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The great efforts to reduce the environmental impact of composite materials by replacing synthetic components with bio-based ones are involving also sandwich structures. Agglomerated cork proved to be a feasible alternative to traditional polymeric foam as core material. Sandwich structures are extremely prone to impact events which can cause the direct exposure of the core material to the external environment making fundamental to know how its out-of-plane properties can be influenced by external factors such as sunlight and rain. The present work assessed the effects of UV accelerated aging and freeze–thaw (FT) cycles on the compressive behavior of two agglomerated corks with different densities providing also a direct comparison with a traditional PVC foam. Agglomerated cork compressive properties increase when exposed to UV accelerated aging up to 600 h, determining an increase of 31 % and 9 % in the compressive modulus for the less dense and denser cork, respectively. No significant changes were observed for the synthetic foam. FT cycles on as-received specimens induce a decrease in cores compressive properties after 30-day cycling, with a reduction in compressive modulus of approximately 11 % for PVC foam and of 12 % and 11 % for the less dense and denser cork, respectively. [ABSTRACT FROM AUTHOR]

Cultural heritage stone materials frequently experience significant discoloration induced by copper corrosion products, especially calcareous stones associated with bronze or copper statues and architectural elements. This alteration originates from the corrosion of unprotected copper, resulting in the formation of various Cu minerals and the migration of soluble ions to adjacent stone materials. Traditional cleaning methods involve mechanical, chemical, and laser techniques, which are generally time-consuming, costly, not ecological, or can possibly damage original materials. The loading of highly effective chelating agents, such as ethylenediaminetetraacetic acid (EDTA), into hydrogels has recently been exploited. However, the preference for synthetic hydrogels has been prominent until now, although they lack renewability and biodegradability and require high costs. This study explores for the first time the potential to clean copper corrosion with bacterial nanocellulose (BC) loaded with EDTA as a biologically based, sustainable, and biodegradable hydrogel. The BC hydrogel was characterised by field emission–scanning electron microscopy (FE–SEM), X-ray diffraction analysis (XRD), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR), simultaneous thermal analysis (TG-DSC), and tensile testing. It revealed a nano-fibrous structure with high crystallinity and purity and mechanical properties suitable for cultural heritage applications. The EDTA-loaded hydrogel effectively removed copper stains from marble after 120 min of application. Micro-Raman and colorimetric analyses assessed the cleaning efficacy. The study introduces bacterial nanocellulose as a green and effective alternative for heritage conservation, aligning with sustainable methodologies in stone conservation. [ABSTRACT FROM AUTHOR]

Lidars have many applications in different fields, including the field of Cultural Heritage. The purpose of this study is to evaluate a scanning hyperspectral lidar prototype developed at ENEA Center of Frascati as a useful tool for colorimetric analysis when samples cannot be studied with standard contact instruments. A certified X‐Rite Color‐checker sample, consisting of 24 colored blocks with a coordinated colorimetric certificate, was analyzed. In order to obtain colorimetric data from the reflectance spectra, the precepts of the Commission de l'Éclairage were followed and an algorithm was developed to calculate the color difference between the certified values of the Color‐checker and commercial and non‐commercial spectrophotometers and those obtained by the lidar, confirming this latter as a useful tool for remote colorimetry. [ABSTRACT FROM AUTHOR]