ARAÚJO, J. P.; http://lattes.cnpq.br/5126842862206600; ARAÚJO, Jeane Paulino de.
Résumé:
The poly(lactic acid) (PLA) has attracted great interest from both academia and
industry mainly due to its biodegradability, some attractive mechanical properties and
because it is synthesized from raw materials from renewable sources. However, PLA
has some drawbacks such as high brittleness, low crystallization rate, sensitivity to
moisture, and deterioration at high temperatures, which limit its applications and
compromise its processing and final performance, needing to be modified, so it can
meet market expectations. Thus, the modification of PLA was carried by blending it
with polyethylene grafted with acrylic acid (PEgAA), assessing the reactivity between
the functional groups of the two polymers and the effect of different PEgAA
copolymer content on the properties of PLA/PEgAA blend. PLA/PEgAA blends
containing 5, 10, 15 and 20% (wt) of PEgAA were prepared in a co-rotational twinscrew extruder, and characterized by Fourier transform infrared spectroscopy (FTIR),
differential scanning calorimetry (DSC), dynamic mechanical thermal analysis
(DMTA), mechanical properties, scanning electron microscopy (SEM), X-ray
diffraction (XRD) and rheological measurements. FTIR results indicated that a
polyesterification reaction between the hydroxyl groups of PLA and the carboxyl
groups of PEgAA has occurred. DSC and DMTA analyses indicated that the addition
of PEgAA to PLA led to the decrease in both the glass transition (Tg) and the cold
crystallization (Tcc) temperatures. The PEgAA domains size increased with the
increase in the PEgAA content. With the addition of PEgAA there was a slight
increase in the impact strength of the blends containing 5 and 10% of PEgAA, when
compared to that of neat PLA. The PLA/PEgAA blend containing 15% (wt) of PEgAA
presented the highest complex viscosity and storage modulus at low frequencies.
