1. Functional coatings with ethyl cellulose-calcium carbonate alkaline nanoparticles for deacidification and mechanical reinforcement of paper artifactsMatej Bračič, Jasna Malešič, Mihael Brunčko, Doris Bračič, Alenka Ojstršek, Tea Kapun, Sašo Gyergyek, Karin Stana-Kleinschek, Tamilselvan Mohan, 2025, izvirni znanstveni članek Opis: Paper artifacts susceptible to acid hydrolysis and mechanical stress require effective conservation methods to ensure their longevity. In this study, a novel approach for the deacidification of acidic paper using calcium carbonate (CaCO3) [1,2]-ethylcellulose nanoparticles (CaCO3-EC NPs) dispersed in a non-aqueous ethyl acetate solution is presented. The dispersions were carefully prepared and applied to model acidic paper samples using a dipcoating method and then analyzed for their effectiveness. Transmission electron microscopy showed the formation of agglomerates containing quadrangular alkaline nanoparticles with diameters of 40 to 100 nm and a total agglomerate size of 250 nm. Hydrodynamic analyzes indicate the presence of a swollen ethyl cellulose coating on these agglomerates, which facilitates their dispersion. The results show the effectiveness of the CaCO3-EC NPs system in neutralizing acidic components (change of paper pH from 4.3 to 7) due to the homogeneous distribution within the paper substrates, effectively arresting the degradation processes. Acid-base titration showed a linear correlation between the concentration of alkaline nanoparticles and the alkaline reserve, emphasizing the role of ethylcellulose in facilitating particle transport within the paper matrix. In addition, ethylcellulose was found to improve the mechanical properties of the treated paper, as demonstrated by the standard mechanical tests. Importantly, the optical properties remained unchanged after treatment, as no adverse changes in color were observed. These results underline the effectiveness of the developed deacidification dispersions for the treatment of acidic paper and potentially other cellulose-based cultural heritage documents prone to acidic degradation. This approach offers promising implications for preserving and restoring valuable historical materials.
Ključne besede: ethylcellulose, calcium carbonate, functional coating, deacidification, strengthening, cultural heritage
Objavljeno v DKUM: 20.03.2025; Ogledov: 0; Prenosov: 1
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2. Pressing of partially oxide-dispersion-strengthened Copper using the ECAP processMatija Kos, Janko Ferčec, Mihael Brunčko, Rebeka Rudolf, Ivan Anžel, 2014, izvirni znanstveni članek Opis: A combination of internal oxidation (IO) and equal channel angular pressing (ECAP) was used to explore the possibility of uniting the mechanisms of dispersion and deformation strengthening to improve the properties of a Cu-Al alloy with 0.4 % Al. The IO of Cu-Al billets served in the first step of the experiment as a means for dispersion, strengthening the mantle of the billets with a fine dispersion of nanosized oxide particles. The experimental procedure continued with deformation strengthening performed by ECAP, which allowed an intense plastic strain through simple shear. Material flow in a partly internally oxidized Cu-0.4 % Al billet and in a homogenous reference sample made of modelling mass was also studied to analyse, on the macroscale, the influence of the internal oxidation zone (IOZ) on the material flow behaviour during the ECAP process. The analysis was performed with the aim of revealing the uniformity of the strain distribution and to obtain information about the deformation strengthening across the volume of the billet. We found that the oxide particles have a minor influence on the material flow on the macroscopic scale during the ECAP process. However, the degree of deformation strengthening in the IOZ was much lower than in the unoxidized core region. The combination of IO and ECAP allows us to produce a Cu composite composed of a hardened oxidized mantle region with good electrical and thermal conductivity and a high- hardened core region. This combination represents a new technological route for the production of high-hardness Cu composites, which could also be used at higher temperatures.
Ključne besede: ECAP, Cu-Al alloys, strengthening mechanisms, internal oxidation
Objavljeno v DKUM: 17.03.2017; Ogledov: 1469; Prenosov: 98
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