A 1-octene linear low-density polyethylene (LLDPE) with a bimodal short-chain branching (SCB) distribution has been fractionated with respect to the SCB content using preparative temperature-rising elution fractionation (PTREF). The average SCB content of the fractions obtained ranges from 2.9 to 28.2 branches per 1000 C atoms. Their weight-average molecular weight decreases with increasing degree of branching, while the polydispersity remains rather broad. The fractions exhibit a broad single melting endotherm in contrast to the multiple melting endotherms of the unfractionated copolymer. Dynamic crystallization of the fractions from the melt results in two separate exotherms.
Посилання на статтю:
Molecular, thermal and morphological characterization of narrowly branched fractions of 1-octene linear low-density polyethylene: 1. Molecular and thermal cha racterization / F. Defoor and G. Groeninckx and P. Schouterden and B. Van der Heijden // Polymer. – 1992. – Vol 33. – P. 3878-3883.