Aquazol as a binder for retouching paints. An evaluation through analytical pyrolysis and thermal analysis

Aquazol poly (2-ethyl-oxazoline) is a tertiary aliphatic amide, with physical and chemical properties that are exploited in a variety of ways, from pharmaceutical applications to the conservation of cultural heritage. In this study, we evaluated the use of Aquazol as a new binder for retouching paint in the restoration of artworks. Aquazol 500 admixed with various formulations of organic red pigments was used to prepare paint replicas which were artificially aged and investigated by a multi-analytical approach based on analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), and thermogravimetry (TG), complemented by FTIR and LIBS spectroscopy. This is the first study on the ageing phenomena of Aquazol 500 using analytical pyrolysis and thermogravimetric analysis. The influence of the pigments' components on the pyrolysis behavior of Aquazol was also investigated. The paint replicas did not show significant modifications during artificial ageing. This thus highlights the optimal properties of Aquazol 500 as a binder for retouching, in addition to its already established suitability as a filler or consolidant in the restoration of artifacts. Interestingly, when Aquazol 500 is used in formulations containing organic pigments, Aquazol-pigment interactions are observed, strongly depending on the pigment used

Chemico-physical characterization and evaluation of coating properties of two commercial organosilicons: Hydrophase® and Disboxan 450®

Two commercial organosilicons, Hydrophase®, a monomeric dispersion, and Disboxan 450®, an oligomeric dispersion, were studied in pure form and applied on acrylic paint replicas. Their physico-chemical characteristics, coating properties, and interaction with acrylic paint replicas were evaluated by TG, DSC, FTIR, and contact angle measurements. Hydrophase® showed a higher interaction when used on the top of acrylic paint replicas than Disboxan 450®. No appreciable modification was detected after two years of natural ageing

Kinetics of release and antibacterial activity of salicylic acid loaded into halloysite nanotubes

In this work halloysite (Hal) nanotubes were used as nanocontainers for salycilic acid (SA) in a perspective of its use in active packaging for food industry. The system Hal/SA was investigated for its ability to stabilize Hal suspensions by turbidimetry, its release kinetics in water by UV spectroscopy and its antibacterial activity against Pseudomonas fluorescens IMA 19/5 by Isothermal Micro Calorimetry (IMC). IMC is a sensitive and nondestructive technique and allows the study of a wide range of relatively slow processes (hours and days) in solutions. The system Hal/SA resulted to stabilize Hal suspension in water and to release SA in a controlled way over 50 h. Moreover the SA released by Hal/SA showed an antibacterial activity at lower concentrations than free SA, likely due to the close contact of bacteria and Hal in the reaction vessel

Novel configurations for a citrus waste based biorefinery: From solventless to simultaneous ultrasound and microwave assisted extraction

Innovative extraction configurations for the biorefining of a biomass waste (citrus peel) were developed in this work. Non-conventional energies, such as microwaves (MW) and ultrasounds (US), were directly irradiated to the fresh orange peel using a versatile MW coaxial dipole antenna. This particular MW configuration enabled us to build two new extraction systems: (1) a coaxial solventless MW-assisted extraction (SMWAE) approach and, (2) a simultaneous ultrasound coaxial MW-assisted hydrodistillation (US-MWHD) method. The yield and chemical composition of the essential oils (EOs) of the orange peel obtained by the two innovative approaches were analyzed as a function of the extraction time and compared with those from coaxial microwave hydrodistillation (MWHD) and conventional hydrodistillation (CH). The EOs were chemically characterized by GC and GC-MS analysis. The residue mash was then used to extract pectin by a MW-assisted procedure. The structure and thermal stability of the pectin were investigated by FTIR and TG. The biorefining of EOs and pectin from a citrus waste maximises the benefits of our proposed green methodologies, which involve safe operability, faster processing and easy scalability. Furthermore, the energy consumed per unit mass of products in each step of the orange peel biorefining clearly showed that the most promising approach is SMWAE (since it is around 27 times lower than the CH approach). MWHD and US-MWHD also showed more than 60% energy savings compared to CH