Polymer/halloysite nanocomposites : from nanoscale dispersion of untreated clay to flame retardancy of thermoplastic materials
(2013)
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- Authors
- Supervisors
- Bailly, Christian
- Abstract
- The nanocomposite approach has been identified as a promising route to meet the growing demand for polymers displaying unique combination of properties according to their respective application requirements. Most of the research conducted to date on polymer-clay nanocomposites has focused on the use of layered silicates. However, many other inorganic nanoparticles with peculiar geometries and intrinsic properties could offer alternatives to organoclays. In this context, the present thesis investigates the use of halloysite as a nanoreinforcement in thermoplastic materials. This work first explores routes for controlling and optimizing the dispersion of pristine halloysite nanotubes (HNTs) in melt blended polymers of different polarities. The use of water during extrusion promotes a nanoscale homogenization of the clay via a combination of physical and chemical effects. Next, structure-property relationships in these materials have been investigated in depth. Substantial improvements in mechanical, thermal and fire performances are observed when nanodispersion is achieved. The low flammability of HNTs-based nanocomposites in terms of heat release rate results from the build-up of an inorganic-rich surface layer limiting heat and mass transfers between gas and condensed phases. Highly loaded nanocomposite films coated on virgin polymer substrates can effectively speed up the barrier formation. However, nanocomposites fail other regulatory fire tests like UL-94. To overcome this problem, halloysite has been combined with intumescent systems. Results show that the aluminosilicate acts as a synergistic agent offering an unexpected way for making fire safe polymers.
- Affiliations
Citations
Lecouvet, B. (2013). Polymer/halloysite nanocomposites : from nanoscale dispersion of untreated clay to flame retardancy of thermoplastic materials. https://hdl.handle.net/2078.5/25279