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Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends

An understanding of the crystallization process kinetics is important for the selection of processing parameters and product properties control. In this study, the isothermal crystallization of polypropylene/polystyrene/styrene-ethylene-butadienestyrene (PP/PS/SEBS) blends were evaluated using diffe...

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Main Author: Selamat, Nur Zalina
Format: Thesis
Language:English
Published: 2015
Subjects:
TP Chemical technology
Online Access:http://eprints.utm.my/id/eprint/53928/25/NurZalinaSelamatMFKChE2015.pdf
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spelling my.utm.539282020-10-08T04:20:12Z http://eprints.utm.my/id/eprint/53928/ Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends Selamat, Nur Zalina TP Chemical technology An understanding of the crystallization process kinetics is important for the selection of processing parameters and product properties control. In this study, the isothermal crystallization of polypropylene/polystyrene/styrene-ethylene-butadienestyrene (PP/PS/SEBS) blends were evaluated using differential scanning calorimetry (DSC). The blends were prepared by using Brabendar twin screw extruder and samples were then injection molded. 10-15 mg samples were quenched from the melt stage to a range of crystallization temperatures (Tc) between 134-138 C. That samples were held at these selected temperatures until the calorimeter response returned to the baseline. Isothermal crystallization data were then analyzed using Avrami kinetics model and Hoffman-Weeks theory. The increase of amorphous PS and SEBS content in system blends led to the decreases in the crystallization rate. The region covered for Avrami exponent, n, was between 1.97 to 3.2 (±0.1), indicating that heterogeneous nucleation of spherulites occurred and the growth of spherulites was between two-dimensional and three-dimensional for primary crystallization process of the blends. Equilibrium melting temperature (Tm°) obtained through Hoffman-Weeks theory was found to decrease with increasing PS and SEBS contents. The presence of amorphous polymer could disrupt the packing of the crystalline component in the blend, resulting in defective, lower melting point crystallites. The mechanical properties determined from tensile, flexural and impact test revealed that loading of SEBS gave a synergistic effect on flexural properties, and higher loading of SEBS produced superior impact properties. The best stiffness– toughness balance was obtained from the blend of PP/PS 90/10 at 5 phr SEBS loading which also gave fastest crystallization. Morphology studies by scanning electron microscope (SEM) showed finer dispersion of PS with the presence of SEBS into PP/PS blends. SEBS confirmed the improvement of blend compatibility. 2015-02 Thesis NonPeerReviewed application/pdf en http://eprints.utm.my/id/eprint/53928/25/NurZalinaSelamatMFKChE2015.pdf Selamat, Nur Zalina (2015) Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends. Masters thesis, Universiti Teknologi Malaysia, Faculty of Chemical Engineering. http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:85454
institution Universiti Teknologi Malaysia
building UTM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Teknologi Malaysia
content_source UTM Institutional Repository
url_provider http://eprints.utm.my/
language English
topic TP Chemical technology
spellingShingle TP Chemical technology
Selamat, Nur Zalina
Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends
description An understanding of the crystallization process kinetics is important for the selection of processing parameters and product properties control. In this study, the isothermal crystallization of polypropylene/polystyrene/styrene-ethylene-butadienestyrene (PP/PS/SEBS) blends were evaluated using differential scanning calorimetry (DSC). The blends were prepared by using Brabendar twin screw extruder and samples were then injection molded. 10-15 mg samples were quenched from the melt stage to a range of crystallization temperatures (Tc) between 134-138 C. That samples were held at these selected temperatures until the calorimeter response returned to the baseline. Isothermal crystallization data were then analyzed using Avrami kinetics model and Hoffman-Weeks theory. The increase of amorphous PS and SEBS content in system blends led to the decreases in the crystallization rate. The region covered for Avrami exponent, n, was between 1.97 to 3.2 (±0.1), indicating that heterogeneous nucleation of spherulites occurred and the growth of spherulites was between two-dimensional and three-dimensional for primary crystallization process of the blends. Equilibrium melting temperature (Tm°) obtained through Hoffman-Weeks theory was found to decrease with increasing PS and SEBS contents. The presence of amorphous polymer could disrupt the packing of the crystalline component in the blend, resulting in defective, lower melting point crystallites. The mechanical properties determined from tensile, flexural and impact test revealed that loading of SEBS gave a synergistic effect on flexural properties, and higher loading of SEBS produced superior impact properties. The best stiffness– toughness balance was obtained from the blend of PP/PS 90/10 at 5 phr SEBS loading which also gave fastest crystallization. Morphology studies by scanning electron microscope (SEM) showed finer dispersion of PS with the presence of SEBS into PP/PS blends. SEBS confirmed the improvement of blend compatibility.
format Thesis
author Selamat, Nur Zalina
author_facet Selamat, Nur Zalina
author_sort Selamat, Nur Zalina
title Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends
title_short Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends
title_full Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends
title_fullStr Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends
title_full_unstemmed Isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends
title_sort isothermal crystallization study and mechanical properties of polypropylene/polystyrene/styrene-ethylenebutadiene- styrene blends
publishDate 2015
url http://eprints.utm.my/id/eprint/53928/25/NurZalinaSelamatMFKChE2015.pdf
http://eprints.utm.my/id/eprint/53928/
http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:85454
_version_ 1681489451028578304
score 13.211869

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