Search results for "mechanical performance"
showing 10 items of 14 documents
Halloysite Nanotubes Loaded with Calcium Hydroxide: Alkaline Fillers for the Deacidification of Waterlogged Archeological Woods
2018
A novel green protocol for the deacidifying consolidation of waterlogged archaeological woods through aqueous dispersions of polyethylene glycol (PEG) 1500 and halloysite nanotubes containing calcium hydroxide has been designed. First, we prepared functionalized halloysite nanotubes filled with Ca(OH)2 in their lumen. The controlled and sustained release of Ca(OH)2 from the halloysite lumen extended its neutralization action over time, allowing the development of a long-term deacidification of the wood samples. A preliminary thermomechanical characterization of clay/polymer nanocomposites allows us to determine the experimental conditions to maximize the consolidation efficiency of the wood…
The durability of basalt fibres reinforced polymer (BFRP) panels for cladding
2015
The study focuses on two basalt composite laminate panels for cladding, produced by means of vacuum bagging technique. In particular, unidirectional and random basalt fabrics, with different areal weights, using epoxy resin as matrix, were used. According to the ISO 15686 methodology for the evaluation of durability, samples were subjected to cycles of artificial aging in climatic chamber and outdoor exposure, carrying out mechanical (i.e. quasi-static and dynamic) and calorimetric tests. The results show the effectiveness over time of produced basalt composite laminates and the initial increase of the mechanical performances after the first steps of accelerated aging.
Strategies for waste recycling : the mechanical performance of concrete based on limestone and plastic waste
2022
Recycling is among the best management strategies to avoid dispersion of several types of wastes in the environment. Research in recycling strategies is gaining increased importance in view of Circular Economy principles. The exploitation of waste, or byproducts, as alternative aggregate in concrete, results in a reduction in the exploitation of scarce natural resources. On the other hand, a productive use of waste leads to a reduction in the landfilling of waste material through the transformation of waste into a resource. In this frame of reference, the paper discusses how to use concrete as a container of waste focusing on the waste produced in limestone quarries and taking the challenge…
Influence of material and diameter of pre-fabricated posts on maxillary central incisors restored with crown.
2009
Summary Numerous research works have studied the effect of post-design parameters on the mechanical behaviour of restored teeth without reaching any clear conclusions. Previous works by the authors ascertained the effect of material and post-dimensions for non-crowned restored teeth. The aim of this work was to study the effect of post-material and diameter for crowned teeth. First, an experimental fracture strength test was performed on eighteen extracted human maxillary central incisors. Teeth were decoronated, treated endodontically and restored (nine with glass fibre posts and nine with stainless steel posts). Several post-diameters were used. The final crown restoration was carried ou…
The role of crystalline, mobile amorphous and rigid amorphous fractions in the performance of recycled poly (ethylene terephthalate) (PET)
2012
[EN] The action of thermo-mechanical degradation induced by mechanical recycling of poly(ethylene terephthalate) was simulated by successive injection moulding cycles. Degradation reactions provoked chain scissions and a reduction in molar mass mainly driven by the reduction of diethyleneglycol to ethylene glycol units in the flexible domain of the PET backbone, and the formation of -OH terminated species with shorter chain length. The consequent microstructural changes were quantified taking into account a three-fraction model involving crystalline, mobile amorphous (MAF) and rigid amorphous fractions (RAF). A remarkable increase of RAF, to a detriment of MAF was observed, while the percen…
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…
Filling of Mater-Bi with Nanoclays to Enhance the Biofilm Rigidity
2018
We investigated the efficacy of several nanoclays (halloysite, sepiolite and laponite) as nanofillers for Mater-Bi, which is a commercial bioplastic extensively used within food packaging applications. The preparation of Mater-Bi/nanoclay nanocomposite films was easily achieved by means of the solvent casting method from dichloroethane. The prepared bio-nanocomposites were characterized by dynamic mechanical analysis (DMA) in order to explore the effect of the addition of the nanoclays on the mechanical behavior of the Mater-Bi-based films. Tensile tests found that filling Mater-Bi with halloysite induced the most significant improvement of the mechanical performances under traction force, …
Performance of Thin-Film Lithium Energy Cells under Uniaxial Pressure
2008
The objective of this study was two-fold. The first objective was to determine if the all-solid-state thin-film lithium energy cells could withstand the minimal 550 kPa uniaxial pressure required for composite manufacturing, which both specimens successfully did. The second objective was to determine the upper boundary uniaxial pressure limit of operation for the all-solid-state thin-film lithium energy cells. The two all-solid- state thin-film lithium energy cells tested in the present study under uniaxial pressure performed well even when subjected to uniaxial pressures up to about 2.0 MPa. However, pressures higher than this value led to their degradation. The observed degradation was du…
Ocean acidification bends the mermaid's wineglass
2015
Ocean acidification lowers the saturation state of calcium carbonate, decreasing net calcification and compromising the skeletons of organisms such as corals, molluscs and algae. These calcified structures can protect organisms from predation and improve access to light, nutrients and dispersive currents. While some species (such as urchins, corals and mussels) survive with decreased calcification, they can suffer from inferior mechanical performance. Here, we used cantilever beam theory to test the hypothesis that decreased calcification would impair the mechanical performance of the green alga Acetabularia acetabulum along a CO 2 gradient created by volcanic seeps off Vulcano, Italy. Cal…
The durability of basalt fibres reinforced polymer (BFRP)
2014
The technology of dry assembly for the production of multi-layer panels has evolved over the past 30 years, becoming an efficient alternative to traditional systems. The direction taken by the market has been increasingly drawn to eco-sustainable systems and in this way, the interest in the use of laminated composite panels for cladding, basalt fibres based. Basalt is a natural rock, silica based, which is produced through a variety of industrial processes into filaments, wool, chopped strands and fabrics. It is characterized by high resistance in chemically aggressive environments, high fire resistance, high mechanical resistance to compression and bending. The study focuses on two types o…