Análise reológica de misturas de PSAI com resíduos de espuma rígida de poliuretano

Ricardo Pedro Bom

Abstract


In this study the viscosity of pure high impact polystyrene (HIPS) and mixtures with rigid foam residues of polyurethane (PUR) was determined, through Melt Flow Index experiments (MFI), for shear rates between 3 and 20 s-1 at a temperature of 200ºC. Using equations that describe the flow in circular channels, and mass flow measures (MFI), the shear rate, the shear stress and the viscosity were calculated for pure HIPS at 200º C, with loads of 2,12; 3,77 and 4,97 Kg . The specific mass of pure HIPS at 23ºC was determined for MFI's transformation in volumetric flow. The rheologic curve of HIPS 495 F at 200ºC with MFI of 8,9 (g/10min), obtained through the Cross-WLF equation, was used as standard, and with the calculated results from the experiments, the correction index of Bagley (e) was determined. The flow index (n) used to make the Rabinovitsch's correction was determined from shear stress curve in the wall versus flow. Applying the average values of the correction indexes in the equations, it was possible to calculate the shear stress, the shear rate and the viscosity. The results of calculations, with and without the correction parameters (e, n), were represented graphically together with the standard rheologic HIPS curve, obtaining coherent values. Applying the same above procedure for HIPS with 5, 10, 15, 22, 30 and 40% of PUR with a load of 4,97 Kg and considering the same correction index of Bagley and of flow index, it was possible to describe the variation of the viscosity related to the shear rate for different compositions.

Key words: melt flow index, mass flow, polystyrene, polyurethane.

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ISSN: 1808-7310 - Best viewed in Mozilla Firefox

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