Preparition And Properties Of H-HIPS/PE Blends

First of all, HIPS, dissolved in the cyclehexane, was homogeneously and selectively catalytic hydrogenated using a Ziegler-Natta type catalyst, which was prepared with nickel naphthenate(Ni) and alumimum trisobutyl(Al),at4MPa H2pressure. The effects of the solvent, the amount of catalyst, the reaction temperature and the reaction time on the degree of hydrogenation of HIPS, were investigated.The results showed that, HIPS with the best degree of hydrogenation was obtained at60℃, a molar ratio of Al to Ni equal to5:1, and the reaction time was3h. The crystallizing melting peak appeared in DSC curve, and the crystallizing peak was on the XRD curve. By1H-NMR, protons of C=C double bond of PB disappeared on the’H-NMR curve after hydrogenating. The tensile strength of H-HIPS/LLDPE blend increased from31.64MPa to48.91MPa; the impact strength decreased from31.26KJ/m2to7.35KJ/m2.Second, HIPS/LLDPE, HIPS/LLDPE/SEBS and H-HIPS/LLDPE blends were prepared. The mechanical properties、the mobility and microscopic structure of the blends were studied with stretching, bending and impact experiments, melt index test, scanning electron microscopy (SEM), DSC and other methods. The effects of the composition of the blends were investigated on mechanical and processing properties of various systems. And the same proportions were compared with the performance of different blends.The results showed that, HIPS/LLDPE were not compatible at all. The mechanical properties of the blends were improved with five pieces of SEBS. To HIPS/LLDPE (70/30) blend, the impact strength increased from7.55KJ/m2to11.87KJ/m2.To H-HIPS/LLDPE blends, the better the mechanical properties were, the more the compositions of H-HIPS were. And on the XRD curve, the crystallizing peaks were weaker when the contents of H-HIPS were higher.Scanning electron microscope image shows:the section of H-HIPS/LLDPE(70/30) blends was rough, interface was fuzzy, and the dispersive property was better, indicating that the degree of adhesion between the two-phase was high. The double crystallizing melting peak appeared in DSC curve, and the melting point was low. The mechanical properties were better than HIPS/LLDPE/SEBS. The tensile strength was22.95MPa, the elongation at break was17.08%, and the impact strength was12.78KJ/m2. By rheological curves, the lower the shear viscosity was, the higher the shear rate was.The conclusion was that the compatibility between HIPS and LLDPE was improved when HIPS was hydrogenated.