Search results for " tecnologia."
showing 10 items of 1339 documents
Participación ciudadana en los perfiles de Facebook de los partidos españoles. Análisis de comentarios en la campaña electoral de 2015
2017
El uso de redes sociales por parte de los partidos políticos para la difusión de sus mensajes posibilita la participación ciudadana y la creación de debate entre los usuarios. El presente estudio analiza esta participación a través de los comentarios que escriben los ciudadanos en las páginas de Facebook de los principales partidos políticos españoles durante la campaña de las elecciones generales de 2015. El objetivo es establecer las características de la participación ciudadana en un contexto político y comprobar si existen diferencias entre los comentarios publicados en los distintos partidos. El estudio utiliza una metodología cuantitativa articulada en dos fases. En primer lugar, se a…
PLLA-fibrin scaffolds for Vascular Tissue Engineering
2013
Thermal and rheological characterisation of a thermoset matrix for filament winding modelling
2004
Rheo-kinetic behaviour of an epoxy resin, coupled with an aliphatic polyamines hardener, used in fibre reinforced plastics, was analysed comparing experimental data to theoretical models. Then the modelling of technological filament winding process for thermoset matrix composites, developed through a numerical code realized with MATLAB, is reported. The model includes winding and curing phase decoupling the manufacturing process into sub-models. Four sub-models are used: fibre motion, thermal, kinetic and rheological model. Considerable differences are obtained in process condition, using several thermal treatments. The numerical modelling helps to detect the process conditions to optimise…
PLA based biocomposites reinforced with Posidonia oceanica leaves
2018
Abstract Biocomposites can valorize some natural products related to natural processes or crop and waste industries. In this work, leaves of Posidonia oceanica (PO), dominant sea grass in the Mediterranean Sea, were used to prepare PLA based biocomposites. Materials were prepared by melt mixing PLA with PO as filler. The morphology as well as the mechanical and thermal properties of PLA/PO composites were evaluated and related with the influence of the content and size of PO. Moreover, the experimental elastic moduli of the biocomposites was modelled employing the Halpin–Tsai (HT) model. Furthermore, in order to take into consideration the high porosity of PO leaves, the HT parameters relat…
Use of Biochar as Filler for Biocomposite Blown Films: Structure-Processing-Properties Relationships
2021
In this work, biocomposite blown films based on poly(butylene adipate-co-terephthalate) (PBAT) as biopolymeric matrix and biochar (BC) as filler were successfully fabricated. The materials were subjected to a film-blowing process after being compounded in a twin-screw extruder. The preliminary investigations conducted on melt-mixed PBAT/BC composites allowed PBAT/BC 5% and PBAT/BC 10% to be identified as the most appropriate formulations to be processed via film blowing. The blown films exhibited mechanical performances adequate for possible application as film for packaging, agricultural, and compost bags. The addition of BC led to an improvement of the elastic modulus, still maintaining h…
In situ monitoring of moisture uptake of flax fiber reinforced composites under humid/dry conditions
2021
The use of green materials such as natural fiber-reinforced composites represents an increasingly stringent prerogative in the future planning of industrial and non-industrial production. The optimization of these materials is the main aim of the current research, focused on the evaluation of the behavior of flax fiber reinforced composites exposed to isothermal adsorption and desorption cycles, at varying the partial pressure of water vapor (P/P0). For this purpose, the moisture uptake and the morphology changes of the composite material and their constituents were in situ monitored through a measurement protocol, by using a dynamic vapor sorption (DVS) analysis, coupled with an environmen…
Effectiveness of sodium acetate treatment on the mechanical properties and morphology of natural fiber-reinforced composites
2021
This paper aims to investigate the ability of an eco-friendly and cheap treatment based on sodium acetate solutions to improve the mechanical properties of flax fiber-reinforced composites. Flax fibers were treated for 5 days (i.e., 120 h) at 25 °C with mildly alkaline solutions at 5%, 10% and 20% weight content of the sodium salt. Quasi-static tensile and flexural tests, Charpy impact tests and dynamical mechanical thermal (DMTA) tests were carried out to evaluate the mechanical properties of the resulting composites. Fourier transform infrared analysis (FTIR) was used to evaluate the chemical modification on the fibers surface due to the proposed treatment, whereas scanning electron micro…
Improving the mechanical properties of unidirectional flax fabrics reinforced epoxy composites by sodium bicarbonate treatment
2017
Despite their beneficial effects on the adhesion between natural fibers and polymeric matrices, chemical pretreatments have become less attractive since they are expensive and harmful to environment. The present paper deals with the effect of an eco-friendly and cost effective treatment, based on the use of a sodium bicarbonate solution, on the mechanical performances of flax reinforced epoxy composites. Materials and methods: A commercial epoxy resin and unidirectional flax fabrics (190 g/m2 areal density) were used as matrix and reinforcement, respectively. The fabrics were soaked in 5 and 10 wt% solutions of sodium bicarbonate for 5 days at 25°C, then dried at 105°C for 1 day. By using u…
PALERMO SICILIAN GARDEN
2019
Palermo, città-giardino fin dalle sue origini, ha fatto del verde una delle sue espressioni più manifeste. La città conserva come in un scrigno le testimonianze più significative della storia del verde che occupa un ruolo determinante dal punto di vista ambientale, storico e paesaggistico. Agli splendidi parchi della Conca d'Oro che un tempo abbracciavano la città, fanno eco i meravigliosi giardini privati nascosti all’interno di palazzi nobiliari, chiese e monasteri e i parchi e le ville pubbliche, alcuni dei quali trasformati oggi in spazi di verde attrezzato e orti urbani. Il contributo espone gli esiti di uno studio condotto presso il Dipartimento di Architettura dell'Università di Pale…
Training for professionals engaged on the construction front: the SITdA commitment and the Agreement with ANCE and AFM Edilizia / La formazione dei p…
2012
L’articolo si sofferma sulle premesse dell’Accordo siglato a Roma nel maggio 2012 tra Società Italiana di Tecnologia dell’Architettura, l’Associazione Nazionale Costruttori Edili e l’Associazione Formazione Manageriale Edilizia, con l’intento di promuovere la formazione di figure professionali attrezzate ad affrontare gli scenari sempre più complessi del mondo delle costruzioni. Nonostante manifesti pesanti conseguenze della crisi generale, il settore edilizio mantiene un ruolo strategico nell’economia nazionale e impone obiettivi di qualità ed efficacia in tutte le fasi degli interventi, rendendo indispensabile un’ottica sistemica e processuale. A ciò corrisponde un rinnovato ruolo della f…