Study on the Crystallization Behavior of Nucleated Polypropylene under Shear at Isothermal Conditions
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Thermoplastic Polymers show big changes in their solidification behavior, orientation and crystallization when they are processed under different conditions. These also alter the mechanical properties of the polymer. An experimental study was performed to show the effect of shear stress, total shear, additive concentration and temperature on crystallinity, orientation and solidification time. The solidification process and therefore the solidification time of the samples without additives was traced by measuring the transmission of light through the sample by an optical system containing a laser, an analyzer and a photodiode detector. The solidification was supposed to be completed when the transmittance was approximately zero. The total shear was controlled manually and obtained by a displacement transducer. The samples from the shear experiments were cut with a microtome perpendicular and parallel to the shear direction. Subsequently, the morphology and orientations were analyzed using polarization microscopy.