Determination of Catalyst Residues in Polyolefins

Description

Polyolefines are the most common plastics. The most widely used technology for preparing polyolefines is the coordination polymerization. Usually metal chlorides or metal oxides are used. The most common catalyst, the so-called Ziegler-Natta-catalysts, consists of titanium chloride in combination with the cocatalyst triethylaluminum. Polyolefines are usually resistant to higher temperature and to many solvents. For trace metal determi nations dissolved samples are necessary and which requires a rigorous sample preparation step. This includes a microwave digestion procedure 1, 2. Many analytical methods are available for the det ermination of trace metals, including atom absorption spectroscopy (AAS), optical emission spe ctroscopy (OES), and inductively coupled-plasma mas s spectrometry (ICP-MS). ICP-MS methods for trace metal determination achieve low detection limits and fast analysis times. In this work typical elements like aluminum, titanium, magnesia, and silicon from a Ziegler-Natta-catalyst system were determined with ICP-MS and AAS, including previous microwave digestion. Different acids and their mixtures e.g. nitric acid, hydrofluoric acid, phosphoric acid, sulfuric acid, and hydrogen peroxide were used for sample dissolution. High pressure (100 bar) closed-vessels were employed for the microwave digestion w hich was performed at temperatures ranging from 180 to 220 °C. It was found that stirring was very important during the microwave digestion. The different analytical methods were compared with each other. The results of the ICP-MS show the lowest detection limits. Detection limits for aluminum, titanium, and magnesia were lower tha n 1 ppb and for silicon not lower than 100 ppb

Period	11 May 2016
Event title	24 th Annual World Forum on Advanced Materials
Event type	Conference
Location	PolandShow on map