fractions. The data indicates that PAGE fractionation of HA produces selectively enriched humic fractions in terms of major structural components (e.g. fatty acids, lignin units, etc.). Lignin components were mainly found in fraction b (medium electrophoretic mobility) of HA. Plant fatty acids were mainly distributed in fraction a (no electrophoretic mobility), and microbial lipids were distributed in all fractions, but the higher relative amounts appeared primarily associated with fractions b and c+ d (high electrophoretic mobility).

Research paper thumbnail of Structure control, coating properties, and durability of fluorinated acrylic-based polymers

Journal of Coatings Technology, 2002

Fluorinated acrylates were employed for the synthesis of conventional, side-chain fluorinated, fu... more Fluorinated acrylates were employed for the synthesis of conventional, side-chain fluorinated, fully acrylic random copolymers, and of more unusual hybrid copolymers with vinyl ethers. The latter can feature alternating structure and peculiar material properties associated with fluorine or fluorinated groups substitution onto the polymer backbone. Improved efficacy and durability of the resulting coating, highly desirable for the consolidation and protection of highly valued works of art, was achieved through a systematic approach involving a detailed study of their photodegradation behavior, and extensive testing of protection efficacy upon application onto micro-and macroporous stone substrates of different chemical composition and morphology.

Research paper thumbnail of Characterization of Acrylic Resins

International Journal of Polymer Analysis and Characterization, 1996

ABSTRACT Selected samples of commercial acrylic resins used for protection and consolidation of d... more ABSTRACT Selected samples of commercial acrylic resins used for protection and consolidation of different substrates have been characterized in terms of their chemical structures and compositions. Resin compositions were determined from analysis of the products obtained under controlled thermal decomposition of the samples, whereas the amounts of different components were established by NMR spectroscopy. Several resins were formed by two different structural units, whereas the others contain a third component, although in low quantities. The elution behavior of the samples in adsorption liquid chromatography confirmed that the two-component resins are binary random copolymers. As to the ternary samples, it appears that they are either ternary copolymers or mixtures of two different binary copolymers having one monomeric unit in common. It is also shown that the different protective acrylic resins may be distinguished by their refractive indexes and thermogravimetric behavior.

Research paper thumbnail of Photochemical stability of partially fluorinated acrylic protective coatings I. Poly(2,2,2-trifluoroethyl methacrylate) and poly(1H,1H,2H,2H-perfluorodecyl methacrylate- co-2-ethylhexyl methacrylate)s

Polymer Degradation and Stability, 2000

The photochemical stability and photodegradation pathways of poly(2,2,2-tri¯uoroethyl methacrylat... more The photochemical stability and photodegradation pathways of poly(2,2,2-tri¯uoroethyl methacrylate) (PTFEMA) and copolymers of 1H,1H,2H,2H-per¯uorodecyl methacrylate with 2-ethylhexyl methacrylate (XFDMA±EHMA) have been investigated under arti®cial solar light irradiation. The extent of degradation was assessed by weight loss and gel content determination, size exclusion chromatography and FTIR spectroscopy. PTFEMA exposed up to 2000 h showed only molecular changes due to a low extent of chain scission. The two XFDMA±EHMA copolymers underwent much more degradation, with extensive cross-linking, formation of low-molecular weight products, and oxidation reactions on the chains. The behaviour of the copolymers is controlled by the reactivity of the EHMA units, as was shown by comparison with results obtained on degradation of PEHMA homopolymer. #

Research paper thumbnail of Photochemical stability of partially fluorinated acrylic protective coatings IV. Copolymers of 2,2,2-trifluoroethyl methacrylate and methyl α-trifluoromethyl acrylate with vinyl ethers

Polymer Degradation and Stability, 2003

The photochemical stability and photodegradation pathways of poly(2,2,2-tri¯uoroethyl methacrylat... more The photochemical stability and photodegradation pathways of poly(2,2,2-tri¯uoroethyl methacrylate) (PTFEMA) and copolymers of 1H,1H,2H,2H-per¯uorodecyl methacrylate with 2-ethylhexyl methacrylate (XFDMA±EHMA) have been investigated under arti®cial solar light irradiation. The extent of degradation was assessed by weight loss and gel content determination, size exclusion chromatography and FTIR spectroscopy. PTFEMA exposed up to 2000 h showed only molecular changes due to a low extent of chain scission. The two XFDMA±EHMA copolymers underwent much more degradation, with extensive cross-linking, formation of low-molecular weight products, and oxidation reactions on the chains. The behaviour of the copolymers is controlled by the reactivity of the EHMA units, as was shown by comparison with results obtained on degradation of PEHMA homopolymer. #

