The preparation of PLA and PC blends obtained by extrusion
with and without TA/TBATPBwas investigated. The addition of both
TA and TBATPB at 230 C resulted in improved compatibility
through the formation of a PLA-PC copolymer. In fact, a tan d trend
with a newpeakwas obtained by DMTA analysis. The new peakwas
situated between the Tg values of PLA and PC. The Tg of the copolymer
as a function of blend composition was consistent with the
models of Kwei [55] and Kalogeras [56].
The tensile characterization of physical PLA/PC blends showed
that the Young's modulus was improved as the PLA content was
increased. The maximum elongation at break was obtained as the
content of PC reached the percolation threshold, allowing the
achievement of a co-continuous phase morphology. More specifically,
the data fit well with two different predictive models. As the
catalyst was added, the Young's modulus of the materials increased
as a result of both the improvement of compatibility and chain
scission in the PLA phase, enabling the achievement of a cocontinuous
phase morphology for lower PC contents.
DSC and DMTA confirmed that, as the content of PC increased,
the crystalline fraction of the materials was reduced. More specifically,
in the PLA40/PC60eCAT blend, the typical decrease in
storage modulus due to the overcoming of Tg followed by the increase
due to crystallization was not observed, suggesting the
maintenance of mechanical stability at temperatures higher than
the Tg of PLA and the disabling of the crystallization process. The
effect is probably attributable to the links formed between PLA
and PC, which reduce PLA mobility. These advantageous properties
broaden the temperature range for applications of current materials
based on PLA.