high density polyethylene molecular weight

Higher molecular weight results in higher polymer viscosity, although viscosity is also related to the temperature and shear rate used in the test. Characterize the molecular weight of materials using rheological or molecular weight measurements. HDPE grades generally have a molecular weight range of 40,000 to 300,000, and the weight average molecular weight roughly corresponds to the melt index range, that is, from 100 to 0.029g/10min (230°C, 2.16kg). Generally, higher Mw (lower melt index MI) enhances melt strength, better toughness and ESCR, but higher Mw makes processing
The process is more difficult or requires higher pressure or temperature.
Molecular Weight Distribution (MWD): The WD of PE varies from narrow to broad depending on the catalyst used and processing.
The most commonly used MWD measurement index is the unevenness index (HI), which is equal to the weight average molecular weight (Mw) divided by the number average molecular weight (Mn). This index range for all HDPE grades is 4-30. Narrow MWD provides low warpage and high impact during molding. Medium to wide MWD provides processability for most extrusion processes. Broad MWD also improves melt strength and creep resistance.