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La tesi si pone l'obiettivo di studiare le proprietà ottiche degli Xeni. Gli Xeni, reticoli monoelementali artificiali simili al grafene, hanno mostrato sin dalla loro scoperta grandi potenzialità per applicazioni negli ambiti dell'elettronica e della fotonica. Purtroppo, il loro utilizzo è ancora limitato dall'elevata reattività chimica e dai forti effetti di ibridazione con i substrati nativi. Conoscere la risposta ottica o termo-ottica degli Xeni, escludendo o controllando eventuali effetti del substrato, è quindi funzionale allo sviluppo di nuove tecnologie. La ricerca è stata condotta nell'ambito del progetto X-Fab (ERC COG Grant n. 772261), presso i laboratori CNR-IMM di Agrate Brianza. In questo studio vengono esaminate diverse configurazioni a base di Xene, combinando tecniche di analisi in situ (XPS e LEED) e di spettroscopia ottica (FTIR, Vis-UV e Raman), con lo scopo di determinarne la risposta ottica e valutare l'integrazione degli Xeni in un dispositivo che ne sfrutti le potenzialità. La prima configurazione analizzata prevede l'introduzione di un substrato isolante e otticamente trasparente, come lo zaffiro, a sostituzione del più diffuso argento. Lo zaffiro, nella sua orientazione (0001) presenta un reticolo a simmetria esagonale commensurato a quello di silicene e stanene. La conducibilità ottica di nano-film di stagno cresciuti tramite MBE è stata ricavata da misure di trasmittanza e riflettanza, acquisite tra 0.01 e 6.5 eV. L'analisi spettrale e il successivo confronto con dati teorici già presenti in letteratura hanno permesso di identificare delle caratteristiche non banali, in parte riconducibili allo stanene. L'analisi chimica eseguita in situ durante la crescita ha però evidenziato anche la presenza di una componente dello stagno ossidata dovuta ad effetti del substrato. Il problema emerso è stato affrontato introducendo uno strato di grafene tra i film di stagno e l'Al2O3. L'introduzione dello strato di grafene ha permesso di evitare l'ossidazione dello stagno, come confermato dall'analisi XPS. I risultati emersi dall'analisi ottica supportano invece la possibilità di stabilizzare la fase α dello stagno a temperatura ambiente proprio grazie all'introduzione dello strato di grafene. In modo concettualmente simile a quanto fatto per il film sottili di stagno con il grafene, è stata valutata la possibilità di disaccoppiare il silicene dall'argento introducendo tra i due materiali uno strato di silicene. La risposta ottica del silicene epitassiale è stata studiata attraverso la spettroscopia Raman opto-termica e con misure di riflettanza ottica. I risultati ottenuti supportano l'efficacia dello strato di stanene nel rompere l'interazione tra silicene e substrato d'argento. Inoltre, sebbene si tratti di una valutazione indiretta della risposta termica, i risultati ottenuti dall’analisi Raman aprono la strada alla determinazione delle proprietà termiche del silicene supportato. Esperimenti svolti su nano-film di silicio cresciuti epitassialmente su zaffiro hanno evidenziato un comportamento della conducibilità ottica riconducibile alla presenza di elettroni di Dirac come ci si aspetta per il silicene. Sulla base di questi risultati, la configurazione Xene-su-Al2O3 è stata sfruttata per valutare l'integrabilità degli Xeni in un dispositivo che permettesse di osservare sperimentalmente la risposta plasmonica di questi materiali. Sono stati fatti dei test di trasferimento tecnologico sulla piattaforma Xene-su-Al2O3, realizzando reticoli periodici con fotolitografia ottica e implementando un sistema di top gating a base di liquido ionico. Nonostante gli esperimenti non abbiano portato alla realizzazione di un dispositivo funzionante, i punti critici emersi dimostrano che il margine per ottenere miglioramenti è ancora ampio. The aim of this thesis is to investigate the optical properties of Xenes. Since their discovery, Xenes, artificial graphene-like single-element lattices, have shown great potential for applications in electronics and photonics. Unfortunately, their use is still limited by their high chemical reactivity and strong hybridisation effects with native substrates. Understanding the optical or thermo-optical response of Xenes, and thus excluding or controlling possible substrate effects, is therefore crucial for the development of new technologies. The research was carried out as part of the X-Fab (ERC COG Grant n. 772261) project at the CNR-IMM laboratories in Agrate Brianza. In this study, several Xenes-based configurations are investigated using a combination of in situ analysis (XPS and LEED) and optical spectroscopy (FTIR, Vis-UV and Raman) techniques to determine their optical response and evaluate the integration of Xenes into a device that exploits their potential. The first configuration analyzed involved the introduction of an insulating and optically transparent substrate, such as sapphire (Al2O3), to replace the more common silver. Sapphire, in its (0001) orientation, has a hexagonal symmetry lattice commensurate to that of silicene and stanene. The optical conductivity of tin nano-sheets grown by MBE was derived from transmittance and reflectance measurements. The measurements were carried out covering a range from 0.01 to 6.5 eV. Spectral analysis and subsequent comparison with theoretical data from the literature made it possible to identify non-trivial features, some of which can be attributed to stanene. However, in situ chemical analysis during growth also revealed the presence of an oxidised tin component due to substrate effects. This issue was solved by introducing a graphene layer between the tin films and Al2O3. The introduction of the graphene layer prevented oxidation of the tin, as confirmed by XPS analysis. The results of the optical analysis, on the other hand, support the possibility of stabilising the α phase of tin at room temperature by introducing the graphene buffer layer. The possibility of decoupling silicene from silver by introducing a layer of stanene between the two materials was evaluated. The optical response of the epitaxial silicene was studied using opto-thermal Raman spectroscopy and optical reflectance measurements. The results support the effectiveness of the stanene layer in breaking the interaction between silicene and the silver substrate. Furthermore, although this is an indirect evaluation of the thermal response, the results obtained from the Raman analysis pave the way to the determination of the thermal properties of the supported silicene. Previous experiments on silicon nano-sheets epitaxially grown on sapphire showed signature of graphene-like behavior in the low-energy optical conductivity. The Dirac-like electrodynamics is expected from the band structure of silicene. Based on these results, the Xene-on-Al2O3 configuration was used to evaluate the integrability of Xenes in a device that would allow the observation of the Dirac plasmonic response of these materials. Technology transfer tests were carried out on the Xene-on-Al2O3 platform by realizing periodic patterns using optical photolithography and implementing an ionic liquid-based top gating system. The experiments did not result in a working device. However, the critical points that emerged show that there is still plenty of room for improvement.

