Rheological Behaviour of Recycled and Virgin Polyethyleneterephthalate and Mixtures of Them

Different blends of virgin, recycled polyethyleneterephthalate (5-20 mass %) and their mixtures used for textile fibers were prepared. Their rheological characteristics were studied at temperatures 543, 548 and 553 K and shear stresses in the range from 6.2x10(3) to 14x10(3) Pa. Drawing the flow curves for the melts of the polymers studied using experimental data, it was found that they obeyed the power law at the three temperatures. A weak tendency of increase of the flow index was observed with the increase of temperature. The effects of two different stabilizers (Irganox 1076 and butylated hydroxytoluene BHT, 0.5 mass% vs. the polymer material) on the thermooxidative degradation were studied. The stabilizing ability of Irganox 1076 was found to be the better one since it increased viscosity from 50 to 100 Pa.s without any significant changes in polyethyleneterephthalate appearance. The influence of processing reiteration was studied for the individual polymers, as well as for their mixtures in different ratios.