Separation of ethylene‐propylene copolymers and ethylene‐propylene‐diene terpolymers using high‐temperature interactive liquid chromatography

Abstract

Ethylene‐propylene‐diene terpolymers (EPDM) are generally amorphous and, therefore, do not crystallize from solution. Consequently, fractionation techniques based on crystallization, such as crystallization analysis fractionation or temperature rising elution fractionation, cannot be used to analyze their chemical composition distribution. Moreover, no suitable chromatographic system was known, which would enable to separate them according to their chemical composition. In this study, two different sorbent/solvent systems are tested with regard to the capability to separate EPDM‐terpolymers and ethylene‐propylene (EP)‐copolymers according to chemical composition. While porous graphite/1‐decanol system is selective towards ethylene and ethylidene‐2‐norbornene, carbon coated zirconia/2‐ethyl‐1‐hexanol is preferentially selective towards ethylene. Consequently, the earlier system enables to separate both EP copolymers and EPDM according to the chemical composition and the latter mainly according to the ethylene content. The results prove that the chromatographic separation in both sorbent/solvent systems is not influenced by molar mass of a sample or by its long chain branching. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Recent Advances in High-Temperature Fractionation of Polyolefins

“…Experiments confirmed that the molar mass or long chain branching in the above-mentioned samples [166] does not influence the HPLC separation. Independence of the elution volumes on the molar mass >15-20 kg/mol was also found for PE [164] and EP, EB, EO and ethylene/1-decene copolymers [161].…”

“…Macko et al demonstrated the usefulness of the approach for EPC [164] and copolymers of propylene with different tacticities [165]. Moreover, terpolymers of ethylene, propylene and a diene monomer (EPDM) were separated [166]. It was found that both comonomers, ethylene and diene, are adsorbed.…”

Carbonaceous sorbents for high‐temperature interactive liquid chromatography of polyolefins

“…TCB has been used to desorb polyolefins from Hypercarb™ and other carbonaceous sorbents at 140 or 160°C. It is known that temperature can alter the extent of adsorption of synthetic polymers on a solvent/sorbent interface .…”

“…Advantages of the development of the sorbent/solvent systems for selective chromatographic separation of polyolefins were summarized recently by Macko et al . Complete reversible adsorption of polyethylene (PE) and polypropylene (PP) on porous graphite (Hypercarb™) using a solvent gradient consisting of 1‐decanol and 1,2,4‐trichlorobenzene (TCB) at temperatures as high as 160°C was described in series of papers . Various other carbon sorbents have been applied for LC separations of various substances , however, not for polyolefins.…”

Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography

“…4). 1-decanol was chosen as adsorption promoting liquid as the retention of HDPE is larger in comparison with other solvents like 2-octanol and 2-ethyl-1-hexanol and furthermore dissolution was good in 1-decanol [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73]81] and TCB, which is the solvent commonly used in SEC of polyolefins, was applied as desorption promoting liquid. Fig.…”