engleski

Modification of polypropylene/polystyrene blends with SEBS-g-MA block copolymer

Most of polymer blends are immiscible, so the addition of suitable chosen compatibilizer can modified interfacial characteristics when it locates at the interphase of two immiscible polymer components. In an immiscible polymer blend of isotactic polypropylene/atactic polystyrene, (iPP/aPS), the adhesion between phases is very week what results in poor stress transfer from polymer matrix to the dispersed phase. With the proper interfacial modification by compatibilizer it is possible to design useful polymer material with stable morphology and desirable final properties. The blend morphology depends on blend composition, interfacial tension, processing conditions, relative blend viscosity and relative elasticity of blend components. In this work, the effect of maleic anhydride grafted styrene-ethylene/butylene-styrene block copolymer (SEBS-g-MA) as compatibilizer in polypropylene/polystyrene blends (PP/PS) was investigated. Uncompatibilized and compatibilized blends were prepared by twin extruder in the whole range of the polymer component compositions. Dynamic-mechanical analysis (DMA) was performed to get insight of relaxation processes in complex multiphase systems PP/PS and PP/SEBS-g-MA/PS under the cyclic load. The interactions between phases and compatibility of polymer blends were followed through glass transition temperatures, intensities of relaxation maxima and storage modulus. Mechanical properties, tensile strength, elongation at break and yield were determined by Instron Mechanical Machine. Scanning electron microscope (SEM) was used to obtain the morphological structure of investigated systems as well as the effect of SEBS-g-MA block copolymer on reduction of domain size and particle dispersion in polymer blends. SEBS-g-MA block copolymer was found as a good compatibilizer for PP/PS blends as it decreased particle size of dispersed phase and coused finer morphology as well as better mechanical properties of

compatibilization; polymer blends; morphological strusture

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