1,720,975 research outputs found
Investigating the degradation phenomena of Teflon exposed to acidic environment
No full textThis study provides an overview of the effects of prolonged acid attack on the surface of PTFE gaskets, assessed using Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The PTFE analysed originates from two manufacturers in form of Teflon adhesive tapes, used as gaskets in an ultrasonic tyre moulds cleaning plant (UMCS). The gaskets were exposed to various acid baths, temperature and ultrasonic waves, and shown anomalous damage and surface degradation in a relatively short operation time. The analyses here reported have been aimed at investigating this unusual behaviour. PTFE samples have been treated with different acid mixes to evaluate possible different aging effects. Both surface and core have been analysed after aging, providing evidence of the degradation phenomena. In particular, different acid treatments have highlighted different response of PTFE and differences among manufacturers
Impianto e metodo per il recupero di fibre di carbonio o di vetro da materiali compositi
No full textUn impianto (1) per il recupero di fibre di carbonio o di vetro da materiali compositi comprendenti dette fibre in una matrice polimerica comprende un forno a tunnel (2) lungo il quale detti materiali vengono trasportati all’interno di contenitori (6), in cui detto forno a tunnel comprende una zona di pirolisi (3), nella quale detti materiali compositi sono assoggettati a un processo di pirolisi in un’atmosfera priva di ossigeno, una zona di gassificazione (3) nella quale detti materiali sono sottoposti a un processo di combustione in presenza di ossigeno, e una zona intermedia di separazione (5), posta tra la zona di pirolisi (3) e la zona di gassificazione (4), nella quale è prevista una pluralità secondi dispositivi iniettori (23) per immettere azoto in detta zona intermedia (5), in modo da impedire che l’atmosfera della zona di pirolisi (2) entri in contatto con l’atmosfera della zona di gassificazione (3)
Installation and method for recovering carbon or glass fibres from composite materials
No full textL’invenzione riguarda un impianto e un metodo per il recupero di fibre di
carbonio o di vetro da materiali compositi nei quali dette fibre sono racchiuse in una
matrice polimerica.
suddetti materiali compositi possono provenire da scarti prodotti in diversi stadi
di lavorazione industriale e/o da manufatti giunti al termine del loro ciclo di vita
Validation of carbon fibers recycling by pyro-gasification: The influence of oxidation conditions to obtain clean fibers and promote fiber/matrix adhesion in epoxy composites
Full text linkThis work aims at demonstrating, at a pilot plant scale, the potential of the pyro-gasification process to produce carbon fibers (CF) as secondary raw materials. The solid residue obtained upon pyrolysis of CFRP was characterized and oxidized, applying different process conditions to provide clean fibers. The same process was applied to virgin fibers, thus highlighting the protective action that char provides to CF during the oxidation step. The recovered fibers were used to produce new short fiber composites which, upon optimization of the mixing and curing conditions, were competitive with the performance of pristine fibers composites. Indeed, the oxidation leaves an oxygen rich surface which positively interacts with the epoxy resin, thus promoting adhesion without the requirement of an additional sizing process after the CFs recycling. These results provided sufficient validation of the recovered CF quality, thus leading to the scale up of the process to produce an integrated pyro-gasification semi—industrial plant
Dispersion and evaluation of organically modified nanoclays as performance enabling fillers for pPVC synthetic leathers
No full textNanoclays (NCs), both organically modified (OMNCs) and purely inorganic, have been evaluated as performance enabling fillers for innovative and high-performance plasticized PVC (pPVC) synthetic leathers (SLs). First, a novel dispersion technology for nanoclays in plastisols has been developed and tuned, modifying and improving different procedures used in Vulcaflex SpA. Secondly, pPVC foils containing three different NCs have been prepared and tested for mechanical, thermal and flame, and anti-migration properties using both standard and internal methods. Results have been compared to those of a neat pPVC foil and, due to the expected flame retardancy improvements, of a foil containing 2 phr of antimony trioxide (ATO). Even though certain properties appear to be slightly improved, the overall performance of these NCs are not completely satisfying
Evaluation of antimony-free flame retardants for pPVC synthetic leathers intended for safer automotive interiors
No full textAntimony-based compounds have been the state-of-the-art flame retardants (FRs) for plasticized PVC (pPVC) due to their superior efficiency at very low loading. However, the use of antimony compounds poses more than an issue, for both human health and the environment, related to their extraction, processing and use. In order to follow the consequent need to phase out antimony compounds, different FRs for high-performance plasticized PVC (pPVC) synthetic leathers (SLs), intended for automotive interiors applications, have been selected amongst readily available on the market additives and tested in highly plasticized formulations. These FRs have been evaluated either alone or in combination in order to ascertain possible synergistic effects. The samples have been obtained with standard procedures used in the R&D laboratory of Vulcaflex S.p.A., and tested for thermal stability, mechanical and flame resistance, following standard and internal methods. Results have been then compared to those of a neat pPVC foil (DUP) and of a foil containing 2 phr of antimony trioxide (ATO). Amongst the alternatives tested, various combinations proved effective in improve flame retardancy without negatively affecting mechanical properties, and proving to be, thus, promising candidates to substitute ATO as FRs in pPVC materials
Impianto pilota per la pirolisi di PFU: ottimizzazione dei parametri di processo, studio e caratterizzazione dei prodotti ottenuti
Full text linkIn questo lavoro sono descritte le attività svolte a partire dal primo avviamento dell’impianto pilota di pirolisi di pneumatici, le ottimizzazioni impiantistiche e di processo effettuate, la caratterizzazione dei materiali di partenza e dei prodotti. Particolare attenzione è stata posta alla variabilità dei prodotti in uscita in funzione di parametri di processo quali operazioni preliminari, temperatura, pressione, quantità di materiale trattato e tempo di residenza, allo scopo di ottimizzare il processo e individuare le condizioni per l’ottenimento di specifici prodotti a livello quali- e quantitativo
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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