A Study of Mechanical Degradation of Polymer in High Performance GPC

Abstract

Abstract Four narrow distribution polystyrene samples (M = 2.7 × 106, 6 × 106, 6.5 × 106, 7 × 106) were dissolved in tetrahydrofuran and the solutions were passed through a Shodex A-80M column at a concentration of approximately 1 × 10−3 g/ml, injection volume of 500 microliters, and a flow rate of 2 ml/min (i.e., maximun flow rate allowable for this column). Molecular weights of eluants were then determined by viscosity and laser light scattering methods; concentrations were determined by ultra-violet spectrophotometry. From the results of analysis of the eluate, it was shown that no significant degradation was detectable for all four samples in this colulmn which was packed with a cross-linked polystyrene gel. When a silica gel (irregular shaped) column was used, under same operating conditions, only sample PS-4, with a molecular weight of M = 7 × 106 underwent degradation up to 15%. High pressure exerted on the column is believed to be the main cause of the degradation.