1,721,258 research outputs found
Sintering of powders from fiberglass recycling
No full textSintering is a typical process for metal powders which can be effectively agglomerated by a solid state diffusion mechanism. Polymer powders are less sensible to this kind of mechanism because of the lower molecular mobility. Anyway, such applications have been mentioned about sintering of thermoplastic powders in the scientific literature. In this study, sintering has been used for the first time to agglomerate thermoset powders coming from recycling of fiberglass. This way, two interesting results have been obtained. First of all, new products have been produced by recycling fiberglass without any addition of virgin resin or linking agent. Moreover, it has been shown that sintering can lead to very high thickness products which are very difficult to obtain by typical molding processes because of shrinkage or frozen stresses. In order to show the feasibility of this new process, some powders have been collected from the waste of industrial partners. These powders have been molded without the addition of any other material so as to produce small plates or thick bricks. In such cases, a polyester coating was also added to improve the surface quality of the brick. Several samples have been extracted from these products and tested to evaluate the mechanical performances of the recycled plates. Results are very promising in terms of process easiness and part properties. A density about 1 g/cm3 has been obtained with a flexural modulus about 1 GPa and a flexural strength up to 20 MPa
Conceptual design of an experiment for the international space station about cosmic ray shielding materials
No full textCosmic ray (CR) shielding is the main issue for future long missions far for the protection of the Earth's magnetic field. Many experiments have been performed in Space to evaluate the effect of the Space environment on the material stability (mainly MISSE experiments from NASA). However those experiments were not able to evaluate CR shielding performances of materials, and results are mainly present in the form of erosion yield due to atomic oxygen erosion. In this study, a conceptual design is shown for further experiments on the International Space Station by focusing on the effect of cosmic rays on material aging. Shields will be made by using polyolefin sheets coupled or not with metallic foils. Polymeric sheets will be filled or coated with magnetic nano-particles to provide a small magnetic activity
Anisogrid lattice structure in thermoplastic composite by filament gun deposition
No full textA new method to manufacture thermoplastic composite parts has been used to produce anisogrid lattice structures. Filament gun deposition consists of a hot-melt gun loaded with narrow thermoplastic prepreg tapes. Anisogrid lattice structures have been prototyped with 3 different geometries and 5 different numbers of layers (from 4 to 8) by using a metallic pattern and E-glass/polypropylene prepregs. Scanning calorimetry and bending tests of multi-layer samples have been used to characterize thermoplastic prepregs. Anisogrid lattice structures have been tested under tensile loads. A finite element model has been used to predict mechanical stiffness of these structures by using material properties coming from the sample characterization. Numerical models have been developed with a batch-type parametric approach to rapidly evaluate the combined effect of geometric and material parameters. A good agreement has been found between experimental and numerical data with an average difference about 4%
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