Dependence of morphology and crystallization parameters of polypropylene on nucleation

Janevski, Aco and Bogoeva-Gaceva, Gordana (2014) Dependence of morphology and crystallization parameters of polypropylene on nucleation. In: First Symposium - Research in the Field of Environment and Materials, 21-22 Nov 2014, Macedonian Academy of Science and Arts.

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The rate of crystallization of isotactic polypropylene (iPP) at a given temperature, likewise the other crystallizing polymers, depends on the number of active centers from which the crystal growth begins, i.e. on the density of nuclei. In this paper the nucleation characteristics of some additives and reinforcements for iPP, which are mainly applied in the manufacturing of iPP based composites, have been investigated. The glass fibers, incorporated in the polymer in amount of 30-50 wt %, are shown to increase the nucleation density insignificantly, and they represent weak -phase nucleators for iPP. The presence of talc in iPP, even in amount of 0.1wt %, increased the nucleation density of the polymer for about 17 times. Equilibrium melting temperature (Tmo) of nucleated iPP, decreases from 465.7 K to 447.7 K with increasing of nucleation density, and the ratio of the initial and final dimensions of the lamella (l / l*) increases up to 4 times. The function of heterogeneous nucleation (θ) depends on the density of nucleation, and it was found that by increasing the density, the heterogeneous nucleation ability increases. Additives which cause epitaxial crystallization of iPP exibited lower value of θ-function and higher nucleation density. The structure of iPP created in the presence of strong nucleating agents is less susceptible to recrystallization, compared with the structure that occurs in the absence of nucleators or in the presence of weak nucleating agents.

Item Type: Conference or Workshop Item (Speech)
Subjects: Natural sciences > Chemical sciences
Natural sciences > Other natural sciences
Natural sciences > Physical sciences
Divisions: Faculty of Technology
Depositing User: Aco Janevski
Date Deposited: 26 Nov 2014 10:06
Last Modified: 26 Nov 2014 10:06

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