Effect of molecular structure and topology on network formation in peroxide crosslinked polyethylene

摘要

The present study compared the crosslinking performance of single site linear low density polyethylenes (LLDPE) with high aressure,free radial polymerised,low density polyethylenes (LDPE).The difference in crosslinking performance is not fully explained by different structural porameters such as molar such as molar mass distribution (MMD),M_n,MFR_2 value adn vinyl groups but is related more to the phenomenon of a long chain branched LDPE macromolecule being smaller in size in the molten state than a macromolecule of a liner LLDPE sample of te same molar mass.The result of the difference in size is that the LDPE will contain a larger unmber of intramolecular crosslinking points mentioned are of either a physical or chemical nature.From the perspective of the network build-up,the intermolecular crosslinking points are the most efficient.To compenstae for the larger fraction of intramolecular crosslinking points in LDPE,more peroxide can be added or wvinyl groups cna be introduced.