In this work, polyurethane (PU) insulating panels containing different amounts of a microencapsulated paraffin with a nominal melting temperature of 24 °C, used as phase change material (PCM), were produced. The resulting panels behaved as multifunctional materials able to thermally insulate and simultaneously storing/releasing thermal energy near room temperature. The panels were characterized from a microstructural, thermal and mechanical point of view. Viscosity measurements highlighted an increase in the viscosity values of the PU liquid precursors due to the addition of the capsules, and this could lead to some difficulties during the production stages, especially in the mixing and foaming phases. From optical microscopy micrographs and density measurements, it was observed that the introduction of paraffin tended to destroy the cellular structure of PU foams, and for PCM contents above 30 mass/% the foams were characterized by an open-cell morphology. SEM observations showed that PCM was preferentially distributed in the cell walls intersection, and a rather limited interfacial adhesion between capsules and PU could be detected. Thermogravimetric analysis evidenced that the introduction of the PCM tended to increase the degradation resistance of the foams, while from differential scanning calorimetry tests it was possible to conclude that PCM addition was able to impart good thermal energy storage properties to the foams, with specific melting enthalpy values of 70 J g−1 for a microcapsules concentration of 50 mass/%. As expected, thermal conductivity (λ) of the foams increased with PCM amount, but this enhancement was not directly related to the higher λ of the PCM itself, but rather than to the cell opening effect promoted by the PCM introduction. The microcapsules addition progressively increased the stiffness of the foams, reducing the failure properties both under quasi-static and impact conditions. Moreover, the mechanical properties were strongly affected by the testing temperature (i.e. the physical state of the wax contained in the microcapsules).

To develop an activebiopolymerfilm based on chitosan, sodium caseinate, and rosemary essential oil (REO), the objective of this work was to investigate the effect of REO on the structure and physical properties of biopolymer films.Fourier transform infrared spectroscopywas conducted for fingerprinting to identify the REO addition. The thermal behaviour of each film was investigated using athermogravimetric analysis. Furthermore, the optical properties, surfacehydrophobicity, solubility, mechanical properties, and water vapour permeability were investigated. The results showed that the presence of REO changes the structural organisation of the blended sodium caseinate and chitosan film, thereby inducing an increase in the surface hydrophilicity of the film. However, the solubility and water vapour permeability of the film were not affected by the structural modification induced by REO. Moreover, a mild effect of the REO on the mechanical properties of the sodium caseinate/chitosan film was observed. A thermal analysis confirmed that the incorporation of REO did not influence the degradation temperature of the films. Overall this studying has demonstrated that caseinate/chitosan film enriched in REO, related to his thermal and chemico physical properties can be applied for food packaging application.

Plastic has become an essential part of our modern lifestyle and its global diffusion has led to a significant increase in the production of related waste, with obvious repercussions on the environment and on the entire sustainability chain. Recycling this kind of materials in the field of civil and industrial engineering is considered an ecological and economical solution due to the advantages it can offer. This paper represents the results of experimental investigations of mechanical strength, hygro-thermal and durability properties of two kinds of products: urban tiles (90 % PVC powder and 10 % polyurethane resin) and cement-based mortars reinforced with PVC compound coming out of electric cable protective sheath. The manufactured mortars were obtained by the volumetric substitution of the sand with five different percentages of plastic waste, from 10 % to 50 %. Plastic aggregates reduce density, causing a decrease in flexural and compressive strength of mortars. Nevertheless, the presence of plastic aggregate leads to a significant improvement of thermal insulation and shows a greater resistance to capillary water absorption compared to the reference one. The mechanical tests after two different cycles of accelerated solar aging of urban tiles demonstrated the feasibility of its use for external flooring (green parking). These results foster future studies about the development of increasingly eco-sustainable building materials.

