1,721,051 research outputs found
On the essential work of fracture of neat and rubber-toughened polyamide-66
No full textEssential work of fracture (EWF) tests have been conducted on neat and rubber toughened polyamide-66 in order to measure the essential specific work of fracture (w e) and the non-essential specific work of fracture (βw p) parameters. Further, the w e value has been partitioned into two terms, one related to the specific energy contribution for yielding up to the onset of fracture (w e,init), and another one representing the subsequent crack propagation process (w e,prop), respectively. EWF tests performed on neat polyamide-66 specimens conditioned up to various equilibrium moisture contents clearly indicate that w e markedly increases as the material moisture content rises, and that this trend is mainly associated with the increase of its crack propagation component (w e,prop), the initiation related term (w e,init) being practically independent of the humidity level. The inclusion of various amounts (7, 16, and 25 wt%) of rubber particles (a random ethylene-acrylic ester-maleic anhydride terpolymer) into the polyamide-66 matrix induces a large increase of the w e parameter. It is interesting to observe that the w e,init and w e,prop terms display different trends with the rubber content. Most of the toughening effect of the rubber particles can be attributed to a large increase of the propagation-related term, the fracture initiation term decreasing with the rubber content. Finally, the loading rate effects on the fracture behaviour have been investigated for polyamide-66 toughened with 25 wt% rubber. An increase of the loading rate causes an increase of the crack-initiation related term w e,init, while the crack-propagation related parameter w e,prop decreases. As a consequence, the specific term w e shows a non-monotonic trend with the loading rate
Determination of the fracture toughness of thermoformed polypropylene cups by the essential work method
No full textEnergy storage and recovery of post-yield deformed semicrystalline poly(butylene terephthalate): deformation temperature and rate effects
No full textDeformation temperature and strain rate effects on non elastic strain recovery of semicrystalline poly(butylene terephthalate)
No full textElectrically conductive epoxy nanocomposites containing carbonaceous fillers and in-situ generated silver nanoparticles
Full text linkAn epoxy resin was nanomodified with in-situ generated silver nanoparticles (Ag) and with various amounts of carbon black (CB) and carbon nanofibers (NF), in order to increase the electrical conductivity of the matrix. Differential scanning calorimetry tests revealed how the addition of both CB and NF led to a slight decrease of the glass transition temperature of the material, while electron microscopy evidenced how the dimension of CB aggregates increased with the filler content. Both flexural modulus and stress at yield were decreased by CB addition, and the introduction of Ag nanoparticles promoted an interesting improvement of the flexural resistance. CB resulted to be more effective than NF in decreasing the electrical resistance of the materials down to 103 Ω•cm. Therefore, a rapid heating of the CB-filled samples upon voltage application was observed, while Ag nanoparticles allowed a stabilization of the temperature for elevated voltage application times
Intraply and interply hybrid composites based on E-glass and poly(vinyl alcohol) woven fabrics: tensile and impact properties
No full textE-glass and poly(vinyl alcohol) (PVA) fibres were used to produce both homogeneous and hybrid composites with an orthophthalic unsatured polyester resin. Results are presented regarding the tensile and impact behaviour of both intraply and interply hybrid composites, with particular regard to the effects of the plies stacking sequence and the loading direction. With a proper choice of composition and stacking sequence, E-glass/PVA hybrid composites were proved to achieve a property profile superior to those of homogeneous E-glass laminates in terms of specific properties. In particular, hybridization with PVA fibres resulted in improving the specific impact energy of E-glass laminates. Resistance to impact crack propagation was higher for intraply with respect to interply hybrid composites, as evidenced by their ductility index values
Il Dante di Bruno Nardi tra filosofia, poesia e profetismo
No full textL’articolo ricostruisce l’idea e l’immagine di Dante che emerge dagli studi di Bruno Nardi, che coprono il lasso di tempo che va dalla tesi discussa nel 1911 fino alla morte nel 1968. Anziché investigare la sua analisi di singoli problemi dottrinali, gli autori si concentrano sulle premesse ideologiche dell’approccio di Nardi a Dante, profondamente radicato in una concezione della filosofia come visione unitaria dell’esperienza umana, di cui la dimensione teologica e religiosa fanno pienamente parte. Particolare attenzione è dedicata al contesto filosofico in cui lo studioso operò e maturò i suoi lavori danteschi. Il Dante di Nardi emerge come poeta la cui opera risponde a domande di carattere esistenziale ed è mossa da una profonda istanza profetica
Effect of supercritical carbon dioxide pasteurization on natural microbiota, texture and microstructure of fresh-cut coconut
No full textTerminologia linguistica, studio dell’ebraico ed esegesi biblica nelle «Note» attribuite a Ruggero Bacone (BML, Plut. 25 sin. 4)
No full textIn questo articolo intendo analizzare un testo particolare, per molti versi eccezionale, contenuto nel Pluteo 25 sin. 4 della Biblioteca Medicea Laurenziana, manoscritto che appartiene alla biblioteca di Santa Croce, verosimilmente al suo nucleo antico. Si tratta di un insieme di Note esegetiche e di argomento linguistico sulla Bibbia ebraica, costituito da più parti, tra cui uno scambio epistolare, benché sia compilato come un’unità da Guglielmo de la Mare
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