Research paper thumbnail of Ageing behaviour and pyrolytic characterisation of diterpenic resins used as art materials: colophony and Venice turpentine

Journal of Analytical and Applied Pyrolysis, 2002

The ageing behaviour of two diterpenic resins traditionally used as artists' materials, colophony... more The ageing behaviour of two diterpenic resins traditionally used as artists' materials, colophony and Venice turpentine, was investigated with different spectroscopic and chromatographic techniques. In particular, three types of ageing (natural, artificial external conditions with a xenon lamp, artificial indoor conditions with fluorescent tubes) were applied to laboratory samples to study their effects on chemical structures. Thermally-assisted hydrolysis and methylation-gas chromatography-mass spectrometry (THM-GC/MS) was employed for careful characterisation and for identification of markers compounds on the vergin resins and in the course of ageing. The most significant changes were detected in the initial part of ageing, and the principal degradation products coming from oxidation, polymerisation and cleavage reactions identified. The high intensity of xenon lamp irradiation was found to cause, apart from oxidation and polymerisation reactions, further degradation of the chemical structure with molecular fragmentation. From the analytical point of view, the differentiation between colophony and Venice turpentine with THM-GC/MS appears to depend on differences in the lower molecular weight resin components.

Research paper thumbnail of Photo-oxidative stability of paraloid acrylic protective polymers

Polymer, 2001

The photo-oxidative stability of a series of commercial acrylic/methacrylic protective resins, wh... more The photo-oxidative stability of a series of commercial acrylic/methacrylic protective resins, which find use in consolidation and protection of art works, monuments and historical buildings, and are known by the name of Paraloids, has been investigated. The structural and molecular changes occurring under conditions of artificial solar light irradiation have been followed by FTIR and UV-Vis spectroscopy, and size exclusion chromatography. In all the resins the first degradative event which is detected is the molecular weight distribution change due to chain scissions and/or coupling of macroradicals. The overall stability of the polymers is strongly influenced by the presence of long alkyl side groups, such as butyl or isobutyl, whose oxidation is favoured by the presence of relatively labile hydrogen atoms. At the same time these polymers containing long ester groups undergo fast and extensive cross-linking together with some fragmentation and consequent weight losses. The resins containing only ethyl and methyl esters showed a good stability towards oxidation, reaching an equilibrium between scission reactions and macromolecular coupling which permit them to maintain their molecular characteristics during the ageing. ᭧

Research paper thumbnail of Synthesis of Polyacrylonitrile-block-Polystyrene Copolymers by Atom Transfer Radical Polymerization

Macromolecular Chemistry and Physics, 2005

Research paper thumbnail of Drying and oxidative degradation of linseed oil

Polymer Degradation and Stability, 1999

... Ltd. All rights reserved. Permissions & Reprints. Drying and oxidative de... more ... Ltd. All rights reserved. Permissions & Reprints. Drying and oxidative degradation of linseed oil. Massimo Lazzari and Oscar Chiantore Corresponding Author Contact Information , E-mail The Corresponding Author. Department ...

Research paper thumbnail of Photodegradation of acrylic resins used in the conservation of stone

Polymer Degradation and Stability, 1999

The photodegradative behaviour of a series of ®lms of acrylic resins, under controlled conditions... more The photodegradative behaviour of a series of ®lms of acrylic resins, under controlled conditions (RH=50% and T=25 C) has been studied. Films of acrylic resins were applied both on a dolomitic white marble support and on potassium bromide disks. The chemical evolution of the system has been followed by means of FT±IR spectra, HPLC±SEC, colour and water absorption measurements. The main degradation pathway under ultraviolet irradiation is chain scission. The observed rates of photodegradation of the dierent resins may be related to the type of the ester group and to the presence of the a-methyl group in the main chain. # 1999 Elsevier Science Ltd. All rights reserved. 0141-3910/99/$ -see front matter # 1999 Elsevier Science Ltd. All rights reserved. P I I : S 0 1 4 1 -3 9 1 0 ( 9 9 ) 0 0 0 4 8 -8

