Search results for "Materiali"
showing 10 items of 876 documents
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…
Jean-Paul Sartre: cultura egemonica e cultura subalterna
2017
Scorrendo l’indice delle opere letterarie e teatrali di Jean-Paul Sartre, si po- trebbe ricavare l’impressione di trovarci dinanzi ad un autore che ha realizzato una vasta ed articolata produzione sezionabile in più parti. Di conseguenza si potrebbe desumere che ciascuna opera risulti slegata dalle altre, costituenti il complesso e ricco mosaico dell’uomo di cultura francese. In effetti, il Sartre scrittore e saggista o autore di opere teatrali non può essere disgiunto dal Sartre fi losofo.
Materialism and the Bright and Dark Sides of the Financial Dream in Spain: The Positive Role of Money Attitudes-The Matthew Effect
2012
Research suggests that materialism leads to the dark side of the financial dream. In this study, we treat love of money as a mediator and test a theoretical model's direct path (Materialism to Financial Satisfaction) and indirect path (Materialism to Love of Money to Financial Satisfaction) simultaneously using the whole sample and across several demographic variables based on 1,011 citizens in Spain. Results for the whole sample showed that the positive indirect effect suppressed the negative direct effect creating an overall small positive effect. Furthermore, we found a significant negative direct path for rural dwellers, the 30–44-year-old age group, and married people, but a positive i…
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…
Le strutture difensive delle colonie greche di Sicilia. Storia, tipologia, materiali
2010
Il presente Volume si propone di approfondire la conoscenza storica, tipologica e materica delle strutture difensive presenti nei maggiori siti archeologici siciliani di fondazione greca, premessa indispensabile per un qualsiasi tipo di intervento di recupero e fruizione. Il Volume affronta, innanzitutto, il tema della colonizzazione greca in Sicilia, in quanto la nascita delle fortificazioni è strettaente correlata alla necessità di difendersi dalle popolazioni indigene, e indaga sulle relazioni esistenti fra fortificazioni e tipologie insediative, soffermandosi, in seguito ad analizzare i vari subsistemi (fondazioni, muri, coronamenti, smaltimento delle acque) e componenti (porte e torri)…
Visco-elastic behavior through fractional calculus: an easier method for best fitting experimental results
2011
In capturing visco-elastic behavior, experimental tests play a fundamental rule, since they allow to build up theoretical constitutive laws very useful for simulating their own behavior. The main challenge is representing the visco-elastic materials through simple models, in order to spread their use. However, the wide used models for capturing both relaxation and creep tests are combinations of simple models as Maxwell and/or Kelvin, that depend on several parameters for fitting both creep and relaxation tests. This paper, following Nutting and Gemant idea of fitting experimental data through a power law function, aims at stressing the validity of fractional model. In fact, as soon as rela…
Mechanical properties of basalt fiber reinforced composites manufactured with different vacuum assisted impregnation techniques
2016
Abstract This work describes an experimental mechanical characterisation campaign on composites made out of a quasi-unidirectional basalt fabric. In order to evaluate the ability of commercial basalt fabrics and their composites to meet the potentials of basalt fibers, the work has used raw materials from commercial catalogs with no further modification. Two common manufacturing techniques for medium performance composites have been adopted: vacuum assisted resin infusion, and hand-impregnated vacuum bagging. Two panels, one for each technique, have been fabricated, able to provide a sufficient number of samples for a comprehensive stiffness and strength characterization through Tensile, Fl…