1,720,979 research outputs found
Impiego di argille anioniche lipofilizzate come gelificanti per oli vegetali
No full textSono stati recentemente sviluppati nuovi prodotti nanostrutturati per la gelificazione di oli vegetali, da impiegare in formulazioni topiche a uso cosmetico e farmaceutico, che derivano dalla funzionalizzazione di argille anioniche note anche come di idrotalciti (HTlc), solidi inorganici lamellari a base di idrossidi doppi di metalli bivalenti e trivalenti largamente impiegati in campo farmaceutico e cosmetico [1, 2]. Raramente presenti in natura, queste argille sono facilmente sintetizzate in laboratorio con metodi green che prevedono l’uso di materie prime semplici e poco costose e di sola acqua come solvente. Le HTlc presentano dei vantaggi rispetto alle argille naturali in quanto durante la preparazione è possibile controllare il grado di cristallinità e ottenere un prodotto finale puro sia dal punto di vista chimico che microbiologico.
HTlc a base di magnesio-alluminio (MgAl-HTlc) e zinco alluminio (ZnAl-HTlc) sono state lipofilizzate, quindi rese affini a un ambiente oleoso, grazie all'inserimento nella regione interstrato di catene alchiliche lineari C18 (oleato, stearato) o C12 (dodecilsolfato). Questa frazione organica si va ad intercalare in modo altamente ordinato nello spazio intra-lamellare dando origine a composti nanostrutturati costituiti da un host inorganico e un guest organico.
I nuovi gelificanti sono stati caratterizzati con spettroscopia di diffrazione di raggi X, analisi termica TGA, analisi granulometrica e microscopia SEM.
Sono polveri microfini, impercettibili una volta miscelate con l'olio; non producono un effetto abrasivo per uso topico e la loro natura fisica permette un'agevole e omogenea dispersione consentendo di realizzare facilmente degli oleogeli (lipogeli).
Le argille lipofilizzate sono state impiegate per gelificare vari oli vegetali, destinati a formulazioni topiche sia farmaceutiche che cosmetiche (oliva, mandorle, jojoba, argan, cocco, calendula, ricino, ecc.), con vari rapporti olio-gelificante. In tutti i casi si ottengono dei lipogeli molto gradevoli, abbastanza consistenti e facilmente spalmabili.
E’ stata inoltre studiata la microstruttura, responsabile della gelificazione, che si viene a creare dopo il contatto olio-gelificante. Infine, i lipogeli sono stati sottoposti a studi reologici che forniscono dati importanti relativi alle caratteristiche di spalmabilità, spandibiltà, estrudibilità della formulazione
Materiali innovativi, semplici, economici, atossici ed ecofriend per aumentare la sicurezza e l'efficacia di prodotti per la salute.
No full textElongational flow‐induced microstructure evolutions in polypropylene/layered double hydroxides nanocomposites
Full text linkIn this work, the effect of the non-isothermal elongational flow on the morphology and mechanical properties of polypropylene (PP)-based nanocomposites containing Mg-Al layered double hydroxides (LDHs) modified with stearate or oleate functional groups has been investigated. In particular, nanocomposites containing 5 and 10 wt% of LDHs prepared through melt compounding were subjected to uniaxial elongational flow at the exit of the extruder, leading to the formation of fibers characterized by different draw ratios (DRs). The mechanical characterization of the fibers demonstrated a progressive enhancement of the tensile strength as a function of the DR with increasing the content of nanofillers. Notably, for the fibers stretched at a DR of 200 and containing 10 wt% of LDHs modified with oleate groups, the tensile strength increased fourfold as compared to that of the unfilled matrix. These results have been attributed to a progressive enhancement of the extent of the dispersions of the embedded LDHs induced by the application of the elongational flow, as also confirmed by morphological analyses. In all, the obtained results demonstrated the beneficial effect of the elongational flow in promoting the achievement of superior mechanical properties in LDHs-containing nanocomposites, hence widening the application field of these nanostructured materials.Highlights PP/organomodified LDH nanocomposites were obtained through melt compounding. Nonisothermal elongational flow was applied to the extrudates at the die exit. Anisotropic fibers showed progressively enhanced tensile strength values. Elongational flow promoted a gradual evolution of the material microstructure. A gradual improvement of the nanofiller dispersion was observed upon elongation.Non-isothermal elongational flow promotes the achievement of enhanced nanofiller dispersion and improved tensile properties in LDHs-containing nanocomposites. imag
Layered Double Hydroxide Nanocomposite Coatings for Improved Flame Retardancy of Polyethylene-Based Copolymers
Full text linkThis work proposes a coating approach for obtaining flame-retardant ethylene–vinyl acetate (EVA) and ethylene–butyl acrylate (EBA) copolymer-based materials. Nanocomposite films of EVA and EBA were first produced by cast extrusion, with two types of layered double hydroxides (LDHs) differing in the aspect ratio used as nanofillers. Subsequently, the films were applied as a coating to the corresponding neat copolymer substrate, and the combustion behavior of the so-obtained samples was evaluated through cone calorimeter tests. Despite the small amount of nanofillers (0.5 wt.% considering the whole specimen), the application of the coatings significantly improved the time to ignition compared to the pristine copolymers, while the shape of the heat release rate curves and the relative peak values remained relatively unchanged. The effect of the embedded nanofillers in delaying the ignition was more effective for the EVA-based systems than for the EBA ones (showing an increment of 30% and 12%, respectively, compared to the uncoated samples), likely due to the more homogeneous dispersion of the LDHs obtained in the first case. The obtained results demonstrate the effectiveness of the coating approach, since it allows the flame retardant
action to be concentrated on the surface of a polymer system, where combustion specifically takes place, while minimizing the required amount of flame retardant
Co-precipitate of one or more stilbene polyphenols and their derivatives in lamellar anionic solids, its applications and related preparation method.
No full textMateriali inorganici per il miglioramento delle proprietà biofarmaceutiche di ingredienti attivi.
No full textNanostructured Cu/ZnO/Al2O3 catalysts of OSRM process based on hydrotalcites prepared with different syntetic routes
No full textA simple and effective method to form metallic nanoparticles onto composites made up of organic polymers and layered inorganic ion exchangers as fillers
No full textIntegrated XRPD-MD Study of Thermal effects on mixed metal (Cu/Zn/Al) layered double hydroxides (LDHs), precursors for the OSRM reaction catalysts XXXV Congresso Nazionale della Divisione di Chimica Inorganica della Società Chimica Italiana.
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