Remnant Features in Melt Crystallized Samples of Polyethylenes Originated from Reactor Powders.

A series of reactor powders of ultrahigh molecular weight (UHMW) polyethylenes with different morphology was melted at 160°C for 5 min and cooled in ice water. Low‐frequency Raman spectroscopy was used to characterize the straight‐chain‐segment (SCS) length distribution of both initial and melt‐crystallized materials. A bimodal SCS length distribution was found in the melt‐crystallized sample originated from the reactor powder with a very tenuous amorphous phase. In other samples recrystallized from powders with more ordered structure, the SCS length distribution was unimodal and approximately identical. The result is explained in terms of perfection of lamellar crystals formed under limited time and thermal conditions from differently organized initial structure. [ABSTRACT FROM AUTHOR]