POLYETHYLENE COMPOSITION HAVING HIGH SWELL RATIO

摘要

The present disclosure relates to a polyethylene composition with improved swell ratio and mechanical properties for use in preparing blow-moulded articles and having the following features:
1) a density from 0.945 to less than 0.952 g/cm3;2) an MIF/MIP ratio from 15 to 30;3) a Shear-Induced Crystallization Index (SIC) from 2.5 to 5.5.

主权项

1. A polyethylene composition comprising:
1) a density from 0.945 to less than 0.952 g/cm3, determined according to ISO 1183 at 23° C.; 2) a ratio MIF/MIP from 15 to 30, wherein the MIF is the melt flow index at 190° C. with a load of 21.60 kg, and the MIP is the melt flow index at 190° C. with a load of 5 kg, both determined according to ISO 1133; and 3) a SIC Index from 2.5 to 5.5;wherein the SIC Index is the Shear-Induced Crystallization Index, determined according to the following relation:
SIC Index=((tonset,SIC@1000×tonset, quiescent)/((HLMI)*100)where tonset,SIC@1000 is measured in seconds and is the time required for crystallization onset under a shear rate of 1000S−1, the tonset, quiescent is measured in seconds and is the crystallization onset time at a temperature of 125° C. under no shear, as determined in isothermal mode by differential scanning calorimetry; and HLMI is the melt flow index determined at 190° C. with a load of 21.6 kg, according to ISO 1133.