Influence of orientation on the relaxation and ultimate properties of polypropylene

摘要: As is known, the relaxation maxima of polymers are often shifted within time or temperature scale if materials stretched drawn. This behavior due to changes free volume and/or crystallization and orientation specimens. Since relations between these parameters shift not yet known very well, an examination was made using polypropylene as a suitable example. The knowledge technical importance, too, because accompaned by corresponding brittle-tough transitions. The were determined in good approximation measuring time-dependent moduli elasticity differentiating modulus curves. It found that main maximum shifts with increasing draw ratio longer times. At same activation energy decreases. Tensile tests, carried out on unstretched specimens, yielded transition maximum. molecular causes this discussed.