Grafting of polyethylenes by reactive extrusion. I. Influence on the molecular structure

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Liste des auteurs: Rosales C, Perera R, Ichazo M, Gonzalez J, Rojas H, Sanchez A, Barrios AD
Editeur: Wiley: 12 months
Année de publication: 1998
Numéro du volume: 70
Numéro de publication: 1
Page d'accueil: 161
Dernière page: 176
Nombre de pages: 16
ISSN: 0021-8995
Languages: Anglais-Royaume-Uni (EN-GB)


Résumé

Grafting of polyethylenes is an important method used in the modification of polyolefins with functional groups. Lately, the use of extruders as polymerization reactors has increased considerably. However, knowledge of the details of the reaction in the extruder is still limited. In this investigation, the grafting of various commercial polyethylenes, high-density polyethylenes (HDPEs), and linear low-density polyethylenes (LLDPEs) with diethyl maleate (DEM) was carried out in two corotating twin-screw extruders with different screw configurations and extrusion conditions. Two initiators at different concentrations were used. It was found that when the initiator level was raised in the LLDPEs the grafting degree increased and the molecular weight distribution of the grafted LLDPE2 did not show appreciable differences when they were compared to the virgin resin. On the other hand, the terminal vinyl group concentrations decreased at the expense of increasing the trans unsaturation concentrations. This last result is consistent with the formation of long-chain branching. Additionally, the weight-average molecular weight of grafted high-density polyethylene (HDPE1-g-DEM) decreased. The grafting efficiencies were consistent with the attained residence times and also with the kinetics of the decomposition of the peroxides. (C) 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 161-176, 1998.


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