Search results for "Composite"
showing 10 items of 4584 documents
Industrial Hemp Transformation for Composite Applications: Influence of Processing Parameters on the Fibre Properties
2017
The main objective of this collaborative work is to characterize the influence of the processing stages of industrial hemp on the fibre properties. Transformation processes well suited for composite reinforcing textiles are considered. The work focuses on the different stages along the transformation chain of hemp, from the straw retting to the preform manufacturing. The main highlight is the predominant influence of retting on the tensile properties of individual fibres after their mechanical extraction from the stalks. Regarding the secondary processing, different technologies such as spinning, and use of natural binder systems are also proposed to produce yarns and woven fabrics. The eff…
Influence of some relevant process parameters on the dimensional accuracy in incremental forming: a numerical and experimental investigation
2004
Abstract As known, incremental forming is a flexible and innovative sheet metal forming process which allows complex shape shells forming without the need for any die. For these reasons, incremental forming is nowadays suggested for rapid prototyping and customised products. The present paper is focused on material formability in incremental forming and, in particular, on the evaluation and compensation of elastic springback. The latter significantly modifies the imposed shape. For this purpose, a deeper assessment of the process was developed following three different approaches. First of all, a wide experimental investigation on the influence of some relevant process parameters was develo…
Rheological and Flocculation Analysis of Microfibrillated Cellulose Suspension Using Optical Coherence Tomography
2018
A sub-micron resolution optical coherence tomography device was used together with a pipe rheometer to analyze the rheology and flocculation dynamics of a 0.5% microfibrillated cellulose (MFC) suspension. The bulk behavior of the MFC suspension showed typical shear thinning (power-law) behavior. This was reflected in a monotonously decreasing floc size when the shear stress exceeded the yield stress of the suspension. The quantitative viscous behavior of the MFC suspension changed abruptly at the wall shear stress of 10 Pa, which was reflected in a simultaneous abrupt drop of the floc size. The flocs were strongly elongated with low shear stresses. With the highest shear stresses, the flocs…
Random Lasing of Rhodamine 6G Solution Containing TiO2:Silica Core:Shell Nanoparticles
2012
High efficiency and low rate of photodegradation was obtained in a random laser suspending TiO2@Silica nanoparticles in ethanol solution of Rhodamine 6G. The TiO2 nanoparticles were coated with a silica shell prepared via Stober method.
X-ray powder diffraction study of monoclinic V4+-ZrO2 solid solutions obtained from gels
2003
Abstract Rietveld refinement of six monoclinic V x Zr 1− x O 2 solid solutions, with x =0, 0.01, 0.02, 0.05, 0.075 and 0.1, prepared by heating dried gel precursors at 1300°C in air atmosphere, has been characterized using X-ray powder diffractometer data. The present results confirm that crystal structure of these solid solutions contain V 4+ (Zr 4+ ) cations surrounded by seven oxygens, four at a distance between 2.13 and 2.28 A (referred as to O(2) in the tetrahedrally coordinated oxygens) and other three at a distance between 2.03 and 2.20 A (denoted as O(1) in the triangularly coordinated oxygens). The trends in the lattice parameter variation of V x Zr 1− x O 2 solid solutions specime…
Cerium effect on the phase structure, phase stability and redox properties of Ce-doped strontium ferrates
2006
Nanostructured perovskite-type Sr1−aCeaFeO3−x, (0⩽a<0.15) powders have been prepared by citrate–nitrate smoldering auto-combustion. Their phase structure and stability, surface and morphological properties, reduction behavior and interaction with oxygen have been investigated by X-ray Powder Diffraction combined with Rietveld Analysis, 57Fe Mossbauer and X-ray Photoelectron Spectroscopies, N2-adsorption method, Temperature Programmed Reduction and Oxidation experiments. Our results reveal that citrate–nitrate auto-combustion method is effective in obtaining single phase Sr1−aCeaFeO3−x. The Sr1−aCeaFeO3−x structure is cubic only for a⩾0.06, while for a<0.06 remains tetragonal. Moreover, for …
Structural and morphological properties of Co-La catalysts supported on alumina/lanthana for hydrocarbons oxidation
2004
Abstract Two Al 2 O 3 (24 wt%)–La 2 O 3 (76 wt%) supported Co–La oxides with Co loading 4 wt% and different La content (1 and 9 wt%) were prepared by co-impregnation of the support, the aluminum–lanthanum oxide, with cobalt and lanthanum nitrates in aqueous solution and successive calcination at 800 °C for 4 h. The alumina–lanthana was synthesized by the sol–gel method. The samples were characterized by X-ray diffraction (XRD) and Rietveld refinement in order to identify the crystalline phases and their relative weight. H 2 -TPR (Temperature Programmed Reduction) experiments were recorded with the aim to identify the different Co phases present. Co 3 O 4 and LaCoO 3 were formed for La loadi…
Study and evaluation of nano-structured cellulose fibers as additive for restoration of historical mortars and plasters
2017
Abstract UPM bio-fibrils are nano-structured cellulose fibers (nano-fibrils) produced by UPM Kymmene-Corporation, a Finnish company. This paper reports a preliminary study about nano-fibrils to determine their possible use for restoration of historical mortars and plasters. The aim of this study is to investigate the behavior of some mixtures added with nano-fibrils in their properties for conservative purposes. These mixtures reproduce the composition of historical mortars and plasters, made of natural hydraulic lime (NHL 3.5) and river sand. After 28 days of hardening, the properties of specimens with nano-fibrils were compared with untreated one to understand how nano-fibrils interact wi…
Integrating Circularity in the Sustainability Assessment of Asphalt Mixtures
2020
Rising concerns about the impacts that the road engineering industry is imposing to the environment have redirected national road authorities to firmly re-consider the sustainability implications of their operations. Lately, though, sustainability has established a forceful correlation with the Circular Economy and its principles. The road engineering industry, therefore, is moving towards more circular approaches. However, this is occurring without the assessment of the potential impacts of such a transition. For this reason, in this study, a composite indicator, namely, Environmental Sustainability and Circularity indicator (ESCi), for investigating the potential effects that increased ci…
Intraorifice sealing ability of different materials in endodontically treated teeth.
2010
Objectives To evaluate Cavit TM G, ProRoot TM MTA and Tetric® EvoFlow as intraorifice barriers to prevent coronal microleakage in root canal treatment. Study design Forty-two human single rooted teeth were divided randomly in three experimental groups of 10 specimens each and two control groups. The experimental groups were prepared with hand instrumentation and cold lateral condensed technique of the gutta-percha. Four millimetres of coronal gutta-percha were removed and replaced by one of the following filling materials: Cavit TM G, Tetric® EvoFlow or ProRoot TM MTA. In the experimental groups, leakage was measured by the concentration of leaked glucose in the apical reservoir at 1, 7, 30…