| Abstract: | Compositionally homogeneous poly(ethylene‐α‐olefin) random copolymers with 1‐butene and 1‐hexene comonomers have been studied. The melting of solution‐crystallized specimens of these copolymers in the presence of trichlorobenzene as a diluent with differential scanning calorimetry (DSC) is well correlated with analytical temperature rising elution fractionation (A‐TREF) elution temperature profiles. This indicates that the A‐TREF experiment is essentially a diluent melting experiment. Furthermore, the correction of the corresponding solid‐state melting endotherms of these copolymers with Flory's diluent melting equation yields curves that also correlate very well with the DSC diluent melting curves and the A‐TREF elution temperature profiles. Values of χ, the Flory–Huggins interaction parameter, are determined for these copolymers in trichlorobenzene. χ decreases as short‐chain branching increases. The A‐TREF elution temperature profiles of one of these copolymers are the same, within experimental error, for dilute‐solution crystallizations of the copolymer performed over an extremely broad time schedule (10 s to 3 days). This indicates the profound effect of the branches, as limiting points of the ethylene sequences, in controlling the crystal thickness distribution, which in turn controls the melting point in the presence of the diluent, or the elution temperature from the A‐TREF. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2819–2832, 2001 |
