Morphology and Properties of Annealed β-Nucleated Polypropylene

Result code in IS VaVaI

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Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Morphology and Properties of Annealed β-Nucleated Polypropylene

Original language description

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.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

10404 - Polymer science

Project

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Continuities

V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Publication year

2023

Confidentiality

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