Branched Comonomers in LLDPE—Influence of Short Chain Branch Shape on Crystallinity

Abstract

The crystallinity of Linear Low-Density Polyethylene (LLDPE) is influenced significantly by short-chain branches (SCBs) present in the backbone of the polymer. Despite the importance of this aspect, with only a few linear comonomers being currently used in the commercial production of LLDPE. It is found that by introducing branched comonomers, the melting point and crystallinity of LLDPE can be influenced to a greater extent than with linear comonomers. Since only a few linear comonomers are currently used in the production of LLDPE, the characterization of LLDPEs with branched comonomer has been often overlooked. By combining High-Temperature-Size-Exclusion Chromatography (HT-SEC), Nuclear Magnetic Resonance (NMR) spectroscopy, and Infrared (IR) spectroscopy, it is shown that standard HT-SEC analysis using an IR detector is also applicable to polymers containing branched comonomers.