Blendas de poli (tereftalato de etileno)/copolímeros: estudo por reometria de torque, propriedades mecânicas, térmicas, reológicas e morfologia.

Abstract

In this work a preliminary study by torque rheometry of the interactions between the poly (ethylene terephthalate) terminal reactive groups and the functional groups of six copolymers (EBAgMA, EGMA, EMAGMA, PEgAA, PEgMA and SEBSgMA) was carried out. Afterwards, the influence of the two copolymers (EGMA and EMAGMA) that presented highest torque values in the previous study, on the properties of Poly (ethylene terephthalate) (PET)/copolymer blends was investigated. For PET/EGMA and PET/EMAGMA blends, rheological analyzes were performed by torque and oscillatory rheometry, tensile and impact tests and characterizations by FTIR, DSC, DMTA, TG, XRD and SEM. The results, obtained from torque rheometry, showed a considerable increase in torque with the addition of EGMA and EMAGMA to the PET matrix, which was attributed to the reactions between the groups present in the copolymers and the terminal groups of PET. The mechanical properties of PET/ EGMA and PET/EMAGMA blends showed good balance between stiffness and flexibility. FTIR analyzes indicated the possible chemical reactions between the EGMA and EMAGMA polar groups with those of PET in the blends studied. Thermal analyzes by DSC, DMTA and TG indicated that PET/EGMA blends are more crystalline, rigid and more thermally resistant than PET/EMAGMA blends. The rheological measurements under oscillatory shear flow showed that the addition of these two copolymers increased the viscosity of the PET at low frequencies, suggesting that the reactions led to structural changes or increase of the molecular mass by chain extension and/or branching. SEM analysis showed no significant increase in the average size of the dispersed phase domains of the two copolymers (EGMA and EMAGMA) studied with increasing concentrations. This was probably due to the chemical reactions between the functional groups of the PET and the functional groups present in the modifiers, forming a copolymer at the interface and suppressing the coalescence between the modifying particles.