Morphology and Properties of Annealed β-Nucleated Polypropylene

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Morphology and Properties of Annealed β-Nucleated Polypropylene

Popis výsledku v původním jazyce

The effect of molecular weight of isotactic polypropylene (iPP) and heat treatment on the final crystal structure and mechanical properties was investigated by wide-angle X-ray scattering (WAXS), differential scanning calorimetry, tensile tests and scanning electron microscopy. Two grades of iPP, produced by Borealis company, with melt flow index of 0.25 (BE52) and 8 g/10 min (HD-601CF) were used [1]. Both pure and β-nucleated (containing 0.03 wt. % of N,N´-dicyclohexylnapthalene-2,6-dicarboxamide, NJ Star NU 100) polypropylenes were subjected to annealing above the melting temperature of the β-phase but still below the melting temperature of the α-phase, causing both α-crystallite enhancement and β to α recrystallization, in the case of the nucleated material (Figure 1). As a result, the final mechanical properties such as tensile strength and stiffness were significantly improved (Figure 2). This increase is much more pronounced in the case of β to α-transformed materials with lower molecular weight (HD60-nu-an in Figure 2). In addition to the improvement of the crystalline phase, this phenomenon can also be attributed to the partial preservation of the specific structure of the amorphous phase present in β-nucleated polypropylene. The amorphous phase consists of many interconnected chains that pass through several lamellae, thus providing a long-range effect. To conclude, annealing at a temperature above the melting point of the β-phase has been confirmed as an effective way to improve the supramolecular structure and consequently the mechanical behaviour of annealed polypropylene.

Název v anglickém jazyce

Morphology and Properties of Annealed β-Nucleated Polypropylene

Popis výsledku anglicky

The effect of molecular weight of isotactic polypropylene (iPP) and heat treatment on the final crystal structure and mechanical properties was investigated by wide-angle X-ray scattering (WAXS), differential scanning calorimetry, tensile tests and scanning electron microscopy. Two grades of iPP, produced by Borealis company, with melt flow index of 0.25 (BE52) and 8 g/10 min (HD-601CF) were used [1]. Both pure and β-nucleated (containing 0.03 wt. % of N,N´-dicyclohexylnapthalene-2,6-dicarboxamide, NJ Star NU 100) polypropylenes were subjected to annealing above the melting temperature of the β-phase but still below the melting temperature of the α-phase, causing both α-crystallite enhancement and β to α recrystallization, in the case of the nucleated material (Figure 1). As a result, the final mechanical properties such as tensile strength and stiffness were significantly improved (Figure 2). This increase is much more pronounced in the case of β to α-transformed materials with lower molecular weight (HD60-nu-an in Figure 2). In addition to the improvement of the crystalline phase, this phenomenon can also be attributed to the partial preservation of the specific structure of the amorphous phase present in β-nucleated polypropylene. The amorphous phase consists of many interconnected chains that pass through several lamellae, thus providing a long-range effect. To conclude, annealing at a temperature above the melting point of the β-phase has been confirmed as an effective way to improve the supramolecular structure and consequently the mechanical behaviour of annealed polypropylene.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

10404 - Polymer science

Projekt

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Návaznosti

V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů