Kinetical and thermodynamical parametars of crystallization of iPP nucleated with mixed α-nucleators

Janevski, Aco and Bogoeva-Gaceva, Gordana (2013) Kinetical and thermodynamical parametars of crystallization of iPP nucleated with mixed α-nucleators. In: 10th Symposium ”Novel technologies and economic development”, 22-23 Oct 2013, Leskovac, Serbia.

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Abstract

It is well known that the presence of a solid surface (substrate) in contact with thermoplastic polymers during the crystallization from the melt, generally favors the heterogeneous nucleation. Isothermal and nonisothermal crystallization of isotactic polypropylene (iPP) nucleated with 0.1 %wt. talc (average dimension of 20 µ) (assign. PPT), 0.1 %wt. calcite (average dimension of 5µ) (assign. PPC) and polymer nucleated with 0.1 %wt. talc plus 0.1 % wt. calcite (assign. PPTC), were studied to evaluate the different nucleation behavior of individual nucleators and their mixture. The nucleated systems were prepared on Brabender PL 2000, by melt-mixing at the 460 K. Morphological analyses of the obtained iPP was done by wide-angle x-ray diffraction and polarizing light microscopy. The crystallization behavior was studied by Perkin-Elmer DSC-7 in isothermal (Tc=391-403 K) and nonisothermal regime (applying cooling rate of 1,3,5,10,15 and 20 K/min). Induction times of crystallization were estimated, and from the Avrami plots which were linear for all systems, crystallization rate constants and coefficients were calculated. From the Hoffmann- Weeks plot, the equilibrium melting temperature was determined, and the lowest value is found for iPP nucleated with talc (Tmo was 447.6 K; for iPP nucleated with calcite Tmo = 462.3 K, and for iPP nucleated with the mixture of nucleators Tmo= 453.6 K. The peaks of nonisothermal crystallization were moved to higher temperatures, or lower supercooling, ΔT The best nucleation activity, has exhibited the system with talc, which is unexpected, because the highest content of nucleators was used in the system with both nucleators. These findings were confirmed by other thermodynamic parameters, such as dimension of a critical nucleus, nucleation density (highest value determined for this system) and -parameter (the lowest value of 0.35), which implies that interaction between polymer and substrate is highest in this system.

Item Type: Conference or Workshop Item (Poster)
Subjects: Engineering and Technology > Chemical engineering
Engineering and Technology > Materials engineering
Engineering and Technology > Other engineering and technologies
Natural sciences > Other natural sciences
Divisions: Faculty of Technology
Depositing User: Aco Janevski
Date Deposited: 15 Nov 2013 15:12
Last Modified: 15 Nov 2013 15:12
URI: http://eprints.ugd.edu.mk/id/eprint/8087

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