Among the several actions contributing to the development of a sustainable society, there is the eco-design of new plastic materials with zero environmental impact but that are possibly characterized by properties comparable to those of the traditional fossil-based plastics. This action is particularly urgent for food packaging sector, which involves large volumes of plastic products that quickly become waste. This work aims to contribute to the achievement of this important goal, proposing new bio-based cycloaliphatic polymers based on trans-1,4-cyclohexanedicarboxylic acid and containing different amount of camphoric acid (from 0 to 15 mol %), a cheap and bio-based building block. Such chemical modification was conducted in the melt by avoiding the use of solvents. The so-obtained polymers were processed in the form of films by compression molding. Afterwards, the new and successfully synthesized random copolymers were characterized by molecular (NMR spectroscopy and GPC analysis), thermal (DSC and TGA analyses), diffractometric (wide angle X-ray scattering), mechanical (through tensile tests), and O2 and CO2 barrier point of view together with the parent homopolymer. The article aims to relate the results obtained with the amount of camphoric moiety introduced and to present, the different microstructure in the copolymers in more detail, indeed, in these samples, a different crystalline form developed (the so-called β-PBCE). This latter form was the kinetically favored and less packed one, as proven by the lower equilibrium melting temperature determined for the first time by Baur’s equation.

Polyhedral oligomeric silsesquioxanes (POSSs), with Si vertices interconnected by –O– linkages, form three-dimensional nanometer size cage structures with substituents attached to silicon atoms. These substituents may contain reactive groups, such as hydroxyl or isocyanate. A combination of a rigid inorganic nanocore with organic vertex groups makes POSS molecules useful hybrid building blocks that can be chemically incorporated in the polymer matrix by copolymerization, grafting or reactive blending, or physically mixed by solvent casting or polymer processing by using, for example, the extrusion technique [1]. The use of POSSs for making polymer composites has grown exponentially since the last few years of the 20th century. In comparison with the other most commonly used fillers, POSSs possess the advantage of being molecules. Thus, this allows us to combine their nano-sized cage structures, which have dimensions that are similar to those of most polymer segments and produce a particular and exclusive chemical composition. These characteristics linked with their hybrid (inorganic–organic) nature allow researchers to modify POSS according to particular needs or original ideas, before incorporating them into polymers [2]. Figure 1. Molecular structure of the prepared and investigated POSSs In this context, our research group at the University of Catania, in collaboration with eminent researchers in the field, tested the stabilization of different polymers, synthetics or naturals, such as polyethersulfone (PES), ethylene propylene diene monomer (EPDM), polyethylene oxide (PEO), and chitosan by the incorporation of polyhedral oligomeric silsesquioxanes (POSS) molecules [3-6]. Represented in their most common form by the symbol T8 and having a diameter usually falling in the range of 1.5–3 nm, POSS molecules comprise a silicon and oxygen cage completed by organic groups that are covalently bonded with silicon atoms. Novel architectures of POSS with various organic groups were synthesized by using corner capping reaction in order to verify their polimeryzability in the presence of monomer. In this work, after a spectroscopic investigation aiming at verify that the obtained molecules have the structure for which they were designed, their thermal behavior in terms of resistance to thermal degradation were evaluated by means of thermogravimetric analysis (TGA). The obtained temperatures at 5% mass loss (T5%) were compared with each other and with those of the POSSs previously designed and studied by us. Bibliography [1] Lichtenhan, J.D., Pielichowski, K., Blanco, I. POSS-Based Polymers. Polymers 2019, 11, 1727 [2] Blanco, I. The Rediscovery of POSS: A Molecule Rather than a Filler. Polymers 2018, 10, 904. [3] Cicala, G., Blanco, I., Latteri, A., Ognibene, G., Agatino Bottino, F., Fragalà, M.E. PES/POSS Soluble Veils as Advanced Modifiers for Multifunctional Fiber Reinforced Composites. Polymers 2017, 9, 281 [4] Zaharescu, T., Blanco, I., Bottino, F.A. Antioxidant activity assisted by modified particle surface in POSS/EPDM hybrids. Appl. Surf. Sci. 2020, 509, 144702 [5] Legnani, L.; Iannazzo, D.; Pistone, A.; Celesti, C.; Giofrè, S.; Romeo, R.; Di Pietro, A.; Visalli, G.; Fresta, M.; Bottino, P.; et al. Functionalized polyhedral oligosilsesquioxane (POSS) based composites for bone tissue engineering: Synthesis, computational and biological studies. RSC Adv. 2020, 10, 11325–11334 [6] Stipanelov Vrandečić, N., Erceg, M., Andričić, B., Blanco, I., Bottino, F.A. Characterization of poly(ethylene oxide) modified with different phenyl hepta isobutyl polyhedral oligomeric silsesquioxanes. J. Therm. Anal. Calorim. 2020, 142, 1863–1875