Research paper thumbnail of Compatibilization effects in the thermal degradation of blends containing SAN and EPDM polymers

Polymer, 1998

ABSTRACT Thermal degradation of blends containing SAN and EPDM was investigated and compared with... more ABSTRACT Thermal degradation of blends containing SAN and EPDM was investigated and compared with that of graft EPDM-g-SAN copolymer molecules. Characterization of decomposition products and of degradation residues was carried out in order to reveal the differences in the degradation processes. With plain mixtures of SAN and EPDM, degradation behaviour is practically additive whereas in the case of EPDM-g-SAN lower volatile products and larger chain scissions are produced. The results can be explained by considering that the degradation process is influenced by the dispersion of the blend components. In phase segregated systems very few interactions take place between the different types of polymers, whereas in the graft copolymer molecular dispersion favours reactive interactions between the structurally different components.

Research paper thumbnail of Comparison between off-line and on-line derivatisation methods in the characterisation of siccative oils in paint media

Journal of analytical and applied …, Jan 1, 2005

The characterisation of siccative oils (drying oils used in paint media) by gas-chromatography/ma... more The characterisation of siccative oils (drying oils used in paint media) by gas-chromatography/mass-spectrometry using three derivatisation methods has been investigated and the differences in results discussed. The classic off-line derivatisation method with ( ...

Research paper thumbnail of Historical conservation treatments in palaeontology: the geo-palaeontological collection of the Geology and Palaeontology Museum of the University of Turin managed by the Piedmont Council Museum of Natural Science of Turin

The change of environmental conditions following the discovery of fossils and mechanical stresses... more The change of environmental conditions following the discovery of fossils and mechanical stresses during the excavation phase can raise the already grave fragility of the findings. As a consequence, fractures, detachments and powdering phenomena can appear and a conservation treatment is required to restore the objects and preserve them from further degradation. Traditionally, scientists have been using products of natural origin (animal glues, resins or gums) as consolidants and adhesives, but in the course of the last century these materials have been often replaced by synthetic products. In this survey part of the geopalaeontological collection of the Geology and Palaeontology Museum of the University of Turin managed by the Piedmont Council Museum of Natural Sciences in Turin has been evaluated by considering the efficacy of the consolidation treatments and the products employed over the years.

Research paper thumbnail of Fluorinated polymeric materials for the protection of monumental buildings

Macromolecular Symposia, 2000

Research paper thumbnail of Evidence of random chain scissions at low temperatures in the thermal degradation of anionic polystyrenes

Polymer Degradation and Stability, 1985

Research paper thumbnail of Refractive index of poly(thiocarbonate)s and poly(dithiocarbonate)s

Polymer, 1994

The refractive indices and densities of recently synthesized poly(thiocarbonate)s and poly(dithio... more The refractive indices and densities of recently synthesized poly(thiocarbonate)s and poly(dithiocarbonate)s were measured, and were used to determine the group contributions of thiocarbonate (-O-CO-S-) and dithiocarbonate (-S-CO S-) groups to the molar refraction. The high refractive indices observed make these polymers, particularly the poly(dithiocarbonate)s, potentially interesting for optical applications (i.e. lenses and optical fibres).

Research paper thumbnail of Monte Carlo simulations of polymer degradations. 1. Degradations without volatilization

Research paper thumbnail of Ageing behaviour and analytical pyrolysis characterisation of diterpenic resins used as art materials: Manila copal and sandarac

Journal of Analytical and Applied Pyrolysis, 2003

ABSTRACT Artificial indoor and outdoor exposure conditions have been applied in order to investig... more ABSTRACT Artificial indoor and outdoor exposure conditions have been applied in order to investigate the photo-ageing behaviour of two natural resins once used as art materials. Copals and sandarac consist of free labdane diterpenoids and of a highly cross-linked fraction of polycommunic acid. To determine the nature and the composition of the cross-linked fraction, pyrolysis is required. Thermally assisted hydrolysis and methylation, coupled with gas chromatography–mass spectrometry (THM-GC/MS), has been used to identify the acidic compounds. Many secondary pyrolysis products have been recognised and distinguished from the original resin components. Further details on the composition and ageing behaviour of Manila copal and sandarac have been obtained from Fourier transform infrared spectroscopy (FTIR), size exclusion chromatography (SEC) and direct temperature-resolved mass spectrometry (DTMS). During ageing, cross-linking and cleavage reactions were found to affect largely the chemical structure of the two resins, together with minor degradation processes such as isomerisation, defunctionalisation and oxidation.

