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Features of High Temperature SEC Column

The GPC UT-800 columns have been developed to prevent shear degradation in the high molecular weight range. The existence of shear degradation can be confirmed using a multi angle light scattering (MALS) detector, which has high sensitivity in the high molecular weight range and can measure absolute molecular weight. In this application, the comparison of results of analysis of high density polyethylene (HDPE) using conventional columns and UT-806M columns is shown. Detection was performed using MALS and RI detectors. With conventional columns, the highest molecular weight portion detected was around 5,000,000. On the other hands, with UT-806M, the highest molecular weight portion was around 20,000,000 and this result shows that high molecular weight portions which cannot be measured using conventional columns exist. In regards to the weight average molecular weight (Mw) obtained from GPC calibration curves, Mw using UT-806M columns is higher than that using conventional columns. From the above results, it can be concluded that shear degradation in the high molecular weight range occurred with conventional columns, but, not with UT-806M columns.

Product name Particle size
(microm)
Mw of HDP
A B
GPC UT-806M 30
1,000,000
468,000
Conventional column
712,000
333,000
(A) Mw(PS) : obtained from calibration curve
(B) Mw(PE) : Mw(PE)=A x 0.468

Sample : 0.3% HDPE-A, High density polyethylene, 500μL

Columns      : Shodex GPC UT-806M (8.0mmI.D. x 300mm) x 2
Eluent       : 0.1% *BHT in ODCB
Flow rate    : 1.0mL/min
Detector     : RI, MALS(Multi angle light scattering)
Column temp. : 145°C

*BHT: Butylhydroxytoluene