| 摘要 |
Ziegler-Natta catalyzed linear low density polyethylene which satisfies the following conditions: a) a density, according to ISO 1183, of from 900 to 925 kg/m3, b) a C4-C10-comonomer content, determined by Fourier transform infrared spectroscopy, of 1 to 16 wt % c) a weight average molecular weight Mw, determined by gel permeation chromatography, of at least 200 000, d) wherein the linear low density polyethylene comprises, by Crystallisation Analysis Fractionation (CRYSTAF) an amorphous fraction soluble at a temperature below 30° C. of at most 10 wt % and a fraction crystallising between 60 to 75° C. of at least 35 wt % and e) by temperature rising elution fractionation (TREF) analysis, at least 70 wt % of a crystallising polymer component having an elution temperature range from 60° C. to 94° C. and less than 10 wt % of a crystallising polymer component having an elution temperature range from 30° C. to 60° C. and, f) by Gel Permeation chromatography coupled with Fourier transform infrared spectroscopy detector (GPC-FTIR), a substantially constant short chain branching profile across the molecular weight distribution (MWD) or g) by Gel Permeation chromatography coupled with Fourier transform infrared spectroscopy instruments (GPC-FTIR), a reverse short chain branching profile across the molecular weight distribution (MWD), the linear low density polyethylene being produced in the presence of a special Ziegler-Natta procatalyst and a halogenated aluminium alkyl cocatalyst of the formula (IV) (C1-C4- alkyl)m-Al-X3-m, wherein X is chlorine, bromine, iodine or fluorine and m is 1 or 2.
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