Résumé:
The results obtained show that the coefficient of thermal expansion of the nanocomposite
PE+X%CNT is changed between the radial direction and the longitudinal one, whatever the
concentration of carbon nanotubes.
According to the radial direction, is higher than the coefficients in the whole of the
of temperature domain. According to the longitudinal direction, the dilatometric behaviour of the
nanocomposite changes completely. Pure polyethylene presents a thermal expansion coefficient
very large in comparison to that of the three others. The four curves contain each one a dilatometric
anomaly. Its intensity depends on the concentration.
We notice that the thermal expansion coefficient as well as the intensity of the dilatometric anomaly
of the nanocomposite EP+1%CNT is the weakest one in front of the three others whatever the
direction of measurement.
The curves of differential scanning calorimetry of the four samples have the same form and the
shapes are practically confused. They contain each one a calorimetric anomaly appearing at 95°C.
Thermogravimetric measurements of the two nanomaterials containing respectively 1 and 2.5%
NTC give curves which overlap and have intensities appreciably the same ones. As for the sample
containing 0.5% NTC, its TG is very intense in front of the two other nanocomposites and that of
pure material on all the studied temperature range.
The Raman spectroscopy, of the studied samples, reveal that the intensities of the various peaks
present on the four curves strongly vary according to the concentration in nanotubes. The curves of
the pure sample and the nanocomposite EP+0.5%CNT are superposable. As for the spectra of two
other nanomatérials containers 1 and 2.5%CNT, they have the same form and are superposable.
The two spectra contain the same number of anomalies and appear at the same frequencies. The
Raman intensity of the nanomaterial PE2.5%CNT is lower than the three others.
The spectra obtained by the infrared illustrate an important intensification due to the introduction
of the carbon nanotubes into polyethylene. The shapes of the curves of the three nanocomposites,
whatever the concentration in multiwalled carbon nanotubes, changed form and became more
intense in comparison to that of pure polyethylene. That of nanomaterial PE+1%NTC have the
greatest intensity.
The use of several experimental techniques for the realization of this work made it possible to
highlight and to confirm the positive role of the carbon nanotubes introduced into polyethylene.
The results obtained in this thesis are of an unquestionable contribution in the field of sciences of
materials. Dilatometry enabled us to show that the nanocomposite containing 1%NTC has a low
thermal dilation coefficient according to the temperature. This behaviour makes it interesting in the
industrial field. The mechanical tests confirmed that the injection of carbon multiparois nanotubes
in polyethylene made increase the elastic range. The Raman spectroscopy showed that the increase
in the concentration in carbon multiparois nanotubes in polyethylene high density PEHD makes
decrease the quantity of defects, improves qualities of the nanocomposite, reinforces the C-C bonds
and led to an ordered structure.
