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Content archived on 2024-05-27

High performance damping material for aeronautical use (PARVIS)


This part of the research is focused on an innovating material not yet available in the market. Synthetic procedures must be optimised in order to both obtain the proper material with a reasonable yield and to facilitated their conversion to industrial scale. Polyphosphazenes are inorganic macromolecules that illustrate the possibilities available for a wide range of other inorganic systems. They comprise some of the most intensively studied inorganic macromolecules. Polyphosphazenes are high molecular weight, essentially linear polymers with alternating phosphorus and nitrogen atoms in the skeleton and two side groups attached to each phosphorus. Most polymers of this type resist burning or oxidative breakdown better than single strand organic polymers. Nearly all are highly stable to water and to a wide range of chemical agents. In overall performance, they are superior to the hydrocarbon rubbers and competitive with the silicones in applications that require stability over a broad temperature range. Depending on the type of the side groups of the polyphosphazene several elastomers can be obtained. Given the outstanding properties of the polyphosphazenes studied until now, the suitable development of a new type of this polymer designed for damping purposes.
This result is the experimental determination of the evolution of the viscoelastic parameters of all the materials produced by IQS, ISMANS and JEVSA. The viscoelastic parameters are specific characteristics of the material: the shear modulus G' is linked to the energy stocked by the material (elasticity) and the loss factor is linked to the energy dissipated by the material (heat transfer). This latter characteristic is the most important for our application as it is directly linked to the attenuation of vibro-acoustic levels. The results of these DMTA tests are the data, which are classically provided to demonstrate the damping performance of a material. Finally, as these tests were carried out on a large temperature range, it is possible to evaluate the stability of the performances against temperature variations. For the materials developed during PARVIS project, we can see that the damping performances are high but the temperature range of stability is not as large as expected.
A blend of well-known elastomers has been developed introducing new aspects regarding the formulation ingredients. The introduction of a plate-let filler in the formulation, and the combination of different polymers in the same formulation gave rise to new damping materials. This new formulation have been designed, elaborated, improved and characterised. The blend PARVIS-1/M shows good damping characteristics for low T. So it can be used as low temperature vibrations damping materials specifically suitable for applications requiring temperature independent performances. For instance automobile industry, building industry, household equipment. Actually we are producing the blends in a pilot plant and improving all the mixing and compounding parameters in order to get the optimum conditions .The advantage of this approach lies on the fact that the technology applied is very well-known and this will facilitate the subsequent transferring to the industrial level.
IPN's are essentially intimate mixtures of the cross-linked networks with no covalent bonds or grafts between them. For many investigators in the sound and vibration-damping field, IPN's are a new class of polymers capable of exhibiting relatively broadband damping properties. Whereas homopolymers and statistical copolymers damp effectively over narrow temperature ranges, typically 20-30ºC, IPN's constitute a class of multi-component polymeric materials that are capable of damping over broad temperature ranges of 100ºC. The idea came up as a way to combine the two approaches studied until this moment, i.e. the butyl rubber formulations and the IPN. A methodology was developed to chemically bond to the epoxy resin backbone, liquid polybutadiene chains. The pursued objective is to be able to combine all the good characteristic of the materials tested and put them all together within one single material. The polymeric material obtained with this type of modified epoxy resin consisted of an IPN of polyurethane and epoxy resin, showed good elasticity and tackiness. The material was analysed by DMA and the spectra obtained showed a rather significant broadening of the tan d peak. Furthermore, the value of tan d is rather high. This approach is based on the use of optimal blends of different materials polymerised at the same time, which would give rise to a perfect compromise of properties, enlarging the range where they can be used. The main idea would be to obtain a nanocomposite by adding mica as a filler that would enhance the damping performance of the material by introducing the SPADD philosophy within the material matrix itself.
A new polymeric material based on n butyl polyacrylates and a Latex Interpenetrated Polymer Networks (LIPN) have been designed, synthesised and characterised. The glass transition of the n butyl acrylate is 100°C. Between 80°C and 170°C, the tan d is 0.7 and shows a plateau like behaviour. The LIPN displays a mean tan d of 0.65 between -11°C and +122°C.With such properties, the n butyl polyacrylates material can be used as high temperature vibrations damping materials. Whereas the LIPN can be used in a more widen range of temperature. Both materials will be especially suitable for applications requiring temperature independent performances, for instance in aeronautic, civil engineering and automobile industries. Next steps in the R&D program include processing of laboratory samples, pilot unit set up and industrialisation with SPADD device as target application. Depending on the market spreading of SPADD system from now to 50 months, processing of laboratory samples step will be focused on study and selection of suitable processing technologies of latex film production. The pilot plan step aims at pre-industrialising materials production and processing for specific applications including SPADD device but also SSND, SDM etc. The work will consist in designing, manufacturing and testing.

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