Increasing concerns about climate change and global warming bring about technical steps for the development of several energy-efficient technologies. Since the building sector is one of the largest energy users for cooling and heating necessities, the incorporation of a proper energy-efficient material into the building envelopes could be an interesting solution for saving energy. Phase change material (PCM)-based thermal energy storage (TES) seems suitable to provide efficient energy redistribution. This is possible because the PCM is able to store and release its latent heat during the phase change processes that occurs according to the environmental temperature. The purpose of this paper was the characterization of the thermal properties of a composite PCM (i.e., Lecce stone/poly-ethylene glycol, previously developed) incorporated into mortar compositions based on different binders (i.e., hydraulic lime and cement). The study was carried out using an experimental set up through which it was possible to simulate the different seasons of the years. It was observed that the addition of PCM in mortars leads to a decrease of the maximum temperatures and increase of the minimum temperatures. Furthermore, the results shown a reduction of the heating and cooling needs, thus confirming the capability of this material to save energy.

Lignocellulosic raw materials are being utilised in many industrial sectors as a natural source of interesting biopolymers. In the present research, tomato plant agri-waste, were subjected to an enzymatic treatment (pectinase, hemicellulase, xylanase and laccase) with the aim of recovering polymeric matrices contained therein and obtain a good quality fibre. The cellulose content in the enzyme-treated fibres was enriched of 25% compared to the untreated, and a fair reduction in hemicellulose and lignin was registered. Morphological analyses at SEM demonstrated the cleanliness and fibrillation of fibres. Moreover, the thermal profile, water absorption and pulp viscosity of fibres was strongly affected by the composition changes. The paperboard manufactured from an enzymatically treated sample showed increased stiffness when subjected to tensile testing respect to the control. Therefore, the use of enzyme in fibre pulping has a potential application in the design of sustainable materials.

Novel A-B-A triblock copolymers based on poly(L-lactic acid) (PLLA) were designed with an ad hoc chemical structure to prepare micro- and nanoparticles for controlled drug delivery. A block is formed by PLLA, while central B block is a copolymeric system based on poly(butylene succinate) and poly(triethylene succinate): more specifically, two copolymers with fix composition (50:50 mol:mol) and different molecular architecture were synthesized. One of them is characterized by a block architecture, i.e. long butylene succinate and triethylene succinate sequences form the macromolecular chains, the other being on the contrary a random copolymer with short sequences. The so-obtained materials were characterized from the molecular and thermal point of view. Moreover, to investigate the effect of both chemical structure and molecular architecture of the polymers synthesized on drug release kinetics, Dexamethasone-encapsulated micro- and nanoparticles were prepared by oil-in-water miniemulsion technique. These particles were subjected to thermal and morphological characterization. After that, drug release studies were carried out, and the effect of chemical composition, sequence distribution and particle size on release profile was evaluated. (C) 2020 Elsevier Ltd. All rights reserved.

Potatoes tubers are the raw materials of many processed food, such as cooked potatoes in hot water, baked potatoes and the most popular fried potatoes. The objective of this work was to study the impact of boiling, baking and frying on microstructure and properties of six potato varieties (Agata, Agria, Innovator, Lady Rosetta, Musica and Spunta) with different origin. Scanning Electron Microscopy revealed significant differences between varieties and tuber microstructure changes following all cooking processes. Differential Scanning Calorimeter analysis showed that the transition temperatures (ranging between 60 °C and 85 °C) and enthalpies of gelatinization (2.1 J/g–3.9 J/g) of tubers were also variety dependent. In addition, the elasticity modulus of cooked samples depended on process type and followed the order: baked potatoes > boiled > fried potatoes. In particular, baked Lady Rosetta (224.3 kPa) showed the least decrease in rigidity between thermal processes. Fried Agria and Spunta, (56.3 and 61 kPa, respectively) had the smallest value of Young's modulus. Molecular marker analyses provided a genetic fingerprinting of our varieties, allowing the identification of diagnostic markers. Innovator revealed an important genetic distance from the other varieties. Such distance corresponded to its exclusive phenotypic traits, that are known to affect thermochemical properties. The information obtained in this work may be useful to further study and associate genetic sequences with appreciable food technological traits.

