Quantitative Determination of Plasticizers in Polymeric Mixtures by GPC

Abstract

Organic plasticizers were added to plastics to improve flow and reduce brittleness by lowering the glass transition temperature. The amount of plasticizer added to the base resin determined its efficiency in bringing about these desired changes in properties. Analytical gel permeation chrornatography (GPC) was utilized to quantitatively determine the amount of organic plasticizers in poly(styrene) mixtures. The internal standard method was applied to the determination of triethyleneglycol-dibenzoate and tricyclohexylcitrate over the concentration range of 5.0 to 30.0 wt% in poly(styrene). Linear calibration curves and excellent precision between measurements was demonstrated over the concentration range investigated. GPC analysis has the advantage over spectrophoto-metric techniques in its ability to separate low molecular weight plasticizers: from higher molecular weight resins. In addition to the potential of making quantitative measurements from the detected peak, the associated material can be separated from the polymer, collected, and separately analyzed by UV or IR techniques.