engleski

Stress Relaxation and Dynamic Mechanical Behaviour of PS-HI/SEBS Blends

For the selection of the polymer materials and polymer blends for various fields of applications the dynamic mechanical properties as well as the stability of materials under constant deformation are very important.In this paper, the copolymers high -impact polystyrene, PS-HI, and styrene-ethylene/butylene-styrene block copolymer, SEBS, and their blends PS-HI/SEBS were investigated.Since the polymer materials are viscoelastic, their mechanical properties are dependent on temperature and time.The investigation were done by DMA analysis.The primary viscoelastic functions were determined in the temperature range from -100 to 160 oC.The influence of the constant deformation on the PS-HI , SEBS and their blends was examined.The stress relaxation was performed at temperatures 25, 30, 35, 40 and 45 oC and the time-temperature correspondence principle was applied to create master curve.These results enable us to predict the useful time of the investigated blends.The results obtained show that primary viskoelastic functions, E', E" and tan delta as well as stress, depend on the amount of the hard phase, PS ans soft phase in PS-HI/SEBS blends as well as time and temperature and are due to the structural characteristic of examined systems and their changes in the conditions of the investigations.

Styrene copolymers blends; dynamic mechanical properties; relaxation process; constant deformation; useful time prediction

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