Correlation of the elution behavior in temperature rising elution fractionation and melting in the solid‐state and in the presence of a diluent of polyethylene copolymers

Abstract

Compositionally homogeneous poly(ethylene-␣-olefin) random copolymers with 1-butene and 1-hexene comonomers have been studied. The melting of solutioncrystallized 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 , the Flory-Huggins interaction parameter, are determined for these copolymers in trichlorobenzene. 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.

Study on molecular chain heterogeneity of linear low‐density polyethylene by cross‐fractionation of temperature rising elution fractionation and successive self‐nucleation/annealing thermal fractionation

“…In particular, the linear relationship can be verified from the plots of crystallinity and melting temperature against elution temperature. These results are in accordance with those of Hosoda and Mirebella 20, 21. In this article, LLDPE is a copolymer of ethylene and 1‐butene, and the content and distribution of SCB are the key factors to its melting temperature and crystallizability.…”

Development of an Integrated On‐Line 2D Analytical TREF‐High Throughput SEC Technique for Polyolefins Characterization

“…After the polymer solution has been loaded onto TREF column H, three‐way valve E switches position from 1‐2 to 1‐3 to bypass the elution solvent from flowing through TREF column H. When the three‐way valve is at position 1‐3 ( Figure ), the eluting solvent goes through route 1‐3‐12 before passing through transfer line T. Being at stationary state, the TREF column undergoes a programmed‐cooling procedure at a given rate, during which polymers in the solution slowly precipitate from the solvent according to their crystallizability, [ 1,43–45 ] coating onto the inert packing material in the TREF column. As is well known, the separation efficiency is strongly determined by the cooling program.…”

Modeling Thermal Properties for Copolymers Covering a Comonomer Composition Range up to 20%

“…That limitation is introduced by defining a minimum in the number of monomers in a crystallizing block, n lim . Such limit is related with the maximum value, n max , according to Equation (8). The value of k is also dependent on cooling conditions and consequently is assumed to be an adjustable parameter.…”

“…However, previous work of Mirabella demonstrated the correlation between results for ethylene/α‐olefin copolymers obtained from DSC and from modern analytical techniques such as CrystaF and TREF . Murphy et al compared the use of FT‐IR and DSC for the study of melting and crystallization of poly(caprolactone) and concluded that DSC technique was the more useful technique for such a determination.…”