Research paper thumbnail of An initial assessment of thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry for the identification of oils from dried paint films

Journal of Analytical and Applied Pyrolysis, 2002

Conservation scientists are frequently asked to identify the materials that are contained in micr... more Conservation scientists are frequently asked to identify the materials that are contained in microscopic fragments from works of art. For decades, the only technique successfully used for characterising the type of oil binder used from dried oil paints has been gas chromatography/mass spectrometry (GCMS). Unfortunately, the process requires a lengthy sample preparation and some of the derivatisation processes used present serious health and safety implications. Although thermally assisted hydrolysis and methylation-GCMS (THM-GCMS) has been used more recently for the analysis of traditional paint binders, its ability to distinguish between different oil types has yet to be ascertained. This paper describes the use of THM-GCMS to examine differences in the fatty acid composition of dried pigmented films of linseed, linseed stand, poppy, safflower and walnut oil. The results were compared for pyrolysis at 610 and 770°C, two of the most commonly used temperatures in Curie point pyrolysis, in order to verify reproducibility of the results. Based on three runs for each sample, the fatty acid composition (measured as methyl esters) was found to be temperaturedependent, as previously suggested in literature. At the lower pyrolysis temperature (610°C), a higher degree of reproducibility was seen and the ability to differentiate between each of the dried oil types using palmitate/stearate (P/S) ratios was improved. Interestingly, the P/S observed for each oil at this pyrolysis temperature were found to be close to those obtained by published GCMS procedures. In addition, samples of dried pigmented films of egg yolk were investigated and it was confirmed that this medium could be differentiated from each : S 0 1 6 5 -2 3 7 0 ( 0 1 ) 0 0 1 6 4 -4 340 F. Cappitelli et al. / J. Anal. Appl. Pyrolysis 63 (2002) 339-348 of the drying oils at this pyrolysis temperature from their azelate/palmitate ratios. These preliminary findings are encouraging for the use of THM-GCMS as an alternative method to GCMS for the identification of oils used as binders in paints.

Research paper thumbnail of Thermal degradation of model linear and star-shaped polyisoprene molecules

Polymer Degradation and Stability, 1995

The thermal degradation behavior, in the absence of air, of model star-shaped and linear polyisop... more The thermal degradation behavior, in the absence of air, of model star-shaped and linear polyisoprenes with silyl alkyl groups, prepared using anionic polymerization techniques and chlorosilanes as linking agents, has been investigated and compared with that of model linear polyisoprenes. Thermal stabilities were examined by thermogravimetry and differential scanning calorimetry, while analysis of degradation products and of polymer residues obtained

Research paper thumbnail of Thermally assisted hydrolysis and methylation-pyrolysis-gas chromatography/mass spectrometry of light-aged linseed oil

Journal of Analytical and Applied Pyrolysis, 2001

In this paper we applied thermally assisted hydrolysis and methylation to a soil humic acid (HA) ... more In this paper we applied thermally assisted hydrolysis and methylation to a soil humic acid (HA) and their polyacrylamide gel electrophoresis (PAGE) fractions. The data indicates that PAGE fractionation of HA produces selectively enriched humic fractions in terms of major structural components (e.g. fatty acids, lignin units, etc.). Lignin components were mainly found in fraction b (medium electrophoretic mobility) of HA. Plant fatty acids were mainly distributed in fraction a (no electrophoretic mobility), and microbial lipids were distributed in all fractions, but the higher relative amounts appeared primarily associated with fractions b and c+ d (high electrophoretic mobility).

Research paper thumbnail of Structure control, coating properties, and durability of fluorinated acrylic-based polymers

Journal of Coatings Technology, 2002

Fluorinated acrylates were employed for the synthesis of conventional, side-chain fluorinated, fu... more Fluorinated acrylates were employed for the synthesis of conventional, side-chain fluorinated, fully acrylic random copolymers, and of more unusual hybrid copolymers with vinyl ethers. The latter can feature alternating structure and peculiar material properties associated with fluorine or fluorinated groups substitution onto the polymer backbone. Improved efficacy and durability of the resulting coating, highly desirable for the consolidation and protection of highly valued works of art, was achieved through a systematic approach involving a detailed study of their photodegradation behavior, and extensive testing of protection efficacy upon application onto micro-and macroporous stone substrates of different chemical composition and morphology.

