Crystallisation behaviour of high density polyethylene blends with bimodal molar mass distribution
| Autor: | Anti Viikna, Arja Lehtinen, Andres Krumme |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Molar concentration
Molar mass Materials science Polymers and Plastics education Organic Chemistry technology industry and agriculture Analytical chemistry General Physics and Astronomy Polyethylene Crystallinity chemistry.chemical_compound Differential scanning calorimetry chemistry Polymer chemistry Materials Chemistry Molar mass distribution Mass concentration (chemistry) High-density polyethylene |
| Zdroj: | European Polymer Journal. 40:371-378 |
| ISSN: | 0014-3057 |
| DOI: | 10.1016/j.eurpolymj.2003.10.004 |
| Popis: | Crystallisation of high density polyethylene (HDPE) blends with broad bimodal molar mass distribution was investigated by differential scanning calorimetry (DSC) under non-isothermal conditions. The blends were prepared by blending a high molar mass PE (Mw=330 kg/mol, Mw/Mn=4.8) and a low molar mass linear PE (Mw=34 kg/mol, Mw/Mn=10) in different ratios in xylene solution. The samples were analysed by the normal DSC at different crystallisation rates and by a thermal fractionation technique. The blends and their parent polymers behaved according to general expectations i.e., crystallinity and density decreased when the molar mass of the samples increased. Additionally, non-linear relationships between MM and different analysed parameters were found. Small addition of the high molar mass parent polymer to the low molar mass parent polymer increased crystallisation temperature, although the general trend was decreasing. Furthermore, a complicated relationship between the reciprocal of crystallisation half-time and sample composition was found. The value increased first with increasing molar mass, reached a maximum when the average molar mass of the blend was between 150 and 200 kg/mol and then decreased. The detected maximum correlated with the broadest molar mass distribution of the blends. The crystallinities and densities of the blends with the broadest molar mass distribution also deviated from the linear correlation between them and molar mass. The Avrami index under non-isothermal conditions was analysed with a method developed by Harnisch and Muschik. The results indicated that thermal nucleation and spherical growth regimes are present in all studied materials. |
| Databáze: | OpenAIRE |
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