Modellazione molecolare di inibitori organici nel cemento (Molecular modeling of organic inhibitors in concrete)

Corrosion inhibitors are largely used to prevent chloride-induced corrosion in reinforced concrete structures. The interaction mechanisms with the passive film present on steel still requires deeper understanding. In a previous work [1] based on molecular mechanics and molecular dynamics methods [2-5] we considered organic inhibitors adsorbed on γ-FeOOH, comparing theoretical results with experimental data [1]. Here we considered the initial interaction with the inhibitor film and chlorides. In particular, the adsorbed tartrate monolayer show the best behavior thanks to the repulsions by the COO- groups exposed to chlorides, more distant from the γ-FeOOH surface, whereas the dimethylethanolamine film doesn’t have the same repulsion. The molecular simulations are a useful tool to better understand the behaviour of inhibitors in presence of chlorides that can start the corrosio

Heat-Seal Ability and Fold Cracking Resistance of Kaolin-Filled Styrene-Butadiene-Based Aqueous Dispersions for Paper-Based Packaging

Dispersion coatings are offered as alternative solutions to extrusion coating technology for paper-based packaging. In addition to providing barrier properties, waterborne dispersions may implement the processing and converting properties of coated substrates, which are of extreme interest for an effective transfer to the industry. In this work, styrene-butadiene-based aqueous dispersions were formulated considering different amounts of kaolin as pigment. The authors assessed the heat-seal ability, fold cracking resistance, and blocking tendency, comparing the results against commercial dispersion coating grades. Kaolin content dominated the sealing behavior of experimental formulations, changing the minimum heat-seal temperature from 80 °C to >140 °C for 0% and 60% kaolin solid content, respectively. On the contrary, commercial grades were mostly affected by temperature. Additionally, despite the low latex glass temperature (0 °C), experimental formulations generally showed little, if any, blocking. On the downside, increasing kaolin content eases fold cracking, showing a different magnitude according to fold direction and coat orientation yet achieving a higher moisture barrier compared to commercial grades for both folded and unfolded samples

Memristive Anodic Oxides: Production, Properties and Applications in Neuromorphic Computing

Memristive devices generally consist of metal oxide elements with specific structure and chemical composition, which are crucial to obtain the required variability in resistance. This makes the control of oxide properties vital. While CMOS compatible production technologies for metal oxides deposition generally involve physical or chemical deposition pathways, we here describe the possibility of using an electrochemical technique, anodic oxidation, as an alternative route to produce memristive oxides. In fact, anodization allows to form a very large range of oxides on the surface of valve metals, such as titanium, hafnium, niobium and tantalum, whose thickness, structure and functional properties depend on process parameters imposed. These oxides may be of interest to build neural networks based on memristive elements produced by anodic oxidation

Self-cleaning building materials: The multifaceted effects of titanium dioxide

The physical integrity and photocatalytic performance of titanium dioxide (TiO2) deteriorate with aging. Here we propose a pre-treatment with nitric or sulfuric acid of commercial TiO2 nanopowders used in coating, mortars, or paints. The diffuse reflectance is increased between 1500 and 2500 nm by 0.04 and 0.06, respectively, with nitric and sulfuric acid (unaffected by neutralization). Nitric acid causes a decrease in crystallinity and photocatalytic activity, which drops by almost 20%; this drawback is prevented by post-treatment neutralization, which allows to recover initial photocatalytic efficiency and even increase it. Treatment with sulfuric acid shows no significant effect on photoactivity, instead

Improving the optical-radiative properties of TiO2 containing coatings - A side effect of air purification

A manifold positive contribution to climate change mitigation and in the improvement of air quality of built environments can be provided by the use of titanium dioxide (TiO2), also - but not exclusively - as coating for building envelope materials, to spread its beneficial effect on the largest surface area possible. The benefits in applying TiO2 coatings - containing in particular the anatase phase - rely, first of all, on the UV-activated photocatalytic degradation of pollutants mediated by it, which can mitigate pollution arising from industrial sources, heating and transportation. Moreover, changes in wettability upon UV irradiation lead to a superhydrophilic state which, coupled with photocatalysis, results in the so called self-cleaning effect, allowing materials to retain a cleaner and more reflective surface over time. Reducing the impact of aging on the optical-radiative performance of built environment surfaces has a strong influence on the thermal comfort and energy consumption of buildings. Here we present a novel effect observed on long-term durability investigations of commercial siloxane paints containing anatase nanoparticles: an increase in reflectance in the near infrared (NIR) wavelength range upon material aging. This could open the door for HNO3 treatment of TiO2 as a method to boost the self-cleaning efficiency and reflectance of surfaces for building, construction and solar technologies