We present a two-step process to obtain PMMA fibrous membranes with homogeneously in situ synthesized zinc oxide nanoparticles of defined shape and size, both on the fibers' surface and bulk. The method is based on the electrospinning of PMMA/precursor solutions and the subsequent thermally activated in situ conversion of zinc acetate to zinc oxide nanoparticles directly in the solid polymeric fibers. X-ray diffraction measurements ensure the formation of crystalline ZnO nanoparticles. Scanning and transmission electron microscopy prove that homogeneously distributed nanoparticles with two different morphologies and size distributions are obtained, depending on the area of the fibers where the nanoparticles are nucleated and on the initial precursor's content. In particular, branched nanoparticles homogeneously decorate the fibers' surface with their dimensions that range from 50 nm to 140 nm for initial precursor contents from 23 to 40 wt%, respectively. On the other hand, small spherical nanoparticles of ca. 7 nm are mainly observed in the bulk of the fibers. Unlike the branched nanoparticles, the dimensions of the spherical nanoparticles are practically unaffected by the precursor amount initially loaded. The homogeneously distributed nanoparticles both on the surface and in the bulk of the polymeric fibers, combined with the high surface area provided by the fibrous structure, result in a multifunctional material characterized by reversible UV-induced wettability and water permeability, improved thermal stability and antibacterial activity particularly promising for diverse applications such as filtration, wound management, photocatalysis, antibacterial and UV-shielding textiles.

We have designed an innovative protocol for the consolidation of waterlogged archaeological woods by using acetone mixtures of halloysite clay nanotubes and a chemically modified colophony (Rosin). Firstly, we have investigated the thermal properties of HNTs/Rosin nanocomposites, which have been prepared by means of the casting method from acetone. The HNTs content have been systematically changed in order to study the influence of the inorganic filler on the thermal stability and glass transition process of Rosin. We have observed that the thermal properties of the hybrids are affected by the specific HNTs/Rosin interactions. Then, acetone dispersions of HNTs/Rosin composites at variable filler content have been employed as consolidants for waterlogged archaeological woods. The quantitative analysis of the thermogravimetric curves have provided the amount of consolidants entrapped into the wood structure. These results have been successfully correlated to the consolidation efficiencies estimated from the analysis of the wood shrinkage volume upon drying. The attained knowledge represents the basic step to develop a green protocol for the long term protection of wooden art-works. © 2017, Springer Science+Business Media B.V.

The analysis of the recurrent characteristics of the local historic architecture is useful to develop large-scale energy analyses, regulations and financial strategies, but also to support technical guidelines for an energy improvement balanced with conservation. For this purpose, a multi-scale methodology ranging from envelope components to the urban dimension is necessary. In the research here exposed, this approach is investigated by focusing on the historic architecture of Palermo. For this heritage, the collection of thermal and hygrometric data for envelope components is combined with the examination of representative constructions, based on building stock categorization. Intended as a contribution to the overall energy analysis of the architectural heritage of Palermo, this case study shows that examining the recurrent characteristics of historic architecture in a local context may promote energy improvements compatible with the material and aesthetic conservation of historic buildings.

The current environmental and energetic crisis and the resulting regulations led to a new interest in using sustainable materials for building applications. Wood can be a material with high sustainable rates because it is recyclable, reusable and naturally renewable. Moreover, its excellent strength-to-weight ratios, thermal insulating and acoustical properties make it useful for different kinds of applications in buildings, ranging from structural beams and frames, insulating envelopes, windows, door frames, to wall and flooring materials and furniture. Although wood is commonly classified as a sustainable material, its real sustainability depends on different issues: appropriate forest management, manufacturing methods and site assembly, distance required for transportation and use of glues. Wood has also good seismic performances due to its lightweight and even if timber elements are not able to have a ductile behavior, using steel connection allows to build dissipative structure, as well platform frame and X-LAM panels systems. Insulation properties are related to low thermal conductivity values. Furthermore, wooden elements can be used to minimize sound transmission and they can be employed as sustainable materials as several Life Cycle Assessment studies demonstrate. This review paper aims to analyze the structural, thermal, acoustical and environmental properties of wooden materials for building applications; other properties such as fire resistance and durability were also taken into account. The work is completed by several tables and graphs with wood properties and by an updated and thorough reference list.

Plastics are perceived as modern and versatile materials, but their use is linked to numerous environmental issues as their production is based on finite raw materials (petroleum or natural gas). Additionally, their low biodegradability results in the accumulation of microplastics. As a result, there is extensive interest in the production of new, environmentally friendly, bio-based and biodegradable polymers. In this context, poly(ethylene vanillate) (PEV) has a great potential as a potentially bio-based alternative to poly(ethylene terephthalate), however, it has not yet been extensively studied. In the present work, the preparation of PEV is reported. The enthalpy and the entropy of fusion of the pure crystalline PEV have been estimated for the first time. Additionally, the equilibrium melting temperature has also been calculated. Furthermore, the isothermal and non-isothermal crystallization behavior are reported in detail, and new insights on the thermal stability and degradation mechanism of PEV are given.