Research paper thumbnail of Characterization of Acrylic Resins

International Journal of Polymer Analysis and Characterization, 1996

ABSTRACT Selected samples of commercial acrylic resins used for protection and consolidation of d... more ABSTRACT Selected samples of commercial acrylic resins used for protection and consolidation of different substrates have been characterized in terms of their chemical structures and compositions. Resin compositions were determined from analysis of the products obtained under controlled thermal decomposition of the samples, whereas the amounts of different components were established by NMR spectroscopy. Several resins were formed by two different structural units, whereas the others contain a third component, although in low quantities. The elution behavior of the samples in adsorption liquid chromatography confirmed that the two-component resins are binary random copolymers. As to the ternary samples, it appears that they are either ternary copolymers or mixtures of two different binary copolymers having one monomeric unit in common. It is also shown that the different protective acrylic resins may be distinguished by their refractive indexes and thermogravimetric behavior.

Research paper thumbnail of Photochemical stability of partially fluorinated acrylic protective coatings I. Poly(2,2,2-trifluoroethyl methacrylate) and poly(1H,1H,2H,2H-perfluorodecyl methacrylate- co-2-ethylhexyl methacrylate)s

Polymer Degradation and Stability, 2000

The photochemical stability and photodegradation pathways of poly(2,2,2-tri¯uoroethyl methacrylat... more The photochemical stability and photodegradation pathways of poly(2,2,2-tri¯uoroethyl methacrylate) (PTFEMA) and copolymers of 1H,1H,2H,2H-per¯uorodecyl methacrylate with 2-ethylhexyl methacrylate (XFDMA±EHMA) have been investigated under arti®cial solar light irradiation. The extent of degradation was assessed by weight loss and gel content determination, size exclusion chromatography and FTIR spectroscopy. PTFEMA exposed up to 2000 h showed only molecular changes due to a low extent of chain scission. The two XFDMA±EHMA copolymers underwent much more degradation, with extensive cross-linking, formation of low-molecular weight products, and oxidation reactions on the chains. The behaviour of the copolymers is controlled by the reactivity of the EHMA units, as was shown by comparison with results obtained on degradation of PEHMA homopolymer. #

Research paper thumbnail of Photochemical stability of partially fluorinated acrylic protective coatings IV. Copolymers of 2,2,2-trifluoroethyl methacrylate and methyl α-trifluoromethyl acrylate with vinyl ethers

Polymer Degradation and Stability, 2003

The photochemical stability and photodegradation pathways of poly(2,2,2-tri¯uoroethyl methacrylat... more The photochemical stability and photodegradation pathways of poly(2,2,2-tri¯uoroethyl methacrylate) (PTFEMA) and copolymers of 1H,1H,2H,2H-per¯uorodecyl methacrylate with 2-ethylhexyl methacrylate (XFDMA±EHMA) have been investigated under arti®cial solar light irradiation. The extent of degradation was assessed by weight loss and gel content determination, size exclusion chromatography and FTIR spectroscopy. PTFEMA exposed up to 2000 h showed only molecular changes due to a low extent of chain scission. The two XFDMA±EHMA copolymers underwent much more degradation, with extensive cross-linking, formation of low-molecular weight products, and oxidation reactions on the chains. The behaviour of the copolymers is controlled by the reactivity of the EHMA units, as was shown by comparison with results obtained on degradation of PEHMA homopolymer. #

Research paper thumbnail of Ageing behaviour and pyrolytic characterisation of diterpenic resins used as art materials: colophony and Venice turpentine

