Elisa Cappelletto

Hydrophobic siloxane paper coatings: the effect of increasing methyl substitution

Paper is an organic material widely used in cultural heritage and mainly composed of cellulose mixed with lignin, hemicellulose and small amounts of additives. This paper deals with siloxane coatings on pure cellulose paper, applied by sol–gel dipping in sols prepared with different siloxane precursors (tetraethoxysilane, methyl triethoxysilane, dimethyl diethoxysilane, trimethyl monoethoxysilane). The coated samples were characterized using various techniques (Fourier Transform Infrared Spectroscopy FT-IR, Nuclear Magnetic Resonance NMR and Scanning Electron Microscopy and Energy Dispersive Spectroscopy SEM–EDS), measuring their mechanical properties, flame resistance and contact angles, and a colorimetric test. The coated samples’ behavior was more hydrophobic the higher the methyl number of siloxane precursor, regardless of the coating’s thickness. Increasing the thickness improved the mechanical and thermal properties. The thickest coatings were obtained using a double coating process and a basic catalyst for the hydrolysis step, but this latter condition facilitated the formation of surface agglomerates, which make the paper too stiff and yellow.

Wood surface protection with different alkoxysilanes: a hydrophobic barrier

Abstract This paper describes coatings on wood surfaces made by dipping the wood into solutions of different alkoxysilanes. The silanes used as precursors contain different organic groups [R’Si(OR’’)]. These materials tend to deposit as inorganic–organic polymeric films, where the organic groups (aliphatic hydrocarbons, fluorinated hydrocarbons or aromatic substituents) show hydrophobic properties, which reduce the wettability of the surface. The effects of these treatments on the wood surface were extensively studied using various analytical techniques: scanning electron microscopy with energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, water contact angle measurements, and flame resistance tests. The resulting data show that the chemical treatment changes the wood’s surface energy, reducing its wettability and reaction to fire. The main innovative finding of this research is that the coatings obtained from a cheaper precursor have a similar performance to that of the more expensive precursors normally used.

Properties of Rapeseed (Brassica napus) Stalks Fibers

For any type of pulping process, the chemical composition of raw materials is the determining factor of pulping yield, while fiber dimensions establish the pulp strength and dictate its final use. In this study, an attempt was made to present the chemical and morphological characteristics of Brassica napus stalk fibers. The chemical compositions of raw material and Kraft-delignified fibers were analyzed for the macromolecular substances content (cellulose, hemicelluloses, pentosans, and lignin) and low- molecular-weight components (extractives, soluble, inorganic). With regard to morphology features, such as fiber length, width, and wall thickness of pulp, samples were measured using digital microscope system and scanning electron microscope. It is concluded that the properties of rapeseed stalk fibers, which are commonly encountered in other nonwood and hardwood papermaking fibers, have the potential for being used for manufacturing different paper products.

Chloride-based route for monodisperse Cu2ZnSnS4 nanoparticles preparation

A new approach based on hot injection method is proposed to gram-scale Cu2ZnSnS4 nanoparticles production minimizing the use of organic solvents. Nanocrystal synthesis was performed starting from metal chlorides and pure sulphur powder and using Oleylamine as capping agent. As a result, core-shell nanoparticles with a narrow size distribution were obtained.

Mechanical activation of Efavirenz: the effects on the dissolution and inhibitory behavior

Abstract A poorly water-soluble drug (Efavirenz) was mechanically activated by ball-milling. The effect of the mechanical activation on the dissolution behavior and bioavailability was investigated revealing possible correlations with the grinding action, in terms of crystallinity, particle size and morphology.With proper selection of the grinding parameters the dissolution kinetics can be controlled, both in terms of dissolution velocity and as amount of dissolved drug. In vitro biological tests show that milling does not impair the ability of Efavirenz to inhibit HIV-1 infection (p value >0.05); the IC50 values of ground Efavirenz is indeed lower than values for the pristine micronized powder.