Electrospinning of polymers has gained surging interest in the last decades due to its wide range of applications in different fields, such as sensors, electronic devices, separation systems, biomedical materials. Still there are only few reports on the use of these nanofibers as reinforcement in polymer composites. In this paper, solution electrospinning was employed to produce nanofibrous mats impregnating two epoxy resins to form “monolayer“systems, with the aim to study the influence of the nanofibers on both the curing behaviour and the morphology of the resin systems. Three polymers were chosen for producing electrospun mats, a polysulfone (PSF), a polyamide Nylon 6,6 (Ny66) and a polyacrilonitrile (PAN). The nanofibrous mats were employed to produce mat/epoxy monolayers by soaking the mat in two different epoxy resin systems, one in lab-synthesized-high performance, and the other commercial-low performance. The results show a different extent of swelling of the electronspun mats, as derived by morphological analysis. The observation of the fractured surfaces also indicates the formation of several fracture planes or phase separation phenomena, suggesting the possibility of dissipation of fracture energy by the epoxy/mat nanocomposites. Additionally, for all resin/mat arrangements, thermal analysis indicates no significant interference of the mat with the cure reactions of the resins and only slight changes of the glass transition temperatures.

Thermal conductivity measurements play a crucial role in most areas of the applied physical sciences, thereby constantly demanding for new non-invasive methods capable of providing high-resolution spatial mapping of absolute thermal conductivities on heterogeneous samples ranging from solid-state bulk materials to low-dimensionality structures. In this work, we lay the theoretical foundations and provide the experimental demonstration of a novel method for quantitative thermal conductivity mapping at tunable ∼10-μm resolution, by non-contact infrared photo-activated thermography. Starting from Fourier’s heat transfer law, we surmise a universal dependence of the thermal response of a laser-irradiated sample on its thermal conductivity, irrespectively of density and specific heat capacity. We demonstrate such a dependence over the three conductivity decades 0.1–100 W/mK by finite-element numerical simulations, and exploit it for proof-of-principle single-point thermal conductivity measurements on both thermally thick and thermally thin reference solid samples. We exemplify the feasibility of space-resolved measurements on eighteenth-century tin organ pipe fragments, where the product of the thermal conductivity times the sample thickness, imaged at 40-μm sub-diffraction resolution, is pointed out as a relevant parameter for the non-destructive characterization of the sample conservation state. By coupling temperature maps with the extraction of thermal properties at high spatial resolution, our approach significantly expands the capability of state-of-the-art infrared imaging technology in fully capturing the compositional heterogeneity and/or functional state of the imaged materials.

The aliphatic counterparts of the most used aromatic polyesters (PET, PPT, and PBT) have been synthesized by a two-stage polycondensation process, starting from dimethyl 1,4-cyclohexane dicarboxylate and different diols. The fully aliphatic polyesters are characterized by two cis/trans isomeric ratios (50 and 90 mol%) of the 1,4-cycloaliphatic rings. According to the cis/trans content, the properties of the materials notably change. Indeed, polymers rich in trans isomer are semicrystalline, whereas polymers with low trans content are fully amorphous, due to the presence of kinks along the chain. Trans isomer is characterized by higher rigidity than the cis one and the corresponding polymers have high glass transition temperatures. Moreover, the length of the methylene sequences in the diol has a notable influence on the final thermal and mechanical properties. Therefore, tunable properties can be easily obtained. This characteristic, in association with good mechanical performances, potential sustainability of the monomers and biodegradability, makes these aliphatic polyesters an interesting class of polyesters for some specific applications.

The present paper describes the synthesis of novel bio-based poly(butylene 1,4-cyclohexane dicarboxylate)-containing random copolymers for sustainable and flexible packaging applications. On one side, the linear butylene moiety has been substituted by glycol subunits with alkyl pendant groups of different length. On the other side, copolymers with different cis/trans isomer ratio of cyclohexane rings have been synthesized. The prepared samples were subjected to molecular, thermal, diffractometric, and mechanical characterization. The barrier performances to O2, CO2, and N2 gases were also evaluated. The presence of side alkyl groups did not alter the thermal stability, whereas it significantly influences the formation of ordered phases that deeply affect the functional properties, mainly in terms of mechanical response and barrier performance. In particular, the final materials present higher flexibility and significantly improved barrier properties with respect to the homopolymer and most polymers widely employed for flexible packaging. The improvement due to copolymerization was more pronounced in the case of higher co-unit-containing copolymers and for the samples with cyclohexane rings in the trans conformation.

Both academia and industry are currently devoting many efforts to develop high gas barrier bioplastics as substitutes of traditional fossil-based polymers. In this view, this contribution presents a new biobased aromatic polyester, i.e., poly(propylene 2,5-thiophenedicarboxylate) (PPTF), which has been compared with the furan-based counterpart (PPF). Both biopolyesters have been characterized from the molecular, thermo-mechanical and structural points of view. Gas permeability behavior has been evaluated with respect to 100% oxygen, carbon dioxide and nitrogen at 23 &deg, C. In case of CO2 gas test, gas transmission rate has been also measured at different temperatures. The permeability behavior at different relative humidity has been investigated for both biopolyesters, the thiophen-containing sample demonstrating to be better than the furan-containing counterpart. PPF&rsquo, s permeability behavior became worse than PPTF&rsquo, s with increasing RH, due to the more polar nature of the furan ring. Both biopolyesters under study are characterized by superior gas barrier performances with respect to PEF and PET. With the simple synthetic strategy adopted, the exceptional barrier properties render these new biobased polyesters interesting alternatives in the world of green and sustainable packaging materials. The different polarity and stability of heterocyclic rings was revealed to be an efficient tool to tailor the ability of crystallization, which in turn affects mechanical and barrier performances.

Polycarbonate panels could be considered as a suitable and cheap solution for walls, roofs, and sheds in non-residential buildings and, at the same time, granular silica aerogel is one of the most promising nano-materials for energy saving in buildings. In the paper, three types of advanced multiwall PC panels (thickness 16, 25, and 40 mm) with translucent granular aerogel were investigated by experimental (thermal and optical) and numerical characterization. By comparing thermal performance of air and aerogel-filled PC systems, it can be noticed that the impact of the aerogel is remarkable: the reduction in U-value is 46%-68%, depending on the aerogel layer thickness. U-value is 1.4 W/m2K for the 16 mm thickness sample and it is 0.6 W/m2K when the thickness increases up to 40 mm. The systems keep their performance in horizontal position, when they are used as roofs. Light transmittance is 0.61 and 0.42 for 16 mm and 40 mm respectively and the reduction with respect to air-filled panels is acceptable (15%) for 16 mm and significant (40%) for 40 mm thickness. The aerogel has also a remarkable impact on the reflectance spectrum, especially between 400 and 1400 nm. The solar factor is 0.58 for 25 mm thickness, quite similar to the low-e glazing one. Finally, energy simulations for a case study showed that aerogel-filled PC systems outperform conventional double glazing systems both for heating and cooling energy demands. However, when compared to low-e glazings, the benefits of the translucent material (also considering the highest thickness) in the interspace are lower for heating and negligible for cooling energy demands. The aerogel-filled polycarbonate systems could be a valid solution for non-residential buildings, enhancing the thermal performance and the light control of the building envelope, especially when they are used as roofs. © 2018 Elsevier B.V.

An analytical overview of experimental results about the heat transfer capabilities of nanofluids is presented, using widely scattered available information from diverse literature sources. It is shown that, despite the large number of publications available about this issue, only few studies provide quantitative estimates on a complete set of experimental conditions so far and many studies are not coherent. Bearing in mind this problem, in this study a selection of the most valuable papers has been done, taking into account different points of view and hypotheses. Even if this work cannot be considered exhaustive of the complete literature in the field of nanofluids, it can be taken into account as a quick reference guide to have an overview of the different heat transfer phenomena in nanofluids and how the most important parameters (size, shape, concentration, materials etc.) influence the expected thermal performance of nanofluids. (C) 2014 Elsevier Ltd. All rights reserved.

In the last decade, there has been an increased interest from the food packaging industry toward the development and application of bioplastics, to contribute to the sustainable economy and to reduce the huge environmental problem afflicting the planet. In the present work, we focus on a new furan-based polyester, poly(neopentyl glycol 2,5-furanoate) (PNF) to be used for sustainable food packaging applications. The aromatic polyester was successfully synthesized with high molecular weight, through a solvent-free process, starting directly from 2,5-furandicarboxylic acid. PNF was revealed to be a material with good thermal stability, characterized by a higher Tg and Tm and a lower RAF fraction compared to poly(propylene 2,5-furanoate) (PPF), ascribable to the two methyl side groups present in PNF glycol-sub-unit. PNF’s mechanical characteristics, i.e., very high elastic modulus and brittle fracture, were found to be similar to those of PPF and PEF. Barrier properties to different gases, temperatures and relative humidity were evaluated. From the results obtained, PNF was showed to be a material with very smart barrier performances, significantly superior with respect to PEF’s ones. Lastly, PNF’s permeability behavior did not appreciably change after contact with food simulants, whereas it got worse with increasing RH, due to the polar nature of furan ring.

Studies on the adsorption of biopolymers onto halloysite nanotubes (HNTs) in water were conducted. Three polymers with different charges-anionic (pectin), neutral (hydroxypropyl cellulose), and cationic (chitosan)-were chosen. The thermodynamic parameters for the adsorption of polymers onto the HNT surface were determined by isothermal titration calorimetry (ITC). The experimental data were interpreted based on a Langmuir adsorption model. The standard variations in free energy, enthalpy, and entropy of the process were obtained and discussed. Turbidimetry was used to evaluate the stability of functionalized nanoparticles in water. The ζ-potential clarified the surface charge properties of functionalized nanotubes upon polymer adsorption. The interaction of modified nanotubes with polymers led to the formation of a colloidal system with tunable stability and surface properties, which offers different perspectives on new applications of these dispersions, such as carriers for substances to be released in response to external stimuli. © 2017 American Chemical Society.

