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A Comprehensive Study of Fly Ash Based Geopolymers Activated at Room TemperatureNatali, Maria Elia <1984> January 1900 (has links)
This research presents the overall results obtained by investigating the performances of fly ash based geopolymers activated at room temperature. Several characterization tests have been perfomed, starting from a deep understanding of the raw materials, in view of finding alternative solutions to the use of traditional hydraulic binders or ceramic materials via alkali-activation. Different types of geopolymer samples (i.e., pastes, mortars and reinforced mortars) have been formulated by varying the nominal Na2O/SiO2 molar ratio in the activating solutions (and in a specific case the curing conditions) and their chemical, physical, mechanical and microstructural performances have been evaluated comparing the results obtained by using different types of precursors and by a traditional cement-based binder. Specific attention has ben focused on durability issues such as high temperature applications and corrosion resistance of the embedded rebars in geopolymer mortars exposed to aggressive environments. Alkali-activation has been found to represent a valid approach in developing performant cement-free products but step forward are needed in order to optimize the solution chemistry and enhance physical and mechanical properties starting from a deep understand at nanoscale of the geopolymerization reaction mechanisms.
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New Phosphate-Based Treatments for Carbonate Stone Consolidation and ProtectionGraziani, Gabriela <1986> January 1900 (has links)
Carbonate stones on site undergo severe weathering processes, that make consolidation and protection necessary. However, currently available consolidants and protectives are far from being satisfactory when applied to this kind of materials. For this reason, in this thesis an innovative hydroxyapatite-based treatment was developed for limestone consolidation, marble consolidation and marble protection.
Firstly, a new treatment protocol was set up for limestone and marble consolidation: solution precursor, concentration and pH, application method and possible additions were investigated to improve the treatment performance. Then, efficacy, compatibility and durability of the treatment were evaluated on these two lithotypes, in comparison with the products currently used for the same aim (ethyl silicate and ammonium oxalate). For marble, the treatment protocol developed in laboratory was also tested on a real historic artefact and on site.
Moreover, a surface treatment for protecting marble against acidic rain was formulated, investigating how different parameters (starting solution pH and concentration, organic and inorganic additions) affect the morphology, composition and acid resistance of the treated surface.
Excellent results were achieved: hydroxyapatite resulted an effective, compatible and durable consolidant for carbonate stone. Moreover, ethanol addition allowed to obtain a uniform, acid resistant protective hydroxyapatite layer on marble.
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Le piastrelle di ceramica per locali di preparazione e lavorazione di prodotti alimentari. Sviluppo di speciali metodi di caratterizzazione e previsione delle prestazioniMalavasi, Paolo <1968> 23 May 2007 (has links)
No description available.
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Emissione di sostanze organiche volatili (SOV) provenienti dalla cottura di piastrelle ceramiche. Studio delle relazioni fra additivi organici, condizioni di cottura ed emissione di SOVMarino, Luis Fernando Bruno <1967> 23 May 2007 (has links)
No description available.
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La matematica fuzzy nell'ingegneria dei materiali. Applicazioni alla durevolezza e alla conservazione dei materiali in opera nei siti archeologiciSpanu, Nannina <1975> 23 May 2007 (has links)
La ricerca presentata è un’ampia esplorazione delle possibili applicazioni di concetti, metodi
e procedure della Fuzzy Logic all’Ingegneria dei Materiali.
Tale nuovo approccio è giustificato dalla inadeguatezza dei risultati conseguiti con i soli
metodi tradizionali riguardo alla reologia ed alla durabilità, all’utilizzo di dati di laboratorio
nella progettazione e alla necessità di usare un linguaggio (informatizzabile) che consenta una
valutazione congiunta degli aspetti tecnici, culturali, economici, paesaggistici della
progettazione.
– In particolare, la Fuzzy Logic permette di affrontare in modo razionale l’aleatorietà delle
variabili e dei dati che, nel settore specifico dei materiali in opera nel costruito dei Beni
Culturali, non possono essere trattati con i metodi statistici ordinari.
– La scelta di concentrare l’attenzione su materiali e strutture in opera in siti archeologici
discende non solo dall’interesse culturale ed economico connesso ai sempre più numerosi
interventi in questo nuovo settore di pertinenza dell’Ingegneria dei Materiali, ma anche dal
fatto che, in tali contesti, i termini della rappresentatività dei campionamenti, della
complessità delle interazioni tra le variabili (fisiche e non), del tempo e quindi della
durabilità sono evidenti ed esasperati.
– Nell’ambito di questa ricerca si è anche condotto un ampio lavoro sperimentale di
laboratorio per l’acquisizione dei dati utilizzati nelle procedure di modellazione fuzzy (fuzzy
modeling). In tali situazioni si è operato secondo protocolli sperimentali standard:
acquisizione della composizione mineralogica tramite diffrazione di raggi X (XRD),
definizione della tessitura microstrutturale con osservazioni microscopiche (OM, SEM) e
porosimetria tramite intrusione forzata di mercurio (MIP), determinazioni fisiche quali la
velocità di propagazione degli ultrasuoni e rotoviscosimetria, misure tecnologiche di
resistenza meccanica a compressione uniassiale, lavorabilità, ecc.
