OLIVEIRA, A. D. B.; OLIVEIRA, AKIDAUANA DB.; DE OLIVEIRA, AKIDAUANA D. B.; http://lattes.cnpq.br/6096954242511758; OLIVEIRA, Akidauana Dandara Brito de.
Resumo:
The aim of this work is to evaluate the rheological behavior of high density
biopolyethylene/linear low density linear biopolyethylene (BioHDPE/BioLLDPE)
blends, containing 0-100% of BioLLDPE, at low and high shear rates and to correlate
the results with the molecular structure of individual polymers. It was observed from
complex viscosity curves (*) as a function of angular frequency () that the viscosity
of BioLLDPE, at low frequencies, is much higher than that of BioHDPE, which can be
attributed to the higher molar mass of BioLLDPE besides it has -oleophilic
branching of 1-butene type. The viscosity of the BioHDPE/BioLLDPE blend increased
with the increase of BioLLDPE content. Through the storage modulus (G ') vs ,
damping factor (tan ) vs and spectrum relaxation plots it was observed, at low
frequencies, that BioLLDPE is more elastic than BioHDPE and presented longer
relaxation time. For BioHDPE /BioLLDPE blends there was a monotonic increase of
G 'and reduction of tan slope with increasing BioLLDPE concentration, indicating a
more elastic behavior and resulting in longer relaxation times. Cole-Cole (imaginary
viscosity – ‖ vs real viscosity - '), Han (G' vs loss modulus - G‖) and van-Gurp
Palmen (phase angle - vs complex modulus G*) plots suggest that the BioHDPE
and BioLLDPE are possibly miscible in the molten state. It was observed that the
BioHDPE and BioLLDPE polymers in addition to the BioHDPE/ BioLLDPE blends
obey the principle of time-temperature superposition. BioHDPE/ BioLLDPE blends
with higher BioHDPE concentrations showed less extrudate swelling and less flow
instability. Based on the results it was observed that there is a strong dependence of
the rheological properties of the blends on the molecular structure of the individual
polymers and that the blends with higher contents of BioHDPE presented better
processability at the high shear rates.