Separation of polyolefins based on comonomer content using high‐temperature gradient adsorption liquid chromatography with a graphitic carbon column

Abstract

Abstract This report describes the application of a recently developed polyolefin characterization tool based upon gradient adsorption high‐temperature liquid chromatography (HT‐LC) using a graphitic carbon stationary phase to polyolefin homopolymer and previously unreported copolymer systems. Polyolefin‐based materials find utility in a broad range of applications and are differentiated by parameters such as molecular weight and comonomer content. Polymer comonomer distribution is commonly determined by crystallinity‐based separations (ATREF, CRYSTAF). These techniques, however, are time consuming. In addition, some semicrystalline polymers undergo cocrystallization, impacting the techniques' universal utility. Adsorption‐based HT‐LC can ideally overcome the limitations of crystallinity‐based separations, shedding new light on the composition of randomly‐polymerized polyolefins. In this report the basic separation capability of the adsorption HT‐LC technique, using a graphitic carbon column, is demonstrated for poly (ethylene‐ co ‐octene) and poly(ethylene‐ co ‐propylene) systems and compared with select precipitation/redissolution HT‐LC and ATREF results. Select results in this paper are also compared and contrasted to other recent publications on similar separations of polyolefins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011