eesti teaduste
akadeemia kirjastus
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of the estonian academy of sciences
ISSN 1736-7530 (Electronic)
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Behaviour of the very-low-temperature crystallization peak of linear low-density polyethylene; pp. 58–62

Full article in PDF format | doi: 10.3176/proc.2009.1.10

Triinu Poltimäe, Elvira Tarasova, Andres Krumme, Arja Lehtinen, Anti Viikna

The crystallization behaviour of Ziegler–Natta (ZN) and single-site catalyst based ethylene–1-butene and ethylene–1-hexene copolymers with different comonomer content were studied by differential scanning calorimetry. In addition to a high-temperature crystallization peak, and for ZN copolymers in addition to a low-temperature crystallization peak, quite often a very-low-temperature crystallization peak (VLTCP) was observed at temperatures in between approximately 330 and 345 K. It was found that the VLTCP temperature decreased with increasing comonomer content and did not depend on the type of catalyst used. The fractional degree of crystallinity calculated from the VLTCP was independent of the chemical nature and content of the comonomers present as well as of the polydispersity of molar mass within the used range of magnitudes. However, crystallinity as related to the area of the VLTCP was strongly catalyst type dependent and was higher for the single-site catalyst used compared to the ZN catalyst used.

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