engleski

Blends of PS/HDP with SEBS Block Copolymer as Compatibilizer

Polystyrene (PS) and polyethylene (PE) are two of the most widely used plastics in the world.The decrease of PS rigidity may be achieved with PE addition. In the same time the PE creep may be reduced with PS, what is specially important in recycled plastic, predominantly high density polyethylene (HDPE) used in constructions. But unfortunately PS and HDPE are incompatible in the whole composition ranges. An incorporation of proper compatibilizer reduces interfacial tension and leads to an improvement of mechanical properties of the final material. In this study styrene/ethylene/buthylene/styrene (SEBS) block copolymer is used as compatibilizer for PS /HDPE blends. The rheologycal properties of melt PS/HDPE blends in proccessing and rheologycal properties of extruded and moulded samles of the blends are investigated. The effect of the SEBS content on the morphology and mechanical properties of final material of the examined blends are provided. The rheological behaviour of the prepared blends during processing is followed by measuring the torque, output and melt pressure in a twin exstruder. Dynamical mechanical analysis was performed in temperature range - 1500C to 1500C. The blends were also investigated in creep fatigue regime and relaxations were determined. The morphology and mechanical properties of the blends are investigated by means of electron scanning microscopy, tensil behaviour and impact tests.With increasing HDPE content in PS/HDP blends the torque value decreases. When adding SEBS as compatibilizer the torque values are lower and decrease with the SEBS content. The curves of storage modulus E', loss modulus E'' and loss tangent tan vs. temperature are affected by increasing HDPE content. The creep values increase with HDPE contet in the blends. It is more expressed in the blends with compatibilaizer. Tensile strength of PS/HDPE blends as well as PS/HDPE/ SEBS blends decrease considerebly with increasing HDPE content while elongation on break and impact strength increase. The correlation between the microscopic morphology results, rheologycal and mechanical properties of the blends is discussed.

Polystyrene (PS); high density polyethylene (HDPE); PS /HDPE blends; styrene/ethylene/buthylene/styrene (SEBS) block copolymer; compatibilizer; rheologycal properties; morphology; dynamic mechanical analysis; mechanical properties

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