Papers by Bertrand Lavedrine
Heritage
Chromogenic reversal films (or color slides) are first-generation positive transparencies. These ... more Chromogenic reversal films (or color slides) are first-generation positive transparencies. These were used for various purposes, namely as an artistic medium, especially from the 1960s onwards. However, these materials are intrinsically vulnerable to chemical degradation and have poor long-term stability. Although over time significant improvements have been achieved in the stability of chromogenic products, chromogenic dyes are highly susceptible to oxidation and hydrolysis, both induced by light and/or relative humidity and temperature, leading to the fading and shift in the original color balance of the images. During the present investigation, a gap of knowledge regarding chromogenic materials in general, and chromogenic reversal films specifically, was detected. Today, there is still no methodology to identify the dyes present in a specific work and, therefore, to study their chemical mechanism of degradation. From this premise and focused on case studies from the Portuguese ar...
HAL (Le Centre pour la Communication Scientifique Directe), Sep 14, 2022
Journée doctorale, Feb 1, 2015
Metal-Organic Frameworks (MOFs) for Environmental Applications, 2019
Abstract Air quality is a major worldwide concern because of its impact on human health and the e... more Abstract Air quality is a major worldwide concern because of its impact on human health and the environment. Volatile organic compounds (VOC) and toxic chemicals emissions contribute strongly to the air pollution. This chapter summarizes recent progresses dealing with metal-organic frameworks (MOFs) and the capture of VOCs or toxic gases in a review of environmental applications. We mainly analyze the influence of MOFs physicochemical parameters over the efficiency and selectivity of the adsorption. This chapter is divided into two parts: capture of VOCs (hydrocarbons, alcohols, aldehydes, ketones, and carboxylic acids) and capture of toxic chemicals (SO 2 , H 2 S, CO, and NO).
Le polychlorure de vinyle (PVC) plastifie est un plastique tres present dans les collections patr... more Le polychlorure de vinyle (PVC) plastifie est un plastique tres present dans les collections patrimoniales et dans un etat de conservation juge souvent mediocre. Les degradations les plus frequentes sont l’exsudation et la perte de souplesse des objets qui sont liees a la migration progressive du plastifiant vers la surface du materiau. Le projet vise a mieux comprendre les processus d’alteration des objets en PVC plastifies et a preconiser des conditions de conservation et des traitements de restauration. Cette etude sera realisee en parallele sur des PVC de formulation simplifiee et sur des PVC vieillis naturellement en musee. La cinetique de migration du plastifiant et les modifications structurales des chaines PVC seront caracterisees au cours d’un vieillissement artificiel des objets realise dans les conditions les plus representatives d’un environnement museal d’exposition ou de conservation. L’impact du nettoyage des surfaces sera etudie en terme d’efficacite mais surtout de ...
Journal of Cultural Heritage, 2020
To prevent serious maritime accident and eliminate the cause of the potential maritime accidents,... more To prevent serious maritime accident and eliminate the cause of the potential maritime accidents, Maritime Safety Audit Scheme was formally institutionalized through amendment of Maritime Traffic Safety Act(May 27, '09). At the initial step of the enforcement of the law, it has risen the necessity of amending the present institution concerning with the range of applicable business, method of practice, detailed technical standards in the assessment articles, etc. Among them, the assessment of marine traffic congestion has been practiced as a mandatory assessment article, but it is analyzed that the assessment doesn't reflect current variation of ships' size and its speed. By analyzing the status of assessments on marine traffic congestion so far and collecting experts' opinion, this paper suggests draft amendments to improve technical standards on the assessment of marine traffic congestion.
Studies in Conservation, 2019
Aiming at contributing for the preservation of black and white (b/w) film-based negatives held by... more Aiming at contributing for the preservation of black and white (b/w) film-based negatives held by Portuguese archives, four photographic collections from the first half of the 20 th century were selected to study. During the macro assessment of the collections the preservation condition and hues found on the photographic negatives of the Elmano Cunha e Costa (ECC) were noticed, distinguishing this the image layer was analysed by µ-Energy Dispersive X-ray Fluorescence (µ-EDXRF) and Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS). Additionally, to assess the base decay and its effect on the formation of hues, the plastic supports were characterized by µ-Fourier Transform Infrared Spectroscopy (µ-FTIR). To complement the assessment of the film-base decay, pH was measured by using combined micro-electrodes. The identification of mercury, iodine, chromium and iron by µ-EDXRF allowed to correlate the hues found in the negatives with chemical corrective treatments performed to improve the image quality. SEM-EDS confirmed those results and proved that the elements found were in the photographic emulsion layer.
