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Z. Dobkowski


A procedure for molecular characteristics of polymers by gel permeation chromatography (GPC)


Polimery 1992, No 4, 146


DOI: dx.doi.org/10.14314/polimery.1992.146

Summary

A modified gel permeation chromatography (GPC) procedure for molecular characteristics of polymers was described. In particular, the following questions were discussed: /1 / selecting reliable values of the Mark-Houwink constans and a) for the universal calibration using the polydispersity exponent apx of the extended Mark-Houwink equation; the experimental values of apx have to be contained within the permissible theoretical limits, i.e. 0.375≤ apn≤1, apv = 0, and -0.125≤apw≤0; / 2 / correcting the calibration curve of the investigated polymer in the range of low M with the use of oligomeric standards; /3 / checking the calibration curve by comparison of the Mv-values obtained from GPC (Mv, GPC) with those of the off-line viscometry (Mv, VISC), thus introducing the viscomctric measurements into the GPC procedure; /4 / taking into account the kinetic energy correction for the viscometric measurements; / 5 / estimating the type of MWD function from the polydispersity degrees (q = Mw/Mn and qz = MZ/MW). A bisphenol-A polycarbonate (Sinvet 220) was characterized as an experimental example. The procedure can be recommended in general for other polymer - GPC-soIvent systems at various temperatures. Thus, reliable molecular characteristics of polymers can be obtained.


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