A series of copolymers of ethylene with 1-hexene synthesized using a metallocene catalyst are selected and mixed. The blend is fractionated

via

preparative temperature rising elution fractionation (P-TREF). All fractions are characterized via high-temperature gel permeation chromatography (GPC)

13

C nuclear magnetic resonance spectroscopy (

13

C-NMR)

and differential scanning calorimetry (DSC). The changes in the DSC melting peak temperatures of the fractions from P-TREF as a function of elution temperature are almost linear

thereby providing a reference through which the elution temperature of TREF experiments could be selected. Moreover

the standard calibration curve (ethylene/1-hexene) of P-TREF is established

which relates to the degree of short-chain branching of the fractions. The standard calibration curve of P-TREF is beneficial to study on the complicated branching structure of polyethylene. A convenient method for selecting the fractionation temperature for TREF experiments is elaborated. The polyethylene sample is fractionated

via

successive self-nucleation and annealing (SSA) thermal fractionation. A multiple-melting endotherm is obtained through the final DSC heating scan for the sample after SSA thermal fractionation. A series of fractionation temperatures are then selected through the relationship between the DSC melting peak temperature and TREF elution temperature.