Cellulose, 2017
The aim of the research was to evaluate the influence of certain components of paper such as lign... more The aim of the research was to evaluate the influence of certain components of paper such as lignin and papermaking additives (fillers and sizing) on the efficiency of a recently proposed treatment for simultaneous deacidification and mechanical strengthening with polyaminosiloxane copolymer networks. Mixed mechanical and chemical pulp papers containing various additives were treated with aminoalkylalkoxysilanes (AAAS) by immersion or by spray. Upon treatment, the deposited alkaline reserve varied from 0.34 to 1.14 mol kg-1. For all the papers, copolymers formed from binary mixtures of a diand a tri-functional AAAS provided the best improvement in the mechanical properties, i.e. in the tensile strength and the folding endurance, indicating an increase in the interfiber bonding energy and in the paper flexibility and plasticity, respectively. It was found that fillers had no influence while sizing hampered the efficiency of the treatment. The presence of mechanical pulp was shown to have a significant impact on the effect of the treatments as well by increasing the tensile resistance more than the folding endurance, indicating an increase in the paper rigidity. This observation was attributed to the response of lignin to the treatment.
Heritage Science
Korean hand papermaking is a renowned cultural tradition in the Korean peninsula. It is still pra... more Korean hand papermaking is a renowned cultural tradition in the Korean peninsula. It is still practiced while scientific analysis of paper itself from a large data set is rare. In this study, a set of more than three hundred Korean handmade papers, collected in a reference collection book Hanji: Korean handmade paper, were chemically investigated, and their property data such as colour, pH, grammage, thickness, tensile strength, folding endurance were statistically analysed in order to determine general features for Korean papers. The influence of different paper sheet formation methods (Heullimtteugi vs Gadumtteugi) were revealed by multivariate data analysis and the chemical profiles of raw materials were studied by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The Korean handmade paper samples display colour gamut in the colour space L* (69.9–95.9), a* [(−3)-3], b* (0–20), most have neutral/alkaline pH values. Paper density, fiber orientation and physical properties ...
Polymer Degradation and Stability, 2016
Museum artifacts made of polyurethane ester foam are frequently affected by conservation issues m... more Museum artifacts made of polyurethane ester foam are frequently affected by conservation issues mainly related to the loss of their mechanical properties. Modification of mechanical properties often leads to structure crumbling and in some cases to the loss of the entire artifact. A previous study evaluated the possibility to reinforce new flexible industrial polyurethane ester foam with aminoalkylalkoxysilane (AAAS) based treatments. In this paper AAAS are applied on artificially degraded polyurethane ester foam to investigate the possibility to reinforce already degraded objects. Two AAAS, the 3-Aminopropylmethyldiethoxysilane and the N-(2-Aminoethyl)-3-aminopropylmethyldimethoxysilane have been tested. AAAS solutions at different concentrations have been used to apply the monomers on the foam samples by
Owing to their high porosity and tunability, porous solids such as Metal-Organic Frameworks (MOFs... more Owing to their high porosity and tunability, porous solids such as Metal-Organic Frameworks (MOFs), Zeolites and Activated Carbons (ACs) are of great interest in various fields for instance gas separation, catalysis, water and air purification, among others. These materials are usually in powder form and need to be shaped in some practical way that does not modify their intrinsic property (i.e. porosity). Making porous, freestanding and flexible sheets is a relevant shaping strategy. However, achieving high loadings (> 70 wt %) can challenge mechanical properties. We have developed a new green and simple method that combines two cellulosic fibrous structures of different size, i.e. softwood bleached kraft fibres (S) and nano-fibrillated cellulose (NFC), to form a high porous solids loading (>70 wt %) paper sheet. This dual fiber system produces a synergistic effect, where S provides flexibility while NFC acts as a nanostructuring and mechanical strengthening agent with an opti...
Owing to their high porosity and tunability, porous solids such as Metal-Organic Frameworks (MOFs... more Owing to their high porosity and tunability, porous solids such as Metal-Organic Frameworks (MOFs), Zeolites and Activated Carbons (ACs) are of great interest in various fields for instance gas separation, catalysis, water and air purification, among others. These materials are usually in powder form and need to be shaped in some practical way that does not modify their intrinsic property (i.e. porosity). Making porous, freestanding and flexible membranes is a shaping strategy. However, high loadings (> 70 wt %) can challenge mechanical properties. We have developed a new sustainable and simple method that combines two cellulosic fibrous structures of different size to form a high porous solids loading (>70 wt %) paper membrane: softwood bleached kraft fibres (S) and nano-fibrillated cellulose (NFC). This dual fiber system produces a synergistic effect, where S provides flexibility while NFC acts as a nanostructuring and mechanical strengthening agent with an optimal S:NFC=1:2...
