This thesis is concerned with developing porous materials from tyre shred
residue and polyurethane binder for acoustic absorption and thermal insulation
applications. The resultant materials contains a high proportion of open,
interconnected cells that are able to absorb incident sound waves through
viscous friction, inertia effects and thermal energy exchanges. The materials
developed are also able to insulate against heat by suppressing the convection
of heat and reduced conductivity of the fluid locked in the large proportion of
close-cell pores. The acoustic absorption performance of a porous media is
controlled by the number of open cells and pore size distribution. Therefore, this
work also investigates the use of catalysts and surfactants to modify the pore
structure and studies the influence of the various components in the chemical
formulations used to produce these porous materials. An optimum type and
amounts of catalyst are selected to obtain a high chemical conversion and a
short expanding time for the bubble growth phase. The surfactant is used to
reduce the surface tension and achieve a homogenous mixing between the
solid particulates tyre shred residue, the water, the catalyst and the binder. It is
found that all of the components significantly affect the resultant materials
structure and its morphology. The results show that the catalyst has a
particularly strong effect on the pore structure and the ensuing thermal and
acoustical properties. In this research, the properties of the porous materials
developed are characterized using standard experimental techniques and the
acoustic and thermal insulation performance underpinned using theoretical
models.
The important observation from this research is that a new class of
recycled materials with pore stratification has been developed. It is shown that
the pore stratification can have a positive effect on the acoustic absorption in a
broadband frequency range. The control of reaction time in the foaming
process is a key function that leads to a gradual change in the pore size
distribution, porosity, flow resistivity and tortuosity which vary as a function of
sample depth. It is shown that the Pade approximation is a suitable model to
study the acoustic behaviour of these materials. A good agreement between the
measured data and the model was attained. / Ministry of Science and Technology of Thailand; Naresuan
University, Phitsanulok, Thailand,
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/5516 |
| Date | January 2011 |
| Creators | Mahasaranon, Sararat |
| Contributors | Horoshenkov, Kirill V., Benkreira, Hadj |
| Publisher | University of Bradford, School of Engineering, Design and Technology |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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