Journal of Analytical and Applied Pyrolysis, 2002

The ageing behaviour of two diterpenic resins traditionally used as artists' materials, colophony... more The ageing behaviour of two diterpenic resins traditionally used as artists' materials, colophony and Venice turpentine, was investigated with different spectroscopic and chromatographic techniques. In particular, three types of ageing (natural, artificial external conditions with a xenon lamp, artificial indoor conditions with fluorescent tubes) were applied to laboratory samples to study their effects on chemical structures. Thermally-assisted hydrolysis and methylation-gas chromatography-mass spectrometry (THM-GC/MS) was employed for careful characterisation and for identification of markers compounds on the vergin resins and in the course of ageing. The most significant changes were detected in the initial part of ageing, and the principal degradation products coming from oxidation, polymerisation and cleavage reactions identified. The high intensity of xenon lamp irradiation was found to cause, apart from oxidation and polymerisation reactions, further degradation of the chemical structure with molecular fragmentation. From the analytical point of view, the differentiation between colophony and Venice turpentine with THM-GC/MS appears to depend on differences in the lower molecular weight resin components.

Research paper thumbnail of Photo-oxidative stability of paraloid acrylic protective polymers

Polymer, 2001

The photo-oxidative stability of a series of commercial acrylic/methacrylic protective resins, wh... more The photo-oxidative stability of a series of commercial acrylic/methacrylic protective resins, which find use in consolidation and protection of art works, monuments and historical buildings, and are known by the name of Paraloids, has been investigated. The structural and molecular changes occurring under conditions of artificial solar light irradiation have been followed by FTIR and UV-Vis spectroscopy, and size exclusion chromatography. In all the resins the first degradative event which is detected is the molecular weight distribution change due to chain scissions and/or coupling of macroradicals. The overall stability of the polymers is strongly influenced by the presence of long alkyl side groups, such as butyl or isobutyl, whose oxidation is favoured by the presence of relatively labile hydrogen atoms. At the same time these polymers containing long ester groups undergo fast and extensive cross-linking together with some fragmentation and consequent weight losses. The resins containing only ethyl and methyl esters showed a good stability towards oxidation, reaching an equilibrium between scission reactions and macromolecular coupling which permit them to maintain their molecular characteristics during the ageing. ᭧

Research paper thumbnail of Synthesis of Polyacrylonitrile-block-Polystyrene Copolymers by Atom Transfer Radical Polymerization

Macromolecular Chemistry and Physics, 2005

Research paper thumbnail of Drying and oxidative degradation of linseed oil

Polymer Degradation and Stability, 1999

... Ltd. All rights reserved. Permissions & Reprints. Drying and oxidative de... more ... Ltd. All rights reserved. Permissions & Reprints. Drying and oxidative degradation of linseed oil. Massimo Lazzari and Oscar Chiantore Corresponding Author Contact Information , E-mail The Corresponding Author. Department ...

Research paper thumbnail of Photodegradation of acrylic resins used in the conservation of stone

Polymer Degradation and Stability, 1999

The photodegradative behaviour of a series of ®lms of acrylic resins, under controlled conditions... more The photodegradative behaviour of a series of ®lms of acrylic resins, under controlled conditions (RH=50% and T=25 C) has been studied. Films of acrylic resins were applied both on a dolomitic white marble support and on potassium bromide disks. The chemical evolution of the system has been followed by means of FT±IR spectra, HPLC±SEC, colour and water absorption measurements. The main degradation pathway under ultraviolet irradiation is chain scission. The observed rates of photodegradation of the dierent resins may be related to the type of the ester group and to the presence of the a-methyl group in the main chain. # 1999 Elsevier Science Ltd. All rights reserved. 0141-3910/99/$ -see front matter # 1999 Elsevier Science Ltd. All rights reserved. P I I : S 0 1 4 1 -3 9 1 0 ( 9 9 ) 0 0 0 4 8 -8

Research paper thumbnail of Compatibilization effects in the thermal degradation of blends containing SAN and EPDM polymers

Polymer, 1998

ABSTRACT Thermal degradation of blends containing SAN and EPDM was investigated and compared with... more ABSTRACT Thermal degradation of blends containing SAN and EPDM was investigated and compared with that of graft EPDM-g-SAN copolymer molecules. Characterization of decomposition products and of degradation residues was carried out in order to reveal the differences in the degradation processes. With plain mixtures of SAN and EPDM, degradation behaviour is practically additive whereas in the case of EPDM-g-SAN lower volatile products and larger chain scissions are produced. The results can be explained by considering that the degradation process is influenced by the dispersion of the blend components. In phase segregated systems very few interactions take place between the different types of polymers, whereas in the graft copolymer molecular dispersion favours reactive interactions between the structurally different components.