Actualité de la …, 2012
La désacidification de masse » Journée d'étude, mardi 29 mars 2011 Désacidification et renforceme... more La désacidification de masse » Journée d'étude, mardi 29 mars 2011 Désacidification et renforcement des papiers très dégradés par les aminosilanes L'exemple de l'AMDES
Journal of Cultural Heritage, 2020
The effects of LDPE and PET in contact with heritage object made in PVC were studied and compared... more The effects of LDPE and PET in contact with heritage object made in PVC were studied and compared with silk paper during an artificial aging consisting in a temperature cycle and under controlled relative humidity. Color changes, morphological changes of the surface, plasticizers loss and surfaces properties were assessed over aging time. More pronounced color changes than for the references (without contact material and with silk paper) are observed for both contact materials but are more significant for PET whose surface has brown spots from three months of aging. The plasticizers cross LDPE from the outset of the aging but zein (protein additive) is evidenced only on the side in contact with the PVC. The PVC sample in contact with PET shows phtalic acid from DOP degradation but it remains on the PVC surface.
Museum artifacts made of polyurethane foam are affected when the foam loses its mechanical proper... more Museum artifacts made of polyurethane foam are affected when the foam loses its mechanical properties. While effective treatments are available for polyurethane ether foams, no convenient consolidation treatments exist for polyurethane ester foams. One possible solution is aminopro-pylmethyldiethoxysilane (AMDES), which has already been used successfully for deacidification and consolidation of paper. To explore this possibility, we tested AMDES on industrial flexible polyurethane ester foam samples. Various concentrations of AMDES solutions were applied to unaged samples and to samples that had been artificially aged hydrothermally. Mechanical properties were studied using a compression force deflection test, and the results showed that AMDES treatment improved the resistance to compression of both aged and unaged foams. To investigate the AMDES distribution in the thickness of the samples, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were u...
Polymer Degradation and Stability, 2012
Restaurator, 2003
Five different qualities of paper were selected in order to have samples which were neutral, acid... more Five different qualities of paper were selected in order to have samples which were neutral, acidic and alkaline (Table 1). Some of them were immersed in aqueous solutions or exposed to an acidic environment in order to modify the pH value and to make the paper acidic or alkaline (Table 2). Another batch was deacidified using CSC Book Saver Spray 12. The samples were sprayed on one side and then air dried.
Restaurator, 2002
Washing acidic paper documents in aqueous baths in order to rid them of soluble acids is a common... more Washing acidic paper documents in aqueous baths in order to rid them of soluble acids is a common conservation treatment. Often, alkaline salts are added to the wash water to neutralize all the acids and leave an alkaline reserve in the paper. Depending on the sensitivity of the writing or drawing medium to water, alkaline salts can alternatively be dissolved in alcohol or in a mix of alcohol and water. However, in a museum or a library/archive context such procedures are not always possible because they are time consuming. When working in terms of collection priorities preventive conservation measures must prevail over lengthy treatments. In some cases, when treatment is necessary, but time is limited, the use of a deacidification spray is appealing, since it is fast and does not require unbinding. It seemed interesting to test the efficiency of the deacidification spray CSC Book Saver ® as a new deacidification alternative recently introduced on the European market. This study is not intended as a thorough product review but rather as a technical note to help paper conservators and, more generally, library and archives collection keepers form their own opinion. Cold extract pH 1 and alkaline reserve 2 were measured on deacidified papers. The paper surface was analysed by scanning electron microscopy and energy dispersive X-ray (SEM/EDX) to evaluate the homogeneity of the alkaline deposit. The consumption of the buffer reserve over time was simulated by exposing the papers to nitrogen dioxide 3 in a pollution chamber 4. Changes in pH and colour were monitored and the protective effect of the neutralizing agent on the cellulose was analysed by size exclusion chromatography. PAPERS TESTED We tested a mechanical pulp paper, sized with alum and rosin, taken from a book edited in 1931, which was very acidic and yellow. Such paper would be a typical
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Papers by Bertrand Lavedrine