Search results for "Materiali"
showing 10 items of 876 documents
Ageing of isotactic polypropylene due to morphology evolution, experimental limitations of realtime density measurements with a gradient column
2006
Abstract Ageing in crystalline polymers is responsible for the deterioration of physical properties leading, for example, to a decrease in toughness and to dimensional changes that are to some extent responsible for warpage and scrap production in injection molding. Since, it depends on the mutual transformation of stable and metastable phases, being always related to changes in morphological organization, it is here preferred to call it ‘Morphological ageing’. Although, one would expect the ageing regime to be determined by the complex morphology with amorphous phases of different mobility and eventually multiple crystalline phases, transformed into each other at an associated transition, …
Analisi integrata tramite XRF e LIBS per lo studio dei materiali pittorici
2011
Lo studio dei materiali pittorici è uno degli obiettivi primari per la caratterizzazione storico- artistica delle opere d’arte poiché fornisce informazioni utili circa i materiali originali e di degrado, la tecnica di esecuzione ed eventuali interventi di restauro pregressi. Tuttavia, la complessità delle indagini archeometriche è legata alla necessità di garantire la salvaguardia del bene culturale che rende essenziale l’uso di tecniche di indagini non o micro invasive. Tra le metodologie d’indagine integrata, l’uso della fluorescenza a raggi X (XRF) e della spettroscopia mediante ablazione laser (LIBS) risponde a tale esigenza e risulta particolarmente utile per la complementarietà delle …
Pull-off adhesion of hybrid glass-steel adhesive joints in salt fog environment
2016
The aim of this paper was to evaluate the durability behaviour of glass/steel adhesive joints exposed to salt fog environmental conditions for ten weeks, according to ASTM B117 standard. To this scope, pull-off mechanical tests were carried out in order to evaluate the performances evolution and damage phenomena of the adhesive joints during the ageing exposition. Two different types of adhesives were compared (i.e. epoxy and polyurethane ones). Moreover, the effects of the glass surface condition and the presence of a basalt mat layer within the adhesive thickness were evaluated. The mechanical performances were related with the occurred failure mechanisms. Epoxy-based joints showed higher…
ANALISI STRUTTURALE DI UN TIMONE PER ALISCAFI
2012
Attualmente i sistemi di controllo direzionale (timone) e di stabilità (flap) dei battelli veloci per il trasporto passeggeri (HSC) sono realizzati con elementi scatolari in acciaio. Ciò è essenzialmente dovuto alle notevoli sollecitazioni idrodinamiche che tali elementi sopportano a causa dell’elevata velocità di crociera. L’esigenza di ridurre il peso di tali elementi e di aumentarne la resistenza alle azioni corrosive esterne spinge ad una ricerca su materiali e tecnologie di fabbricazioni innovative. In questo studio è presentato il progetto di un timone, realizzato in materiale ibrido composito e acciaio, da impiegare su un battello per trasporto veloce passeggeri.
Anállisis de los factores e internos a las organizaciones que explican la materialidad de la información no financiera. La situación de las empresas …
2022
El deterioro ambiental relacionado con la crisis climática, la pérdida de ecosistemas y biodiversidad global, junto con la crisis social evidenciada por brechas más amplias entre ricos y pobres, desempleo, violaciones de derechos humanos, entre otros aspectos, han llevado al cuestionamiento respecto a la responsabilidad de las empresas en las crisis socioambientales. En la última reunión sobre cambio climático COP 26, los jefes de estado al unísono coincidieron en la gravedad de la crisis climática y la responsabilidad histórica de encaminar al mundo para enfrentar este urgente desafío. Lo anterior lleva a las empresas a prestar atención a otros aspectos más allá de la generación de benefic…
STUDIO NUMERICO-SPERIMENTALE DI GIUNZIONI IBRIDE A DOPPIA SOVRAPPOSIZIONE CFRP-ALLUMINIO
2013
The adhesively bonded joints and the mechanical joints between structural components made by composite materials or between elements made by composite and metal, are commonly used in different fields of modern industrial design and manufacturing, since they are characterized by economy, reliability and ease of assembly. The bonded joints are characterized by high stiffness and fatigue life, although delamination phenomena localized near the edges of attack of the adherends may limit their use, especially in particular applications where corrosive environments and humidity can lead to premature failure. In these cases, a possible alternative is offered by the well known riveted joints. On th…
Antimicrobial and antioxidant supramolecular ionic liquid gels from biopolymer mixtures
2023
In this work, we describe the preparation and characterization of supramolecular ionic liquid gels based on binary mixtures of biopolymers, comprising chitosan, chitin, cellulose and lignin. The gels were obtained in ionic liquids differing in the cation or the anion, with no need for a cross-linking agent or acid treatment. The materials obtained were characterized for the minimum gelation concentration, porosity, swelling and rheological properties, finding a prominent influence of the nature of the ionic liquid anion. Then, we investigated the ability of the gels to scavenge free radicals, finding that the gels exhibit a higher antioxidant ability than their individual components. Moreov…
Le malte idrauliche dell’Acquedotto Romano di Termini Imerese
2009
Aim of this paper is the characterization of ancient hydraulic mortars from the roman water supply system of Thermae (I-II cent. A.D.), known as “Aqua Cornelia” and "Figurella" aqueducts, more than 10 kilometers long. Because of malfunctioning of the "Barratina" siphon, major changes in the original adduction system were realized in several steps. Mortar samples were taken from both channels lining materials and structural elements, in order to contribute to answer some questions about the construction phases of the aqueduct. The materials characterization was performed by means of XRD analysis, optical microscopy, microRaman spectroscopy and simultaneous thermal analysis. The latter is a u…
La centrale elettrica Alessandro Volta. Conoscenza, recupero compatibile e pratiche di rigenerazione di un tassello di Patrimonio industriale a Paler…
2022
Palermo annovera un esempio di archeologia industriale lungo il waterfront davvero emblematico nell'ottica del riuso adattivo, delle buone pratiche di recupero compatibile e di rigenerazione dello spazio urbano: si tratta della Centrale elettrica Alessandro Volta, costruita dalla Schuckert & Co. di Norimberga nel 1899. Informazioni documentarie-archivistico-iconografiche reperite, nonché la permanenza pressoché immutata di alcuni corpi di fabbrica originari, consentono di attivare una ricerca applicata e progetto, ispirati ai suggerimenti della committente, agli indirizzi progettuali dell'Autorità portuale per la riqualificazione del waterfront, alle stringenti priorità europee in termi…