Detail publikačního výsledku

Study of Secondary Crystallization of Isotactic Polypropylene via Pulsed 1H-NMR Method

VILČ, L.; KRATOCHVÍLA, J.

Originální název

Study of Secondary Crystallization of Isotactic Polypropylene via Pulsed 1H-NMR Method

Anglický název

Study of Secondary Crystallization of Isotactic Polypropylene via Pulsed 1H-NMR Method

Druh

Článek recenzovaný mimo WoS a Scopus

Originální abstrakt

Application of polymers depends significantly on the ability of their structure to remain unchanged as long as possible. Recrystallization processes as well as changes in amorphous fraction of semicrystalline polymers (such as isotactic polypropylene), induced by ageing, can alter the properties of the initial material. It is well known that the form and the portion of a crystalline phase are responsible for mechanical and physical properties of semicrystalline polymers. In this study, the crystallinity was characterized as a solid phase content (SPC) measured by pulsed 1H-NMR. Advantages of the method consist in a direct measurement, non-destructive character, high accuracy (standard deviation 0.03 %), high speed of analysis (a few minutes), fully automated and easy operation. Time and temperature dependence of SFC and relaxation times (T2s - spin - spin relaxation time of solid phase, T2l - spin - spin relaxation time of liquid phase) were assessed. The measurement was performed on several commercial available isotactic polypropylene materials. The maximum in the speed of the secondary crystallization on time was observed. It was discovered that T2s relaxation times were practically independent on time and temperature. However, T2l relaxation times depend on time and temperature significantly.

Anglický abstrakt

Application of polymers depends significantly on the ability of their structure to remain unchanged as long as possible. Recrystallization processes as well as changes in amorphous fraction of semicrystalline polymers (such as isotactic polypropylene), induced by ageing, can alter the properties of the initial material. It is well known that the form and the portion of a crystalline phase are responsible for mechanical and physical properties of semicrystalline polymers. In this study, the crystallinity was characterized as a solid phase content (SPC) measured by pulsed 1H-NMR. Advantages of the method consist in a direct measurement, non-destructive character, high accuracy (standard deviation 0.03 %), high speed of analysis (a few minutes), fully automated and easy operation. Time and temperature dependence of SFC and relaxation times (T2s - spin - spin relaxation time of solid phase, T2l - spin - spin relaxation time of liquid phase) were assessed. The measurement was performed on several commercial available isotactic polypropylene materials. The maximum in the speed of the secondary crystallization on time was observed. It was discovered that T2s relaxation times were practically independent on time and temperature. However, T2l relaxation times depend on time and temperature significantly.

Klíčová slova

polypropylene, pulsed 1H-NMR, secondary crystallization

Klíčová slova v angličtině

polypropylene, pulsed 1H-NMR, secondary crystallization

Autoři

VILČ, L.; KRATOCHVÍLA, J.

Vydáno

20.09.2005

Strany od

488

Strany do

489

Strany počet

2

Plný text v Digitální knihovně

http://hdl.handle.net/

BibTex

@article{BUT50659,
  author="Ladislav {Vilč} and Jan {Kratochvíla}",
  title="Study of Secondary Crystallization of Isotactic Polypropylene via Pulsed 1H-NMR Method",
  year="2005",
  pages="488--489"
}