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>>The values are calculated from NHC simulations at 10 K.

b>Cubic boundary conditions were used with a box length of 4.6 nm. The values of Cp are from Ref. 30 at 300 K and 400 K.

>>The values are calculated from NHC simulations at 10 K.

b>Cubic boundary conditions were used with a box length of 4.6 nm. The values of Cp are from Ref. 30 at 300 K and 400 K.

Mechanical properties

The compressive modulus, which is quantified by the relation between stress and strain, are investigated for the PE particles by applying an external force in the MD simulations. Figure 7 is a plot of the stress as a function of strain for a PE particle consisting of 12000 beads with a chain length of 100 beads. The slope calculated for the proportional range gives a modulus for compression ofthe polymer nano-particles. It is known that values ofthe tensile modulus ofbulk polyethylene are between 210 and 340 GPa26 In general, the compressive modulus is higher than the tensile modulus2728 In addition, the bulk and tensile strength or yield point are usually much smaller than the modulus for a thermoplastic such as polyethylene. In the MD study ofthe nano-particles, we have observed a compressive modulus that is orders of magnitude smaller than the

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