In the last decade, there has been an increased interest from the food packaging industry toward the development and application of biodegradable and biobased plastics, to contribute to the sustainable economy and to reduce the huge environmental problem afflicting the planet. In this framework, the present paper describes the synthesis of novel PBS (poly(butylene succinate))-based random copolymers with different composition containing glycol sub-units characterized by alkyl pendant groups of different length. The prepared samples were subjected to molecular, thermal, diffractometric and mechanical characterization. The barrier performances to O2, CO2 and N2 gases were also evaluated, envisioning for these new materials an application in food packaging. The presence of the side alkyl groups did not alter the thermal stability, whereas it significantly reduced the sample crystallinity degree, making these materials more flexible. The barrier properties were found to be worse than PBS; however, some of them were comparable to, or even better than, those of Low Density Polyethylene (LDPE), widely employed for flexible food packaging. The entity of variations in the final properties due to copolymerization were more modest in the case of the co-unit with short side methyl groups, which, when included in the PBS crystal lattice, causes a more modest decrement of crystallinity degree.

This study investigates the effects of commercial nanoparticles on thermal and mechanical performance of rigid polyurethane foams. Two different types of nanoparticles are considered as fillers, spherical titania and rod-shaped halloysite clay nanotubes. The aim of this study was to produce rigid polyurethane foams modified with titania nanocrystals and nanohalloysite in order to obtain polyurethanes with improved properties. The laboratory scale-up will be suitable for the production in many branches of industry, such as construction and automotive production. In particular, these foams, added with commercial nanoparticles, characterized by better thermal and mechanical properties, are mainly used in construction for thermal insulation of buildings. The fillers were dispersed in the components, bringing rates up to 10%. In these investigations, the improvement of the thermal properties occurs by adding nanoparticles in the range 4–8% of titania and halloysite. The mechanical properties instead have been observed an improvement starting from 6% of nanoparticles addition. All data are in agreement with scanning electron microscope observations that shown a decrease in the average cell size and an increase in the cell density by adding nanoparticles in foams.

This research investigates an external wall system made with hemp-based composites for a possible application in the civil engineering. In particular, the wall system is realized with panels of two different densities. First of all, physical and mechanical properties of the panels are studied, together with fire reaction and resistance behavior. Then, the external wall system is investigated by means of impact energy of the external surface, thermal and acoustic properties. The composite materials exhibit an outstanding and not common combination of properties. This research shows first preliminary results aimed at implementing sustainable processes in the constructions industry.

ZnO is receiving a considerable attention for the development of novel cost-effective one-dimensional nanostructures with outstanding functional properties for applications in electronics and energy. We propose a fully-coupled thermo-mechanical-electric scheme to study the current-voltage characteristic of piezoelectric ZnO NWs under a purely vertical compressive/tensile strain. Our results confirm that the thermal transport processes deeply affect the behavior of devices for piezoelectric-piezotronic applications and provides remarkable insights into the underlying physics. © 2015 IEEE.

none 8 no Nylon 6,6 electrospun nanofibrous membranes interleaved in Carbon Fibre Reinforced Plastic (CFRP) laminates have been proposed as a means to provide a higher threshold value to delamination on structural sites where composites are more prone to develop such failure. A model, highly crosslinked thus inherently brittle, epoxy matrix was selected for its high Young’s modulus and glass transition temperature exceeding 250 °C. The influence of the Nylon 6,6 nanofibres on the curing behaviour of the matrix and on the thermal and dynamic mechanical properties of the cured resin was investigated. These properties were related to the features of the epoxy resin and of the resin impregnated nanofibrous mat. Finally, the delamination behaviour of two composite laminates interleaved with different thicknesses of Nylon interleaf was studied through Mode I delamination tests. The initial Mode I fracture toughness was increased up to about 50% by the presence of a thin mat interleaf. none S ALESSI; M Di FILIPPO; C DISPENZA; ML FOCARETE; C GUALANDI; R PALAZZETTI; G PITARRESI; A ZUCCHELLI S ALESSI; M Di FILIPPO; C DISPENZA; ML FOCARETE; C GUALANDI; R PALAZZETTI; G PITARRESI; A ZUCCHELLI

The addition of fibres to a brittle matrix is a well-known method to improve the flexural strength. However, the success of the reinforcements is dependent on the interaction between the fibre and the matrix. This paper presents the mechanical and microstructural properties of PVA and basalt fibre reinforced geopolymers. Moreover low density and thermal resistant materials used as insulating panels are known be susceptible to damage due to their poor flexural strength. As such the thermal and fire resistance properties of foamed geopolymers containing fibre reinforcement were also investigated. The results highlight that the presence of PVA fibres greatly increased the flexural strength and the toughness of the geopolymer composite, while the presence of basalt fibres improved the flexural behaviour of the composite after high temperature exposure.