– Nell’elaborazione dei dati e nella modellazione in termini fuzzy, la ricerca è articolata su tre
livelli:
a. quello dei singoli fenomeni chimico-fisici, di natura complessa, che non hanno trovato,
a tutt’oggi, una trattazione soddisfacente e di generale consenso; le applicazioni
riguardano la reologia delle dispersioni ad alto tenore di solido in acqua (calci, cementi,
malte, calcestruzzi SCC), la correlazione della resistenza a compressione, la gelività dei
materiali porosi ed alcuni aspetti della durabilità del calcestruzzo armato;
b. quello della modellazione della durabilità dei materiali alla scala del sito archeologico; le
applicazioni presentate riguardano i centri di cultura nuragica di Su Monte-Sorradile,
GennaMaria-Villanovaforru e Is Paras-Isili;
c. quello della scelta strategica costituita dalla selezione del miglior progetto di
conservazione considerando gli aspetti connessi all’Ingegneria dei Materiali
congiuntamente a quelli culturali, paesaggistici ed economici; le applicazioni hanno
riguardato due importanti monumenti (Anfiteatro e Terme a Mare) del sito Romano di
Nora-Pula.
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Functional ceramic foams from preceramic polymersBiasetto, Lisa <1977> 23 May 2007 (has links)
No description available.
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Progettazione di nuovi biomateriali a base poliestereaFoltran, Ismaela <1974> 15 June 2007 (has links)
No description available.
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Optically active photoresponsive multifunctional polymeric materialsMauriello, Francesco <1980> 20 May 2008 (has links)
In the last year [1], Angiolini and co-workers have synthesized and investigated
methacrylic polymers bearing in the side chain the chiral cyclic (S)-3-hydroxypyrrolidine
moiety interposed between the main chain and the trans-azoaromatic chromophore,
substituted or not in the 4’ position by an electron-withdrawing group. In these materials, the
presence of a rigid chiral moiety of one prevailing absolute configuration favours the
establishment of a chiral conformation of one prevailing helical handedness, at least within
chain segments of the macromolecules, which can be observed by circular dichroism (CD).
The simultaneous presence of the azoaromatic and chiral functionalities allows the polymers
to display both the properties typical of dissymmetric systems (optical activity, exciton
splitting of dichroic absorptions), as well as the features typical of photochromic materials
(photorefractivity, photoresponsiveness, NLO properties).
The first part of this research was to synthesize analogue homopolymers and copolymers
based on bisazoaromatic moiety and compare their properties to those of the above mentioned
analogue derivatives bearing only one azoaromatic chromophore in the side chain. We
focused also the attention on the effects induced on the thermal and chiroptical behaviours by
the insertion of particulars achiral comonomers characterized by different side-chain mobility
and grown hindrance (MMA, tert-BMA and TrMA).
On the other hand carbazole containing polymers [2] have attracted much attention
because of their unique features. The use of these materials in advanced micro- and
nanotechnologies spreads in many different applications such as photoconductive and
photorefractive polymers, electroluminescent devices, programmable optical
interconnections, data storage, chemical photoreceptors, NLO, surface relief gratings, blue
emitting materials and holographic memory.
The second part of the work was focused on the synthesis and the characterization polymeric
derivatives bearing in the side chain carbazole or phenylcarbazole moieties linked to the (S)-
2-hydroxy succinimide or the (S)-3-hydroxy pyrrolidinyl ring as chiral groups covalently
linked to the main chain through ester bonds.
The last objective of this research was to design, synthesize, and characterize multifunctional
methacrylic homopolymers and copolymers bearing three distinct functional groups (i.e.
azoaromatic, carbazole and chiral group of one single configuration) directly linked in the
side chain.
This polymeric derivatives could be of potential interest for several advanced application
fields, such as optical storage, waveguides, chiroptical switches, chemical photoreceptors,
NLO, surface relief gratings, photoconductive materials, etc.
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Sintesi e proprietà di nuovi materiali polimerici a base tiofenica per applicazioni innovativeCesari, Gaia <1981> 20 May 2008 (has links)
No description available.
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Realizzazione di riporti funzionalizzanti su superfici ceramiche per la produzione di energia elettrica mediante effetto fotovoltaicoFazio, Sandra <1974> 29 May 2008 (has links)
This research, carried out during the PhD in Materials Engineering, deals with the
creation of layers, with different functionality, deposited on a ceramic substrate, to obtain
photovoltaic cells for electricity production.
The research activities are included in the project PRRIITT, Measure 4 (Development of
Networks), Action A (Research and Technology Transfer Laboratories), Thematic reference 3
(Advanced materials applications development), co-financed by the Emilia Romagna Region,
for the creation of CECERBENCH laboratory, which aims to develop "Tiles with a
functionalised surface”.
The innovation lies in the study of materials and in the development of technologies to
achieve a "photovoltaic surface", directly in the tiles production process. The goal is to
preserve the technical characteristics, and to make available new surfaces, exploiting
renewable energy sources. The realization of Building Integrated PhotoVoltaic (BIPV) is
nowadays a more and more spread tendency.
The aims of the research are essentially linked to the need to diversify the actual ceramic tile
production (which is strongly present in the Emilia Romagna Region ), and to provide a
higher added value to the tiles.
Solar energy production is the primary objective of the functionalization, and has a relevant
ecological impact, taking into account the overwhelming global energy demand.
The specific activities of the PhD were carried out according to the achievement of scientific
and technological objectives of CECERBENCH laboratory, and involved the collaboration in
design solutions, to obtain the cells directly on the tiles surface. The author has managed
personally a part of the research project.
Layers with different features were made:
- Electrically conductive layers, directly on the ceramic tiles surface;
- Layers to obtain the photovoltaic functionality;
- Electrically insulating, protective layers (double function).
For each layer, the most suitable materials have been selected. Among the technical
application, the screen printing was used. This technique, widely used in ceramics, has many
application areas, including the electronics and photovoltaic industries. It is an inexpensive
technique, easy to use in industrial production lines.
The screen printing technique was therefore studied in depth by theoretical
considerations, and through the use of rheological measurements.
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