ESTABLISHING STRUCTURE-PROPERTY- RELATIONSHIP IN POLYOLEFINS

Abstract

Five commercial samples of polyolefins namely, PP-A, PP-B (both Polypropylene) and LDPE, LLDPE, HDPE have been studied with the aim of developing a deeper understanding of their structure-property relationships. Structural characterization have been carried out at three levels viz., Molecular, Mesoscopic and Macroscopic parameters using a wide range of techniques including Carbon-13 NMR, IR spectroscopy, thermal analysis and High Temperature GPC together with tensile, flexural, impact strength tests, Heat Deflection temperature & Vicat Softening point. Melting temperatures, Melting Enthalpies and Crystallinity values are found to increase with increasing tensile strength and modulus as a direct result of a more regular and close packing of the molecules. Careful examination of the results shows that the presence of co-monomers in the polymer causes the creation of short chain branches and disrupts the regular packing of the molecular chains. Analysis of Carbon-13 NMR data shows that PP...