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An initial assessment of thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry for the identification of oils from dried paint films
No full textConservation 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 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
Contact angle measurements to determine the rate of surface oxidation of artists' alkyd paints during accelerated photo-ageing
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Effect of fluorinated groups on photooxidative stability of polymeric protectives applied on marble
No full textFrom Reactive Latexes to Core-Shell Polymer Nanoparticles for Functional Water-Borne Coatings: Surface Characterization and Stability
No full textPolymeric hybrid materials have recently attracted great interest due to their advantageous
performance relative to the non-hybrid counterparts. Typical hybrid materials contain a compact
inorganic phase bonded (often covalently) with an organic phase, which may be phase-segregated or
dispersed at a molecular level. Recently, hybrids containing polyhedral oligosilsesquioxanes (POSS)
either covalently bonded to or simply dispersed in the polymer matrix have been the subject of
increasing attention. This is due to the potentially interesting properties associated with the unique
structure of the POSS cage, a nanoparticle with silica-like inorganic core (SiO1.5)n (n = 8, 10, 12) and
an outer shell of covalently bonded hydrocarbon or organofunctional groups. These organophilic
POSS derivatives can be incorporated into virtually any polymer and, depending on the specific
polymer-POSS interaction, provide the polymer matrix with enhanced or new application properties.
Copolymerization of monofunctional or multifunctional POSS derivatives is an effective way of
achieving a good dispersion of the POSS moieties, and a wide variety of synthetic routes have been
proposed, mainly based on solution or melt processing. On the other hand, the synthesis of POSScontaining
copolymers by hetherophasic polymerization has received much less attention.
We had previously described the first example of the synthesis of hybrid POSS-acrylic copolymer
latexes by miniemulsion polymerization.1 In the present investigation the thermal, mechanical and
surface properties of the nanocomposite latex films at increasing POSS loadings have been evaluated.
Semi-IPN structures were also produced by photopolymerization of monomer-swollen latex films as a
means to further investigate the microgel structure and mechanical properties of the material
I sistemi informativi per il monitoraggio e la conservazione programmata: alcune applicazioni di una ‘cartella clinica’ per i monumenti
No full textpolymerization of unfluorinated and fluorinated acrylic copolymers for the conservation of stone
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Spectroscopic Characterization Of Ancient Matrices
No full textSince a decade our research group deals with the analysis of ancient cosmetics and drugs, starting from the Roman founds 1-3. Actually, this kind of study involves other research groups supported by a national Fund (PRIN: Colours and ointments in antiquity). Firstly the analysis protocol provides non-destructive analyses and then the more expensive and destructive analyses, such as gas-chromatography-mass spectrometry (GC-MS) methods. The samples analyzed in this study were collected from the Egyptian Museum of Turin, Italy. The discovery of the studied archaeological finds was made by Ernesto Schiaparelli (1906 until 1913) and the archaeological founds were dated from the late III millenium b.C. to early II millenium b.C. The sites of finding were in Assiut (at about 400 Km from Cairo on the bank of the Nile) and Gebelein (south of Assiut), near the southern border with Nubia. In the sarcophagus usually it is possible to find weapons, like bows and arrows, textiles and also ointments. Here the results of the vibrational spectroscopy techniques, such as Raman microscopy (laser 632 nm), FT-Raman spectroscopy (laser 1064 nm) and FT-IR/ATR with a golden gate accessory are reported. These techniques are identified as the most suitable ones for the first approach to ancient samples analysis. Raman microscopy is in fact the most suitable technique in order to identify minor inorganic components and contaminants at the micrometric scale inside these complex matrices4. This technique can easily identify compounds like lead oxide, vermillion, rare minerals, (etc.) that could give interesting informations about the provenance of the raw materials and the original composition of the formulate. In the present study some data are reported concerning the composition of five ancient Egyptian samples. It can be observed that Titanite is present, a mineral possibly coming from mines in Southern Egypt5.Concerning to organic materials, their possibility of identification, is very different from that of inorganic ones. Some compounds were rapidly degraded, some others persisted till to present day, often unchanged (e.g. wax). Historical samples give a chemical variability due to the natural products, in addiction, ageing and degradation processes make very difficult to recognize raw materials originally present. For understanding the possible changes undergone by materials in ageing, a specific database of spectra must be available. Some thirty raw materials were chosen among oils, gums, animal fats and waxes commonly employed in the ancient preparations. The reference materials were in laboratory artificially aged by heating, photo-oxidation and enzymatic degradation. Some artificial materials aged produced different alterations according to the type of ageing. The comparison to one remain sample and our database spectrum showed a correspondence with the enzymatically degraded palm oil spectrum. This indicates the importance of this database in recognising the organic materials into archaeological holders
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