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Solvent gradient fractionation and chain microstructure of complex branched polyethylene resin


A complex branched polyethylene resin with excellent processing and film-forming properties is fractionated through solvent gradient fractionation (SGF) technique. Here, the good solvent is 1,2,4-trimethylbenzene (TMB) and poor solvent is ethyl cellosolve (ECS). The fractions are further analyzed using high-temperature gel permeation chromatography (GPC) coupled with triple detectors (refractive index (RI)-light scattering (LS)-viscometer (VIS)), and 13C-nuclear magnetic resonance spectroscopy (13C-NMR). The molecular weight distribution of SGF fractions is very narrow, most of them are less than 1.1. The molecular weights of SGF fractions gradually increase as the content of good solvent increases in the mixture. The fractions with different molecular weights all have branching structure, the short chain branching is major in all fractions and along with certain content of long chain branching. Branching distribution across the molecular weight distribution is discussed in detail, and branching distribution within a SGF fraction is also researched.

A complex branched polyethylene resin is fractionated through solvent gradient fractionation (SGF) according to molecular weight. It is elaborated how to select appropriate experimental condition in order to obtain fractions with narrow molecular weight distribution. And the branching distribution in each molecular weight region of the whole resin is clearly understood.

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The authors thank Prof. Tao Tang for his kind supply for the resin. This study was supported by the National Basic Research Program of China (No. 2005CB623806) and National Natural Science Foundation of China (No. 20734006).

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Correspondence to Xiangling Ji.

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Xue, Y., Bo, S. & Ji, X. Solvent gradient fractionation and chain microstructure of complex branched polyethylene resin. J Polym Res 23, 131 (2016).

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  • Solvent gradient fractionation
  • Branch distribution
  • Molecular weight distribution
  • Complex branched polyethylene