Search results for "COMPOSITE"
showing 10 items of 4584 documents
Mechanical properties of carbon nanotube reinforced nanocomposites
2013
One way to take advantage of the marvelous properties of the carbon nanotubes consists in incorporating them into a matrix to build composite materials. The best candidates for this task are undoubtedly polymers thanks to their strength, toughness, low weight, and easy processing. A mixed model, numerical-analytical, is presented that allows one to predict the elastic properties of carbon nanotube (CNT)/polymer composites containing a random distribution of CNTs, while taking account of the curvature that they show when immersed in the polymer. A three-dimensional model, using a single CNT immersed in an infinite matrix, allows us to numerically evaluate the concentration tensor by evaluati…
Construction stages of cable-stayed bridges with composite deck
2012
A cable-stayed bridge is built by following a construction sequence of different subsequent stages that imply changes of the geometric configuration, restraints and consequently stress and strain patterns. A study is presented about stay stressing sequences in cable-stayed bridges with composite deck for the case of construction made by the cantilever method. Initial cable forces are found through partial elastic schemes of construction stages. Different stay stressing procedures are implemented and a comparison between them is proposed in order to evaluate the differences in terms of deformed shape and internal force distribution of the deck and the pylon. Results can be useful to give pra…
Recycling mussel shells as secondary sources in green construction materials: a preliminary assessment
2023
This paper reports the development of novel green bio-composite mortars obtained by reusing mussel shells, a waste from the fish canning industry, as recycled aggregate, used for the first time in total substitution to the traditional sand. It suggests that this is a valid alternative to their usual disposal in landfills because the organic matter is potentially dangerous to humans and the environment. Different waste-based cementitious mixes were tested and compared to a traditional OPC mortar. The manufacturing process was performed at ambient conditions (20 °C, 65% RH) with highly sustainable results and consisted of simple operative steps reproducible in a real building site. The engine…
Application of Silsesquioxanes in the Preparation of Polyolefin-Based Materials
2023
This paper is a review of studies on the use of the polyhedral oligomeric silsesquioxanes (POSS) of various structures in the synthesis of polyolefins and the modification of their properties, namely: (1) components of organometallic catalytic systems for the polymerization of olefins, (2) comonomers in the copolymerization with ethylene, and (3) fillers in composites based on polyolefins. In addition, studies on the use of new silicon compounds, i.e., siloxane–silsesquioxane resins, as fillers for composites based on polyolefins are presented. The authors dedicate this paper to Professor Bogdan Marciniec on the occasion of his jubilee.
IN-LINE MONITORING OF THE PHOTOOXIDATION BEHAVIOUR OF PP/CLAY NANOCOMPOSITES THROUGH CREEP MEASUREMENTS
2016
The photooxidation of polymer systems is usually investigated by monitoring the change of chemical and molecular structure, morphology and macroscopic after a given period of UV exposition. In a previous paper, La Mantia et al. [1] presented a new apparatus that is able to monitor during the accelerated weathering the effect of the photooxidation on a polymer sample subjected not only to temperature, humidity and UV irradiation, but also to a mechanical stress, fully simulating real working conditions for plastic products. In this work, a polypropylene/organomodified clay nanocomposite has been subjects to the same test and the results compared with those obtained for the pure matrix.
Photooxidation behaviour of LDPE/Clay nanocomposite measured through creep curves
2016
The creep response of Polymer systems is typically investigated upon applying different loads, or under different temperature. However, no evidence exist of creep studies under different loads and temperatures and the simultaneos actionof accelerated weathering. In a previous paper La Mantia et al. [1] presented a new equipment that is able to subject polymer samples to creep under different loads, but also monitor the effect of photooxidation due to the temperature, humidity and UV irradiation, thus fully simulating the real operating conditions for polymer-based items. In tihs work a polyethylene/organomodified caly nanocompositehas been subjectedto combined creep-accelerated weathering c…
Synthesis and self-assembly of a PEGylated-graphene aerogel
2016
Abstract In the frame of this work, we present, for the first time, the synthesis and self-assembly of an aerogel built by graphene oxide-polyethylene glycol. The synthetic route involves at first the coupling of GO with an amino-terminated polyethylene glycol sample by carbodiimide in aqueous environment, and the subsequent conversion of the hydrogel achieved into an aerogel via freeze-drying. The 3D PEGylated graphene-based aerogel, characterized by spectroscopic, morphological, structural and mechanical analyses, displays an ultralight and highly porous (99.7%) network and possesses high mechanical properties together with a good biocompatibility.
Effect of Multi-Impact on Qiqh Carbon/Epoxy Composite LaminateEffect of Multi-Impact on Qiqh Carbon/Epoxy Composite Laminate
2018
This work is motivated by increasingly used of composite structures under severe loading conditions. During their use, these materials are often subjected to impact as for example, in the aeronautical field the fall of hailstone on structure composites. In fact, the low energy traditional impact tests don’t allow to see the evolution of the damage and don’t permit also to compare the best tolerance to impact between different stratifications. The multi-impact tests made it possible to find a solution to this problem. In this work, multi-impact tests are performed on three carbon/epoxy stratifications. The final goal is to predict the durability of the composite structures during impact load…
An analytical review of destination competitiveness´ indicators
2015
The role of indicators in assisting tourism planners and decision-makers in evaluating performances, setting targets and anticipating future scenarios has been widely acknowledged by scholars. The purpose of this study is to provide an evaluation of existing composite indicators of tourism destination competitiveness (TDC) and propose a statistical toolbox/protocol to assess their effectiveness in empirical evaluations. We built the study’s protocol by enriching the OECD technical guidelines to build composite indicators. The protocol contains now 15 criteria used to examine the reviewed indicators, among these two useful quality measures. Ten studies were identified as providing a composit…
Polytetrafluoroethylene Films in Rigid Polyurethane Foams' Dielectric Permittivity Measurements with a One-Side Access Capacitive Sensor.
2021
As a non-metallic composite material, widely applied in industry, rigid polyurethane (PUR) foams require knowledge of their dielectric properties. In experimental determination of PUR foams’ dielectric properties protection of one-side capacitive sensor’s active area from adverse effects caused by the PUR foams’ test objects has to be ensured. In the given study, the impact of polytetrafluoroethylene (PTFE) films, thickness 0.20 mm and 0.04 mm, in covering or simulated coating the active area of one-side access capacitive sensor’ electrodes on the experimentally determined true dielectric permittivity spectra of rigid PUR foams is estimated. Penetration depth of the low frequency excitation…