The effect of various β-nucleating agents on the morphology of 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

The effect of various β-nucleating agents on the morphology of polypropylene

Original language description

Isotactic linear polypropylene (iPP) is a semi-crystalline polymer with versatile applications, excellent mechanical properties, and cost-effectiveness. It is distinguished by its low density, high melting point, and exceptional chemical resistance, making it an essential material in modern times. Isotactic linear polypropylene displays a polymorphic structure, exhibiting well-defined distinct phases, including α, β, γ, and smectic phases, which are formed during high undercooling [1]. The monoclinic α-phase is formed during regular processing conditions and presents two variants, α1 with random down-up directions of methyl groups, and α2, a more stable form with ordered methyl groups. The β-phase can be achieved by creating favourable crystallization conditions, such as high temperature gradient, the presence of shear forces, or using heterogeneous β-nucleating agents (NA), resulting in a trigonal lattice. The β-phase displays improved toughness and ductility but is less stable than the α-phase and can recrystallize into the latter upon stretching at high temperatures [2, 3]. In this study, the effect of β-nucleation using various nucleating agents on the crystallization, thermal properties and supermolecular structure of iPP were studied with comparison to non-nucleated iPP. Additionally, the effect of shear-induced crystallization is studied. The three β-nucleating agents, namely, calcium pimelate (PP+CaPim), zinc phthalate (PP+ZnPht) and γ-quinacridone (PP+γ), were mixed into the iPP and then injection moulded or compressed moulded. The morphology was analysed using differential scanning calorimetry including flesh type, wideangle X-ray scattering, microscopy techniques and mechanical testing. Figure 1 shows the photos of supermolecular structure taken from scanning electron microscopy (SEM): the effect of nucleating agent can be seen. All nucleating agents used significantly affected the process of crystallization. When material undergoes injection moulding, the amount of β-phase increases, in this case, the highest amount of β-phase has the material containing NA calcium pimelate, the lowest γ-quinacridone. This study shows that the most effective β-nucleating agent is calcium pimelate in samples processed by injection moulding.

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