LEAL, T. L.; http://lattes.cnpq.br/1894550110012250; LEAL, Tânia Lúcia.
Résumé:
There is a strong industrial interest on the development of polymer blends as this
is a low cost and efficient method to modify polymer properties. The appropriate
choice of components allows the adjustment of the properties of the blend to
specific needs.
Nowadays the use of biomass derivatives by the chemical industries is growing
steadily as these vegetable products and byproducts come from renewable
sources and are substituting petroleum based products.
In the present work, unsaturated polyester/polyurethane blends (UP/PU blends)
were developed with the aim to produce tougher polyester based products. Blends
of a single commercial unsaturated polyester and three different polyurethanes
were investigated. The polyurethanes employed in this work come from natural
sources and were obtained by reacting poliols, derived from castor oil, having
distinct hydroxyl content, with an isocyanate capped pre-polymer also derived from
castor oil.
The mechanical properties (tensile and impact) of the blends were investigated as
a function of polyurethane kind and content as well as of post-curing for one hour
at two different temperatures (80 and 150°C). The blends were visually inspected
and characterized by fourier transform infra-red spectroscopy (FTIR) and their
fracture surfaces analyzed by scanning electron microscopy (SEM).
The results obtained indicate that tougher polyester based products can be
obtained by blending with polyurethane and that, in general, for the systems under
investigation: 1) both the tensile and the impact strengths of the blends which were
not post-cured, tended to increase with the reactivity (hydroxyl content) of the
polyol employed in the synthesis of the polyurethane employed; 2) the modulus
and the elongation at break were not dependent on the kind of PU used; 3) there
was strong phase segregation at higher (15%) PU contents; 4) the properties of all
systems investigated tended to decrease with post-curing at high (150°C)
temperatures; 5) better overall mechanical properties were obtained for the
systems post-cured for 1h at 80°C and 6) optimized impact properties were
achieved for the blends with 10% PU content.