A comparative study of ULDPE utilizing DSC and TREF

Abstract

The study of short chain branching (SCB) distribution of crystallizable polymers utilizing temperature rising elution fractionation (TREF) is a well known and established methodology. TREF utilizes the “crystallizability” of polymers in order to fractionate them. Crystallizability is dependent on factors such as short chain branching type, tacticity, and copolymer composition. However, as normally practised, TREF can be both labor and time intensive. Another probe of crystallizability which is generally available is differential scanning calorimetry (DSC). In this work, both solutionand melt-crystallized samples were analyzed by DSC to ascertain the feasibility of utilizing DSC as an alternative or supplementary technique. The DSC results are compared with TREF runs using ultra-low-density polyethylene WLDPE) as the test polymer. Initial work addressing the suitability of using DSC as a complimentary technique to TREF has been reported in the literature [l] for low density polyethylenes. More recently, work has also been reported on linear low density polyethylenes [2,3]. After performing crystallization of DSC samples in a TREF-type microprocessor-controlled oven, a remarkable degree of similarity was observed between TREFand DSC-generated curves.