We have investigated the crystallization characteristics of melt compounded nanocomposites of poly(ethylene terephthalate) (PET) and single
walled carbon nanotubes (SWNTs). Differential scanning calorimetry studies showed that SWNTs at weight fractions as low as 0.03 wt% enhance
the rate of crystallization in PET, as the cooling nanocomposite melt crystallizes at a temperature 10 °C higher as compared to neat PET.
Isothermal crystallization studies also revealed that SWNTs significantly accelerate the crystallization process. WAXD showed oriented
crystallization of PET induced by oriented SWNTs in a randomized PET melt, indicating the role of SWNTs as nucleating sites.
Hysen, Thomas; Senoy, Thomas; Ramanujan, R V; Anantharaman, M R(Springer, 2008)
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Abstract:
Activation energy for crystallization (Ec) is a
pertinent parameter that decides the application potential of
many metallic glasses and is proportional to the crystallization
temperature. Higher crystallization temperatures are
desirable for soft magnetic applications, while lower values
for data storage purposes. In this investigation, from the
heating rate dependence of peak crystallization temperature
Tp, the Ec values have been evaluated by three different
methods for metglas 2826 MB (Fe40Ni38B18Mo4) accurately.
The Ec values are correlated with the morphological
changes, and the structural evolution associated with
annealing temperatures is discussed.
Poly(ethylene terephthalate) (PET) based nanocomposites have been prepared with single walled carbon nanotubes
(SWNTs) through an ultrasound assisted dissolution-evaporation method. Differential scanning calorimetry studies
showed that SWNTs nucleate crystallization in PET at weight fractions as low as 0.3%, as the nanocomposite melt crystallized
during cooling at temperature 24 °C higher than neat PET of identical molecular weight. Isothermal crystallization
studies also revealed that SWNTs significantly accelerate the crystallization process. Mechanical properties of the PETSWNT
nanocomposites improved as compared to neat PET indicating the effective reinforcement provided by nanotubes
in the polymer matrix. Electrical conductivity measurements on the nanocomposite films showed that SWNTs at concentrations
exceeding 1 wt% in the PET matrix result in electrical percolation. Comparison of crystallization, conductivity and
transmission electron microscopy studies revealed that ultrasound assisted dissolution-evaporation method enables more
effective dispersion of SWNTs in the PET matrix as compared to the melt compounding method
Anoop Anand,K; Dr.Rani,Joseph(Cochin University of Science & Technology, December , 2006)
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Abstract:
The current research investigates the possibility of using single walled carbon
nanotubes (SWNTs) as filler in polymers to impart several properties to the matrix
polymer. SWNTs in a polymer matrix like poly(ethylene terephthalate) induce
nucleation in its melt crystallization, provide effective reinforcement and impart
electrical conductivity. We adopt a simple melt compounding technique for
incorporating the nanotubes into the polymer matrix. For attaining a better dispersion
of the filler, an ultrasound assisted dissolution-evaporation method has also been tried.
The resulting enhancement in the materials properties indicates an improved
disentanglement of the nanotube ropes, which in turn provides effective matrix-filler
interaction. PET-SWNT nanocomposite fibers prepared through melt spinning
followed by subsequent drawing are also found to have significantly higher mechanical
propertiesas compared to pristine PET fiber.SWNTs also find applications in composites based on elastomers such as natural
rubber as they can impart electrical conductivity with simultaneous improvement in the
mechanical properties.
Description:
Department of Polymer Science and Rubber Technology,
Cochin University of Science and Technology