STRUCTURE AND MELTING OF BLENDS OF LINEAR AND BRANCHED POLYETHYLENES CRYSTALLIZED AT HIGH UNDERCOOLING

A combined WAXD and d.s.c. study on blends of a series of commercial h igh density and low density (LD) polyethylene (PE) samples rapidly cry stallized from the melt is presented. The melting curves of the materi als are extensively analysed and compared to those exhibited by the in dividual components. The results, besides being indicative of a full c ompatibility of the two components, allow one to distinguish between a blend and an LDPE having both the same average value of branching. Ho wever, other structural parameters such as unit cell volume, macroscop ic density or crystallinity, that are proved to be an exact average of the components, are unable to distinguish between the two materials. The result is applied to a series of commercial bimodal PEs. (C) 1997 Elsevier Science Ltd.