Characterization of molecular heterogeneities of LLDPE by multiple crystallization-dissolution steps

This article demonstrates that a fractionation technique, based on molecula r segregation during the crystallization from the melt and dissolution of t he crystals, allows a complete characterization of the molecular heterogene ity in the comonomer distribution of linear low density polyethylene. An et hylene-l-hexene copolymer with a bimodal short chain branching distribution has been fractionated by multiple step crystallizations followed by select ive dissolutions in tetrachloroethylene. The relative amount of each compon ent of the distribution in each fraction was determined from the melting cu rves of isothermally crystallized fractions. (C) 2000 Elsevier Science Ltd. All rights reserved.