Effect of short-chain branching on melt fracture behavior of metallocene and conventional poly(ethylene/α-olefin) copolymers

A phenomenon that can represent a great problem in melt processing is extrudate distortion. This effect can range in intensity from a loss of gloss to gross distortion and is the factor that limits the production rate in certain processes such as the blown film extrusion of linear low‐density polyet...

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Veröffentlicht in:Polymer engineering and science 2012-09, Vol.52 (9), p.1968-1977
Hauptverfasser: Garofalo, E., Incarnato, L., Di Maio, L.
Format: Artikel
Sprache:eng
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Zusammenfassung:A phenomenon that can represent a great problem in melt processing is extrudate distortion. This effect can range in intensity from a loss of gloss to gross distortion and is the factor that limits the production rate in certain processes such as the blown film extrusion of linear low‐density polyethylene (LLDPE). The aim of this work was to investigate the effects that molecular weight distribution and short‐chain branch length have on the observed melt fracture phenomena for poly(ethylene/α‐olefin) resins with similar weight comonomer content and molecular weight. The flow stability analysis conducted in this study has shown that, even increasing of few carbon atoms the short‐chain branch length of the resins, the surface melt fracture phenomena are reduced and/or eliminated. Moreover, the comparison between the metallocene (mLLDPE) and conventional LLDPE samples, with the same comonomer (hexene), showed that the metallocene‐catalyzed resin exhibits early onset and more severe melt fracture, due to its narrower molecular weight distribution. POLYM. ENG. SCI., 52:1968–1977, 2012. © 2012 Society of Plastics Engineers
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.23140