Blendas de PHB e PETG : Formação de um copoliester aromatico/alifatico via processamento reativo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Blends of PHB and PETG produced in a batch mixer (Haake) and twin screw extruder are immiscible in the whole composition, as determined by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and field emission scanning electron microscopy (FESEM). Mechanical properties were evaluated by flexural and impact tests. The results revealed a increase in the flexural modulus in a 10 and 20% PETG blends, however the flexural strength shown a decrease. Blends processability were improved as PETG contents was increased mainly the injection molding . The immiscibility and compatibility of PHB/PETG blends can be changed through reactive processing in the molten state. Reactive mixtures were obtained through mechanical mixing using a batch mixer at compositions PHB/PETG 80/20 and 50/50. Reactions between PHB and PETG were induced by organometalic dibutyl tin oxide catalyst at 1, 3,6 and 9 wt% contents. FESEM shows that PETG domains are covered by a compatibililizer. Reactive blends were submitted to a solvent extraction in a Soxhlet apparatus, THF was used as solvent which is a good solvent to PETG but a non solvent to PHB. Two fractions were obtained: soluble and insoluble fractions, which were analyzed by several techniques. Soluble fractions were characterized by DSC, thermogravimetric analysis (TGA) , X-ray diffraction and nuclear magnetic resonance (NMR). DSC data shown a decrease in a PETG glass transition temperatura (Tg) as catalyst contents increase. TGA data showed that PHB content on soluble fractions increases as catalyst content increases. These results allow to conclude a copolymer syntheses during the reactive processing in the molten state. As catalyst amount increases the extension of reactions also increases for a constant time and temperature.

ASSUNTO(S)

biodegradação polimeros mistura (quimica)

ACESSO AO ARTIGO

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