SEDL / STP / STP1326-EB / STP13822S

Oxidative Induction Time (OIT) Determinations of Polyethylenes: Influences of Temperature, Pressure, and Crucible Materials on the Result

Truttmann, R
Product Management, Mettler-Toledo, Inc., Hightstown, NJ

Schiano, K
Product Management, Mettler-Toledo, Inc., Hightstown, NJ

Riesen, R
Manager, Mettler-Toledo AG, Analytical, Schwerzenbach,

Pages: 9    Published: Jan 1997

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Abstract

The standard procedures for the oxidation induction time (OIT) determinations have been developed to get reproducible and comparable results on the same sample by different users. Experimental conditions such as isothermal measuring temperature, pressure of the surrounding oxygen concentration, and type of crucible material are prescribed to avoid large variations. Many difficulties met in the past may be due to improper selection of the mentioned parameters, namely the temperature accuracy and crucible type and cleanliness. Because of the autocatalytic behavior of the oxidation, the accurate temperature calibration is of tremendous importance, since usual calibration is done dynamically, but the measurements are performed isothermally, that is, without dynamic lag between sample and furnace. Therefore, the shift of the OIT by the variation of temperature, pressure (oxygen concentration), and crucible material is investigated.