Reversible Melting of Thermally Fractionated Polyethylene |
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Authors: | Cser F Hopewell J L Shanks R A |
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Institution: | (1) CRC for Polymers, 32 Business Park Dr., Notting Hill, 3168;(2) Applied Chemistry, RMIT University, Melbourne, 3000, Australia |
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Abstract: | Different grades of linear low density polyethylenes (LLDPEs) have been quenched cooled step-wise and crystallised isothermally
at (a series of increasing) temperatures in a DSC (thermal fractionated samples). These samples have been investigated by
temperature modulated DSC (MDSC). The heat flow curves of the thermal fractionated materials were compared with those obtained
from samples crystallised at a relatively slow cooling rate of 2 K min-1(standard samples).
The melting enthalpy obtained from the total heat flow of the thermal fractionated samples was 0-10 J g-1higher than those of standard samples. The melting enthalpy obtained from the reversing heat flows was 13-31 J g-1lower in the thermal fractionated samples than in the standard samples. The ratio of the reversing melting enthalpy to the
total melting enthalpy increased with decreasing density of the PE. The melting temperature of the endotherms formed by the
step-wise cooling was 9 K higher than the crystallisation temperature.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | polyethylene reversible melting thermal fractionation TMDSC |
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